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Genesis-Plus-GX/core/vdp_ctrl.c

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/***************************************************************************************
* Genesis Plus
* Video Display Processor (68k & Z80 CPU interface)
*
* Support for SG-1000 (TMS99xx & 315-5066), Master System (315-5124 & 315-5246), Game Gear & Mega Drive VDP
*
* Copyright (C) 1998-2003 Charles Mac Donald (original code)
* Copyright (C) 2007-2017 Eke-Eke (Genesis Plus GX)
*
* Redistribution and use of this code or any derivative works are permitted
* provided that the following conditions are met:
*
* - Redistributions may not be sold, nor may they be used in a commercial
* product or activity.
*
* - Redistributions that are modified from the original source must include the
* complete source code, including the source code for all components used by a
* binary built from the modified sources. However, as a special exception, the
* source code distributed need not include anything that is normally distributed
* (in either source or binary form) with the major components (compiler, kernel,
* and so on) of the operating system on which the executable runs, unless that
* component itself accompanies the executable.
*
* - Redistributions must reproduce the above copyright notice, this list of
* conditions and the following disclaimer in the documentation and/or other
* materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************************/
#include "shared.h"
#include "hvc.h"
/* Mark a pattern as modified */
#define MARK_BG_DIRTY(addr) \
{ \
name = (addr >> 5) & 0x7FF; \
if (bg_name_dirty[name] == 0) \
{ \
bg_name_list[bg_list_index++] = name; \
} \
bg_name_dirty[name] |= (1 << ((addr >> 2) & 7)); \
}
/* VDP context */
uint8 ALIGNED_(4) sat[0x400]; /* Internal copy of sprite attribute table */
uint8 ALIGNED_(4) vram[0x10000]; /* Video RAM (64K x 8-bit) */
uint8 ALIGNED_(4) cram[0x80]; /* On-chip color RAM (64 x 9-bit) */
uint8 ALIGNED_(4) vsram[0x80]; /* On-chip vertical scroll RAM (40 x 11-bit) */
uint8 reg[0x20]; /* Internal VDP registers (23 x 8-bit) */
uint8 hint_pending; /* 0= Line interrupt is pending */
uint8 vint_pending; /* 1= Frame interrupt is pending */
uint16 status; /* VDP status flags */
uint32 dma_length; /* DMA remaining length */
/* Global variables */
uint16 ntab; /* Name table A base address */
uint16 ntbb; /* Name table B base address */
uint16 ntwb; /* Name table W base address */
uint16 satb; /* Sprite attribute table base address */
uint16 hscb; /* Horizontal scroll table base address */
uint8 bg_name_dirty[0x800]; /* 1= This pattern is dirty */
uint16 bg_name_list[0x800]; /* List of modified pattern indices */
uint16 bg_list_index; /* # of modified patterns in list */
uint8 hscroll_mask; /* Horizontal Scrolling line mask */
uint8 playfield_shift; /* Width of planes A, B (in bits) */
uint8 playfield_col_mask; /* Playfield column mask */
uint16 playfield_row_mask; /* Playfield row mask */
uint16 vscroll; /* Latched vertical scroll value */
uint8 odd_frame; /* 1: odd field, 0: even field */
uint8 im2_flag; /* 1= Interlace mode 2 is being used */
uint8 interlaced; /* 1: Interlaced mode 1 or 2 */
uint8 vdp_pal; /* 1: PAL , 0: NTSC (default) */
uint8 h_counter; /* Horizontal counter */
uint16 v_counter; /* Vertical counter */
uint16 vc_max; /* Vertical counter overflow value */
uint16 lines_per_frame; /* PAL: 313 lines, NTSC: 262 lines */
uint16 max_sprite_pixels; /* Max. sprites pixels per line (parsing & rendering) */
int32 fifo_write_cnt; /* VDP FIFO write count */
uint32 fifo_slots; /* VDP FIFO access slot count */
uint32 hvc_latch; /* latched HV counter */
const uint8 *hctab; /* pointer to H Counter table */
/* Function pointers */
void (*vdp_68k_data_w)(unsigned int data);
void (*vdp_z80_data_w)(unsigned int data);
unsigned int (*vdp_68k_data_r)(void);
unsigned int (*vdp_z80_data_r)(void);
/* Function prototypes */
static void vdp_68k_data_w_m4(unsigned int data);
static void vdp_68k_data_w_m5(unsigned int data);
static unsigned int vdp_68k_data_r_m4(void);
static unsigned int vdp_68k_data_r_m5(void);
static void vdp_z80_data_w_m4(unsigned int data);
static void vdp_z80_data_w_m5(unsigned int data);
static unsigned int vdp_z80_data_r_m4(void);
static unsigned int vdp_z80_data_r_m5(void);
static void vdp_z80_data_w_ms(unsigned int data);
static void vdp_z80_data_w_gg(unsigned int data);
static void vdp_z80_data_w_sg(unsigned int data);
static void vdp_bus_w(unsigned int data);
static void vdp_fifo_update(unsigned int cycles);
static void vdp_reg_w(unsigned int r, unsigned int d, unsigned int cycles);
static void vdp_dma_68k_ext(unsigned int length);
static void vdp_dma_68k_ram(unsigned int length);
static void vdp_dma_68k_io(unsigned int length);
static void vdp_dma_copy(unsigned int length);
static void vdp_dma_fill(unsigned int length);
/* Tables that define the playfield layout */
static const uint8 hscroll_mask_table[] = { 0x00, 0x07, 0xF8, 0xFF };
static const uint8 shift_table[] = { 6, 7, 0, 8 };
static const uint8 col_mask_table[] = { 0x0F, 0x1F, 0x0F, 0x3F };
static const uint16 row_mask_table[] = { 0x0FF, 0x1FF, 0x2FF, 0x3FF };
static uint8 border; /* Border color index */
static uint8 pending; /* Pending write flag */
static uint8 code; /* Code register */
static uint8 dma_type; /* DMA mode */
static uint16 addr; /* Address register */
static uint16 addr_latch; /* Latched A15, A14 of address */
static uint16 sat_base_mask; /* Base bits of SAT */
static uint16 sat_addr_mask; /* Index bits of SAT */
static uint16 dma_src; /* DMA source address */
static uint32 dma_endCycles; /* 68k cycles to DMA end */
static int dmafill; /* DMA Fill pending flag */
static int cached_write; /* 2nd part of 32-bit CTRL port write (Genesis mode) or LSB of CRAM data (Game Gear mode) */
static uint16 fifo[4]; /* FIFO ring-buffer */
static int fifo_idx; /* FIFO write index */
static int fifo_byte_access; /* FIFO byte access flag */
static uint32 fifo_cycles; /* FIFO next access cycle */
/* set Z80 or 68k interrupt lines */
static void (*set_irq_line)(unsigned int level);
static void (*set_irq_line_delay)(unsigned int level);
/* Vertical counter overflow values (see hvc.h) */
static const uint16 vc_table[4][2] =
{
/* NTSC, PAL */
{0xDA , 0xF2}, /* Mode 4 (192 lines) */
{0xEA , 0x102}, /* Mode 5 (224 lines) */
{0xDA , 0xF2}, /* Mode 4 (192 lines) */
{0x106, 0x10A} /* Mode 5 (240 lines) */
};
/* DMA Timings (number of access slots per line) */
static const uint8 dma_timing[2][2] =
{
/* H32, H40 */
{16 , 18}, /* active display */
{166, 204} /* blank display */
};
/* DMA processing functions (set by VDP register 23 high nibble) */
static void (*const dma_func[16])(unsigned int length) =
{
/* 0x0-0x3 : DMA from 68k bus $000000-$7FFFFF (external area) */
vdp_dma_68k_ext,vdp_dma_68k_ext,vdp_dma_68k_ext,vdp_dma_68k_ext,
/* 0x4-0x7 : DMA from 68k bus $800000-$FFFFFF (internal RAM & I/O) */
vdp_dma_68k_ram, vdp_dma_68k_io,vdp_dma_68k_ram,vdp_dma_68k_ram,
/* 0x8-0xB : DMA Fill */
vdp_dma_fill,vdp_dma_fill,vdp_dma_fill,vdp_dma_fill,
/* 0xC-0xF : DMA Copy */
vdp_dma_copy,vdp_dma_copy,vdp_dma_copy,vdp_dma_copy
};
/* BG rendering functions */
static void (*const render_bg_modes[16])(int line) =
{
render_bg_m0, /* Graphics I */
render_bg_m2, /* Graphics II */
render_bg_m4, /* Mode 4 */
render_bg_m4, /* Mode 4 */
render_bg_m3, /* Multicolor */
render_bg_m3x, /* Multicolor (Extended PG) */
render_bg_m4, /* Mode 4 */
render_bg_m4, /* Mode 4 */
render_bg_m1, /* Text */
render_bg_m1x, /* Text (Extended PG) */
render_bg_m4, /* Mode 4 */
render_bg_m4, /* Mode 4 */
render_bg_inv, /* Invalid (1+3) */
render_bg_inv, /* Invalid (1+2+3) */
render_bg_m4, /* Mode 4 */
render_bg_m4, /* Mode 4 */
};
/*--------------------------------------------------------------------------*/
/* Init, reset, context functions */
/*--------------------------------------------------------------------------*/
void vdp_init(void)
{
/* PAL/NTSC timings */
lines_per_frame = vdp_pal ? 313: 262;
/* CPU interrupt line(s)*/
if ((system_hw & SYSTEM_PBC) == SYSTEM_MD)
{
/* 68k cpu */
set_irq_line = m68k_set_irq;
set_irq_line_delay = m68k_set_irq_delay;
}
else
{
/* Z80 cpu */
set_irq_line = z80_set_irq_line;
set_irq_line_delay = z80_set_irq_line;
}
}
void vdp_reset(void)
{
int i;
memset ((char *) sat, 0, sizeof (sat));
memset ((char *) vram, 0, sizeof (vram));
memset ((char *) cram, 0, sizeof (cram));
memset ((char *) vsram, 0, sizeof (vsram));
memset ((char *) reg, 0, sizeof (reg));
addr = 0;
addr_latch = 0;
code = 0;
pending = 0;
border = 0;
hint_pending = 0;
vint_pending = 0;
dmafill = 0;
dma_src = 0;
dma_type = 0;
dma_length = 0;
dma_endCycles = 0;
odd_frame = 0;
im2_flag = 0;
interlaced = 0;
fifo_write_cnt = 0;
fifo_cycles = 0;
fifo_slots = 0;
fifo_idx = 0;
cached_write = -1;
fifo_byte_access = 1;
ntab = 0;
ntbb = 0;
ntwb = 0;
satb = 0;
hscb = 0;
vscroll = 0;
hscroll_mask = 0x00;
playfield_shift = 6;
playfield_col_mask = 0x0F;
playfield_row_mask = 0x0FF;
sat_base_mask = 0xFE00;
sat_addr_mask = 0x01FF;
/* reset pattern cache changes */
bg_list_index = 0;
memset ((char *) bg_name_dirty, 0, sizeof (bg_name_dirty));
memset ((char *) bg_name_list, 0, sizeof (bg_name_list));
/* default Window clipping */
window_clip(0,0);
/* reset VDP status (FIFO empty flag is set) */
if (system_hw & SYSTEM_MD)
{
status = vdp_pal | 0x200;
}
else
{
status = 0;
}
/* default display area */
bitmap.viewport.w = 256;
bitmap.viewport.h = 192;
bitmap.viewport.ow = 256;
bitmap.viewport.oh = 192;
/* default HVC */
hvc_latch = 0x10000;
hctab = cycle2hc32;
vc_max = vc_table[0][vdp_pal];
v_counter = bitmap.viewport.h;
h_counter = 0xff;
/* default sprite pixel width */
max_sprite_pixels = 256;
/* default overscan area */
if ((system_hw == SYSTEM_GG) && !config.gg_extra)
{
/* Display area reduced to 160x144 if overscan is disabled */
bitmap.viewport.x = (config.overscan & 2) ? 14 : -48;
bitmap.viewport.y = (config.overscan & 1) ? (24 * (vdp_pal + 1)) : -24;
}
else
{
bitmap.viewport.x = (config.overscan & 2) * 7;
bitmap.viewport.y = (config.overscan & 1) * 24 * (vdp_pal + 1);
}
/* default rendering mode */
update_bg_pattern_cache = update_bg_pattern_cache_m4;
if (system_hw < SYSTEM_MD)
{
/* Mode 0 */
render_bg = render_bg_m0;
render_obj = render_obj_tms;
parse_satb = parse_satb_tms;
}
else
{
/* Mode 4 */
render_bg = render_bg_m4;
render_obj = render_obj_m4;
parse_satb = parse_satb_m4;
}
/* default 68k bus interface (Mega Drive VDP only) */
vdp_68k_data_w = vdp_68k_data_w_m4;
vdp_68k_data_r = vdp_68k_data_r_m4;
/* default Z80 bus interface */
switch (system_hw)
{
case SYSTEM_SG:
case SYSTEM_SGII:
{
/* SG-1000 (TMS99xx) or SG-1000 II (315-5066) VDP */
vdp_z80_data_w = vdp_z80_data_w_sg;
vdp_z80_data_r = vdp_z80_data_r_m4;
break;
}
case SYSTEM_GG:
{
/* Game Gear VDP */
vdp_z80_data_w = vdp_z80_data_w_gg;
vdp_z80_data_r = vdp_z80_data_r_m4;
break;
}
case SYSTEM_MARKIII:
case SYSTEM_SMS:
case SYSTEM_SMS2:
case SYSTEM_GGMS:
{
/* Master System or Game Gear (in MS compatibility mode) VDP */
vdp_z80_data_w = vdp_z80_data_w_ms;
vdp_z80_data_r = vdp_z80_data_r_m4;
break;
}
default:
{
/* Mega Drive VDP (in MS compatibility mode) */
vdp_z80_data_w = vdp_z80_data_w_m4;
vdp_z80_data_r = vdp_z80_data_r_m4;
break;
}
}
/* H-INT is disabled on startup (verified on VA4 MD1 with 315-5313 VDP) */
reg[10] = 0xFF;
/* Master System specific */
if ((system_hw & SYSTEM_SMS) && (!(config.bios & 1) || !(system_bios & SYSTEM_SMS)))
{
/* force registers initialization (normally done by BOOT ROM on all Master System models) */
vdp_reg_w(0 , 0x36, 0);
vdp_reg_w(1 , 0x80, 0);
vdp_reg_w(2 , 0xFF, 0);
vdp_reg_w(3 , 0xFF, 0);
vdp_reg_w(4 , 0xFF, 0);
vdp_reg_w(5 , 0xFF, 0);
vdp_reg_w(6 , 0xFF, 0);
/* Mode 4 */
render_bg = render_bg_m4;
render_obj = render_obj_m4;
parse_satb = parse_satb_m4;
}
/* Mega Drive specific */
else if (((system_hw == SYSTEM_MD) || (system_hw == SYSTEM_MCD)) && (config.bios & 1) && !(system_bios & SYSTEM_MD))
{
/* force registers initialization (normally done by BOOT ROM, only on Mega Drive model with TMSS) */
vdp_reg_w(0 , 0x04, 0);
vdp_reg_w(1 , 0x04, 0);
vdp_reg_w(12, 0x81, 0);
vdp_reg_w(15, 0x02, 0);
}
/* reset color palette */
for(i = 0; i < 0x20; i ++)
{
color_update_m4(i, 0x00);
}
color_update_m4(0x40, 0x00);
}
int vdp_context_save(uint8 *state)
{
int bufferptr = 0;
save_param(sat, sizeof(sat));
save_param(vram, sizeof(vram));
save_param(cram, sizeof(cram));
save_param(vsram, sizeof(vsram));
save_param(reg, sizeof(reg));
save_param(&addr, sizeof(addr));
save_param(&addr_latch, sizeof(addr_latch));
save_param(&code, sizeof(code));
save_param(&pending, sizeof(pending));
save_param(&status, sizeof(status));
save_param(&dmafill, sizeof(dmafill));
save_param(&fifo_idx, sizeof(fifo_idx));
save_param(&fifo, sizeof(fifo));
save_param(&h_counter, sizeof(h_counter));
save_param(&hint_pending, sizeof(hint_pending));
save_param(&vint_pending, sizeof(vint_pending));
save_param(&dma_length, sizeof(dma_length));
save_param(&dma_type, sizeof(dma_type));
save_param(&dma_src, sizeof(dma_src));
save_param(&cached_write, sizeof(cached_write));
return bufferptr;
}
int vdp_context_load(uint8 *state)
{
int i, bufferptr = 0;
uint8 temp_reg[0x20];
load_param(sat, sizeof(sat));
load_param(vram, sizeof(vram));
load_param(cram, sizeof(cram));
load_param(vsram, sizeof(vsram));
load_param(temp_reg, sizeof(temp_reg));
/* restore VDP registers */
if (system_hw < SYSTEM_MD)
{
if (system_hw >= SYSTEM_MARKIII)
{
for (i=0;i<0x10;i++)
{
pending = 1;
addr_latch = temp_reg[i];
vdp_sms_ctrl_w(0x80 | i);
}
}
else
{
/* TMS-99xx registers are updated directly to prevent spurious 4K->16K VRAM switching */
for (i=0;i<0x08;i++)
{
reg[i] = temp_reg[i];
}
/* Rendering mode */
render_bg = render_bg_modes[((reg[0] & 0x02) | (reg[1] & 0x18)) >> 1];
}
}
else
{
for (i=0;i<0x20;i++)
{
vdp_reg_w(i, temp_reg[i], 0);
}
}
load_param(&addr, sizeof(addr));
load_param(&addr_latch, sizeof(addr_latch));
load_param(&code, sizeof(code));
load_param(&pending, sizeof(pending));
load_param(&status, sizeof(status));
load_param(&dmafill, sizeof(dmafill));
load_param(&fifo_idx, sizeof(fifo_idx));
load_param(&fifo, sizeof(fifo));
load_param(&h_counter, sizeof(h_counter));
load_param(&hint_pending, sizeof(hint_pending));
load_param(&vint_pending, sizeof(vint_pending));
load_param(&dma_length, sizeof(dma_length));
load_param(&dma_type, sizeof(dma_type));
load_param(&dma_src, sizeof(dma_src));
load_param(&cached_write, sizeof(cached_write));
/* restore FIFO byte access flag */
fifo_byte_access = ((code & 0x0F) < 0x03);
/* restore current NTSC/PAL mode */
if (system_hw & SYSTEM_MD)
{
status = (status & ~1) | vdp_pal;
}
if (reg[1] & 0x04)
{
/* Mode 5 */
bg_list_index = 0x800;
/* reinitialize palette */
color_update_m5(0, *(uint16 *)&cram[border << 1]);
for(i = 1; i < 0x40; i++)
{
color_update_m5(i, *(uint16 *)&cram[i << 1]);
}
}
else
{
/* Modes 0,1,2,3,4 */
bg_list_index = 0x200;
/* reinitialize palette */
for(i = 0; i < 0x20; i ++)
{
color_update_m4(i, *(uint16 *)&cram[i << 1]);
}
color_update_m4(0x40, *(uint16 *)&cram[(0x10 | (border & 0x0F)) << 1]);
}
/* invalidate tile cache */
for (i=0;i<bg_list_index;i++)
{
bg_name_list[i]=i;
bg_name_dirty[i]=0xFF;
}
return bufferptr;
}
/*--------------------------------------------------------------------------*/
/* DMA update function (Mega Drive VDP only) */
/*--------------------------------------------------------------------------*/
void vdp_dma_update(unsigned int cycles)
{
unsigned int dma_cycles, dma_bytes;
/* DMA transfer rate (bytes per line)
DMA Mode Width Display Transfer Count
-----------------------------------------------------
68K > VDP 32-cell Active 16
Blanking 166
40-cell Active 18
Blanking 204
VRAM Fill 32-cell Active 15
Blanking 165
40-cell Active 17
Blanking 203
VRAM Copy 32-cell Active 8
Blanking 83
40-cell Active 9
Blanking 102
'Active' is the active display period, 'Blanking' is either the vertical
blanking period or when the display is forcibly blanked via register #1.
The above transfer counts are all in bytes, unless the destination is
CRAM or VSRAM for a 68K > VDP transfer, in which case it is in words.
*/
unsigned int rate = dma_timing[(status & 8) || !(reg[1] & 0x40)][reg[12] & 1];
/* Adjust for 68k bus DMA to VRAM (one word = 2 access) or DMA Copy (one read + one write = 2 access) */
rate = rate >> (dma_type & 1);
/* Remaining DMA cycles */
if (status & 8)
{
/* Process DMA until the end of VBLANK */
/* NOTE: DMA timings can not change during VBLANK because active display width cannot be modified. */
/* Indeed, writing VDP registers during DMA is either impossible (when doing DMA from 68k bus, CPU */
/* is locked) or will abort DMA operation (in case of DMA Fill or Copy). */
dma_cycles = ((lines_per_frame - bitmap.viewport.h - 1) * MCYCLES_PER_LINE) - cycles;
}
else
{
/* Process DMA until the end of current line */
dma_cycles = (mcycles_vdp + MCYCLES_PER_LINE) - cycles;
}
/* Remaining DMA bytes for that line */
dma_bytes = (dma_cycles * rate) / MCYCLES_PER_LINE;
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] DMA type %d (%d access/line)(%d cycles left)-> %d access (%d remaining) (%x)\n", v_counter, (v_counter + (cycles - mcycles_vdp)/MCYCLES_PER_LINE)%lines_per_frame, cycles, cycles%MCYCLES_PER_LINE,dma_type, rate, dma_cycles, dma_bytes, dma_length, m68k_get_reg(M68K_REG_PC));
#endif
/* Check if DMA can be finished before the end of current line */
if (dma_length < dma_bytes)
{
/* Adjust remaining DMA bytes */
dma_bytes = dma_length;
dma_cycles = (dma_bytes * MCYCLES_PER_LINE) / rate;
}
/* Update DMA timings */
if (dma_type < 2)
{
/* 68K is frozen during DMA from 68k bus */
m68k.cycles = cycles + dma_cycles;
#ifdef LOGVDP
error("-->CPU frozen for %d cycles\n", dma_cycles);
#endif
}
else
{
/* Set DMA Busy flag */
status |= 0x02;
/* 68K is still running, set DMA end cycle */
dma_endCycles = cycles + dma_cycles;
#ifdef LOGVDP
error("-->DMA ends in %d cycles\n", dma_cycles);
#endif
}
/* Process DMA */
if (dma_bytes)
{
/* Update DMA length */
dma_length -= dma_bytes;
/* Process DMA operation */
dma_func[reg[23] >> 4](dma_bytes);
/* Check if DMA is finished */
if (!dma_length)
{
/* DMA source address registers are incremented during DMA (even DMA Fill) */
uint16 end = reg[21] + (reg[22] << 8) + reg[19] + (reg[20] << 8);
reg[21] = end & 0xff;
reg[22] = end >> 8;
/* DMA length registers are decremented during DMA */
reg[19] = reg[20] = 0;
/* perform cached write, if any */
if (cached_write >= 0)
{
vdp_68k_ctrl_w(cached_write);
cached_write = -1;
}
}
}
}
/*--------------------------------------------------------------------------*/
/* Control port access functions */
/*--------------------------------------------------------------------------*/
void vdp_68k_ctrl_w(unsigned int data)
{
/* Check pending flag */
if (pending == 0)
{
/* A single long word write instruction could have started DMA with the first word */
if (dma_length)
{
/* 68k is frozen during 68k bus DMA */
/* Second word should be written after DMA completion */
/* See Formula One & Kawasaki Superbike Challenge */
if (dma_type < 2)
{
/* Latch second control word for later */
cached_write = data;
return;
}
}
/* Check CD0-CD1 bits */
if ((data & 0xC000) == 0x8000)
{
/* VDP register write */
vdp_reg_w((data >> 8) & 0x1F, data & 0xFF, m68k.cycles);
}
else
{
/* Set pending flag (Mode 5 only) */
pending = reg[1] & 4;
}
/* Update address and code registers */
addr = addr_latch | (data & 0x3FFF);
code = ((code & 0x3C) | ((data >> 14) & 0x03));
}
else
{
/* Clear pending flag */
pending = 0;
/* Save address bits A15 and A14 */
addr_latch = (data & 3) << 14;
/* Update address and code registers */
addr = addr_latch | (addr & 0x3FFF);
code = ((code & 0x03) | ((data >> 2) & 0x3C));
/* Detect DMA operation (CD5 bit set) */
if (code & 0x20)
{
/* DMA must be enabled */
if (reg[1] & 0x10)
{
/* DMA type */
switch (reg[23] >> 6)
{
case 2:
{
/* DMA Fill */
dma_type = 2;
/* DMA is pending until next DATA port write */
dmafill = 1;
/* Set DMA Busy flag */
status |= 0x02;
/* DMA end cycle is not initialized yet (this prevents DMA Busy flag from being cleared on VDP status read) */
dma_endCycles = 0xffffffff;
break;
}
case 3:
{
/* DMA Copy */
dma_type = 3;
/* DMA length */
dma_length = (reg[20] << 8) | reg[19];
/* Zero DMA length (pre-decrementing counter) */
if (!dma_length)
{
dma_length = 0x10000;
}
/* DMA source address */
dma_src = (reg[22] << 8) | reg[21];
/* Trigger DMA */
vdp_dma_update(m68k.cycles);
break;
}
default:
{
/* DMA from 68k bus */
dma_type = (code & 0x06) ? 0 : 1;
/* DMA length */
dma_length = (reg[20] << 8) | reg[19];
/* Zero DMA length (pre-decrementing counter) */
if (!dma_length)
{
dma_length = 0x10000;
}
/* DMA source address */
dma_src = (reg[22] << 8) | reg[21];
/* Transfer from SVP ROM/RAM ($000000-$3fffff) or CD Word-RAM ($200000-$3fffff/$600000-$7fffff) */
if (((system_hw == SYSTEM_MCD) && ((reg[23] & 0x70) == ((scd.cartridge.boot >> 1) + 0x10))) || (svp && !(reg[23] & 0x60)))
{
/* source data is available with one cycle delay, i.e first word written by VDP is */
/* previous data being held on 68k bus at that time, then source words are written */
/* normally to VDP RAM, with only last source word being ignored */
addr += reg[15];
dma_length--;
}
/* Trigger DMA */
vdp_dma_update(m68k.cycles);
break;
}
}
}
}
}
/*
FIFO emulation (Chaos Engine/Soldier of Fortune, Double Clutch, Sol Deace)
--------------------------------------------------------------------------
Each VRAM access is byte wide, so one VRAM write (word) need two slot access.
NOTE: Invalid code 0x02 (register write) should not behave the same as VRAM
access, i.e data is ignored and only one access slot is used for each word,
BUT a few games ("Clue", "Microcosm") which accidentally corrupt code value
will have issues when emulating FIFO timings. They likely work fine on real
hardware because of periodical 68k wait-states which have been observed and
would naturaly add some delay between writes. Until those wait-states are
accurately measured and emulated, delay is forced when invalid code value
is being used.
*/
fifo_byte_access = ((code & 0x0F) <= 0x02);
}
/* Mega Drive VDP control port specific (MS compatibility mode) */
void vdp_z80_ctrl_w(unsigned int data)
{
switch (pending)
{
case 0:
{
/* Latch LSB */
addr_latch = data;
/* Set LSB pending flag */
pending = 1;
return;
}
case 1:
{
/* Update address and code registers */
addr = (addr & 0xC000) | ((data & 0x3F) << 8) | addr_latch ;
code = ((code & 0x3C) | ((data >> 6) & 0x03));
if ((code & 0x03) == 0x02)
{
/* VDP register write */
vdp_reg_w(data & 0x1F, addr_latch, Z80.cycles);
/* Clear pending flag */
pending = 0;
return;
}
/* Set Mode 5 pending flag */
pending = (reg[1] & 4) >> 1;
if (!pending && !(code & 0x03))
{
/* Process VRAM read */
fifo[0] = vram[addr & 0x3FFF];
/* Increment address register */
addr += (reg[15] + 1);
}
return;
}
case 2:
{
/* Latch LSB */
addr_latch = data;
/* Set LSB pending flag */
pending = 3;
return;
}
case 3:
{
/* Clear pending flag */
pending = 0;
/* Update address and code registers */
addr = ((addr_latch & 3) << 14) | (addr & 0x3FFF);
code = ((code & 0x03) | ((addr_latch >> 2) & 0x3C));
/* Detect DMA operation (CD5 bit set) */
if (code & 0x20)
{
/* DMA should be enabled */
if (reg[1] & 0x10)
{
/* DMA type */
switch (reg[23] >> 6)
{
case 2:
{
/* DMA Fill */
dma_type = 2;
/* DMA is pending until next DATA port write */
dmafill = 1;
/* Set DMA Busy flag */
status |= 0x02;
/* DMA end cycle is not initialized yet (this prevents DMA Busy flag from being cleared on VDP status read) */
dma_endCycles = 0xffffffff;
break;
}
case 3:
{
/* DMA copy */
dma_type = 3;
/* DMA length */
dma_length = (reg[20] << 8) | reg[19];
/* Zero DMA length (pre-decrementing counter) */
if (!dma_length)
{
dma_length = 0x10000;
}
/* DMA source address */
dma_src = (reg[22] << 8) | reg[21];
/* Trigger DMA */
vdp_dma_update(Z80.cycles);
break;
}
default:
{
/* DMA from 68k bus does not work when Z80 is in control */
break;
}
}
}
}
}
return;
}
}
/* Master System & Game Gear VDP control port specific */
void vdp_sms_ctrl_w(unsigned int data)
{
if (pending == 0)
{
/* Update address register LSB */
addr = (addr & 0x3F00) | (data & 0xFF);
/* Latch LSB */
addr_latch = data;
/* Set LSB pending flag */
pending = 1;
}
else
{
/* Update address and code registers */
code = (data >> 6) & 3;
addr = (data << 8 | addr_latch) & 0x3FFF;
/* Clear pending flag */
pending = 0;
if (code == 0)
{
/* Process VRAM read */
fifo[0] = vram[addr & 0x3FFF];
/* Increment address register */
addr = (addr + 1) & 0x3FFF;
return;
}
if (code == 2)
{
/* Save current VDP mode */
int mode, prev = (reg[0] & 0x06) | (reg[1] & 0x18);
/* Write VDP register 0-15 */
vdp_reg_w(data & 0x0F, addr_latch, Z80.cycles);
/* Check VDP mode changes */
mode = (reg[0] & 0x06) | (reg[1] & 0x18);
prev ^= mode;
if (prev)
{
/* Check for extended modes */
if (system_hw > SYSTEM_SMS)
{
int height;
if (mode == 0x0E) /* M1=0,M2=1,M3=1,M4=1 */
{
/* Mode 4 extended (240 lines) */
height = 240;
/* Update vertical counter max value */
vc_max = vc_table[3][vdp_pal];
}
else if (mode == 0x16) /* M1=1,M2=1,M3=0,M4=1 */
{
/* Mode 4 extended (224 lines) */
height = 224;
/* Update vertical counter max value */
vc_max = vc_table[1][vdp_pal];
}
else
{
/* Mode 4 default (224 lines) */
height = 192;
/* Default vertical counter max value */
vc_max = vc_table[0][vdp_pal];
}
/* viewport changes should be applied on next frame */
if (height != bitmap.viewport.h)
{
bitmap.viewport.changed |= 2;
}
}
/* Rendering mode */
render_bg = render_bg_modes[mode>>1];
/* Mode switching */
if (prev & 0x04)
{
int i;
if (mode & 0x04)
{
/* Mode 4 sprites */
parse_satb = parse_satb_m4;
render_obj = render_obj_m4;
/* force BG cache update*/
bg_list_index = 0x200;
}
else
{
/* TMS-mode sprites */
parse_satb = parse_satb_tms;
render_obj = render_obj_tms;
/* BG cache is not used */
bg_list_index = 0;
}
/* reinitialize palette */
for(i = 0; i < 0x20; i ++)
{
color_update_m4(i, *(uint16 *)&cram[i << 1]);
}
color_update_m4(0x40, *(uint16 *)&cram[(0x10 | (border & 0x0F)) << 1]);
}
}
}
}
}
/* SG-1000 VDP (TMS99xx) control port specific */
void vdp_tms_ctrl_w(unsigned int data)
{
if (pending == 0)
{
/* Latch LSB */
addr_latch = data;
/* Set LSB pending flag */
pending = 1;
}
else
{
/* Update address and code registers */
code = (data >> 6) & 3;
addr = (data << 8 | addr_latch) & 0x3FFF;
/* Clear pending flag */
pending = 0;
if (code == 0)
{
/* Process VRAM read */
fifo[0] = vram[addr & 0x3FFF];
/* Increment address register */
addr = (addr + 1) & 0x3FFF;
return;
}
if (code & 2)
{
/* VDP register index (0-7) */
data &= 0x07;
/* Write VDP register */
vdp_reg_w(data, addr_latch, Z80.cycles);
/* Check VDP mode changes */
if (data < 2)
{
/* Rendering mode */
render_bg = render_bg_modes[((reg[0] & 0x02) | (reg[1] & 0x18)) >> 1];
}
}
}
}
/*
* Status register
*
* Bits
* 0 NTSC(0)/PAL(1)
* 1 DMA Busy
* 2 During HBlank
* 3 During VBlank
* 4 0:1 even:odd field (interlaced modes only)
* 5 Sprite collision
* 6 Too many sprites per line
* 7 v interrupt occurred
* 8 Write FIFO full
* 9 Write FIFO empty
* 10 - 15 Open Bus
*/
unsigned int vdp_68k_ctrl_r(unsigned int cycles)
{
unsigned int temp;
/* Cycle-accurate VDP status read (68k read cycle takes four CPU cycles i.e 28 Mcycles) */
cycles += 4 * 7;
/* Update FIFO status flags if not empty */
if (fifo_write_cnt)
{
vdp_fifo_update(cycles);
}
/* Check if DMA Busy flag is set */
if (status & 2)
{
/* Check if DMA is finished */
if (!dma_length && (cycles >= dma_endCycles))
{
/* Clear DMA Busy flag */
status &= 0xFFFD;
}
}
/* Return VDP status */
temp = status;
/* Clear pending flag */
pending = 0;
/* Clear SOVR & SCOL flags */
status &= 0xFF9F;
/* VBLANK flag is set when display is disabled */
if (!(reg[1] & 0x40))
{
temp |= 0x08;
}
/* Cycle-accurate VINT flag (Ex-Mutants, Tyrant / Mega-Lo-Mania) */
/* this allows VINT flag to be read just before vertical interrupt is being triggered */
if ((v_counter == bitmap.viewport.h) && (cycles >= (mcycles_vdp + 788)))
{
/* check Z80 interrupt state to assure VINT has not already been triggered (and flag cleared) */
if (Z80.irq_state != ASSERT_LINE)
{
temp |= 0x80;
}
}
/* Cycle-accurate HBLANK flag (Sonic 3 & Sonic 2 "VS Modes", Bugs Bunny Double Trouble, Lemmings 2, Mega Turrican, V.R Troopers, Gouketsuji Ichizoku,...) */
/* NB: this is not 100% accurate (see hvc.h for horizontal events timings in H32 and H40 mode) but is close enough to make no noticeable difference for games */
if ((cycles % MCYCLES_PER_LINE) < 588)
{
temp |= 0x04;
}
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] VDP 68k status read -> 0x%x (0x%x) (%x)\n", v_counter, (v_counter + (cycles - mcycles_vdp)/MCYCLES_PER_LINE)%lines_per_frame, cycles, cycles%MCYCLES_PER_LINE, temp, status, m68k_get_reg(M68K_REG_PC));
#endif
return (temp);
}
unsigned int vdp_z80_ctrl_r(unsigned int cycles)
{
unsigned int temp;
/* Check if DMA busy flag is set (Mega Drive VDP specific) */
if (status & 2)
{
/* Check if DMA is finished */
if (!dma_length && (cycles >= dma_endCycles))
{
/* Clear DMA Busy flag */
status &= 0xFD;
}
}
/* Check if we are already on next line */
if ((cycles - mcycles_vdp) >= MCYCLES_PER_LINE)
{
/* check vertical position */
if (v_counter == bitmap.viewport.h)
{
/* update VCounter to indicate VINT flag has been cleared & VINT should not be triggered */
v_counter++;
/* cycle-accurate VINT flag (immediately cleared after being read) */
status |= 0x80;
}
else
{
/* update line counter */
int line = (v_counter + 1) % lines_per_frame;
/* check if we are within active display range */
if ((line < bitmap.viewport.h) && !(work_ram[0x1ffb] & cart.special & HW_3D_GLASSES))
{
/* update VCounter to indicate next line has already been rendered */
v_counter = line;
/* render next line (cycle-accurate SCOL & SOVR flags) */
render_line(line);
}
}
}
/* Return VDP status */
temp = status;
/* Clear pending flag */
pending = 0;
/* Clear VINT, SOVR & SCOL flags */
status &= 0xFF1F;
/* Mega Drive VDP specific */
if (system_hw & SYSTEM_MD)
{
/* Display OFF: VBLANK flag is set */
if (!(reg[1] & 0x40))
{
temp |= 0x08;
}
/* HBLANK flag */
if ((cycles % MCYCLES_PER_LINE) < 588)
{
temp |= 0x04;
}
}
else if (reg[0] & 0x04)
{
/* Mode 4 unused bits (fixes PGA Tour Golf) */
temp |= 0x1F;
}
/* Cycle-accurate SCOL flag */
if ((temp & 0x20) && (v_counter == (spr_col >> 8)))
{
if (system_hw & SYSTEM_MD)
{
/* COL flag is set at HCount 0xFF on MD */
if ((cycles % MCYCLES_PER_LINE) < 105)
{
status |= 0x20;
temp &= ~0x20;
}
}
else
{
/* COL flag is set at the pixel it occurs */
uint8 hc = hctab[(cycles + SMS_CYCLE_OFFSET + 15) % MCYCLES_PER_LINE];
if ((hc < (spr_col & 0xff)) || (hc > 0xf3))
{
status |= 0x20;
temp &= ~0x20;
}
}
}
/* Clear HINT & VINT pending flags */
hint_pending = vint_pending = 0;
/* Clear Z80 interrupt */
Z80.irq_state = CLEAR_LINE;
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] VDP Z80 status read -> 0x%x (0x%x) (%x)\n", v_counter, (v_counter + (cycles - mcycles_vdp)/MCYCLES_PER_LINE)%lines_per_frame, cycles, cycles%MCYCLES_PER_LINE, temp, status, Z80.pc.w.l);
#endif
return (temp);
}
/*--------------------------------------------------------------------------*/
/* HV Counters */
/*--------------------------------------------------------------------------*/
unsigned int vdp_hvc_r(unsigned int cycles)
{
int vc;
unsigned int data = hvc_latch;
/* Check if HVC latch is enabled */
if (data)
{
/* Mode 5: HV counters are frozen (cf. lightgun games, Sunset Riders logo) */
if (reg[1] & 0x04)
{
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] HVC latch read -> 0x%x (%x)\n", v_counter, (v_counter + (cycles - mcycles_vdp)/MCYCLES_PER_LINE)%lines_per_frame, cycles, cycles%MCYCLES_PER_LINE, data & 0xffff, m68k_get_reg(M68K_REG_PC));
#endif
/* return latched HVC value */
return (data & 0xffff);
}
else
{
/* Mode 4: by default, VCounter runs normally & HCounter is frozen */
data &= 0xff;
}
}
else
{
/* Cycle-accurate HCounter (Striker, Mickey Mania, Skitchin, Road Rash I,II,III, Sonic 3D Blast...) */
data = hctab[cycles % MCYCLES_PER_LINE];
}
/* Cycle-accurate VCounter */
vc = v_counter;
if ((cycles - mcycles_vdp) >= MCYCLES_PER_LINE)
{
vc = (vc + 1) % lines_per_frame;
}
/* VCounter overflow */
if (vc > vc_max)
{
vc -= lines_per_frame;
}
/* Interlaced modes */
if (interlaced)
{
/* Interlace mode 2 (Sonic the Hedgehog 2, Combat Cars) */
vc <<= im2_flag;
/* Replace bit 0 with bit 8 */
vc = (vc & ~1) | ((vc >> 8) & 1);
}
/* return HCounter in LSB & VCounter in MSB */
data |= ((vc & 0xff) << 8);
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] HVC read -> 0x%x (%x)\n", v_counter, (v_counter + (cycles - mcycles_vdp)/MCYCLES_PER_LINE)%lines_per_frame, cycles, cycles%MCYCLES_PER_LINE, data, m68k_get_reg(M68K_REG_PC));
#endif
return (data);
}
/*--------------------------------------------------------------------------*/
/* Test registers */
/*--------------------------------------------------------------------------*/
void vdp_test_w(unsigned int data)
{
#ifdef LOGERROR
error("Unused VDP Write 0x%x (%08x)\n", data, m68k_get_reg(M68K_REG_PC));
#endif
}
/*--------------------------------------------------------------------------*/
/* 68k interrupt handler (TODO: check how interrupts are handled in Mode 4) */
/*--------------------------------------------------------------------------*/
int vdp_68k_irq_ack(int int_level)
{
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] INT Level %d ack (%x)\n", v_counter, (v_counter + (m68k.cycles - mcycles_vdp)/MCYCLES_PER_LINE)%lines_per_frame, m68k.cycles, m68k.cycles%MCYCLES_PER_LINE,int_level, m68k_get_reg(M68K_REG_PC));
#endif
/* VINT has higher priority (Fatal Rewind) */
if (reg[1] & vint_pending)
{
#ifdef LOGVDP
error("---> VINT cleared\n");
#endif
/* Clear VINT pending flag */
vint_pending = 0;
status &= ~0x80;
/* Update IRQ status */
if (reg[0] & hint_pending)
{
m68k_set_irq(4);
}
else
{
m68k_set_irq(0);
}
}
else
{
#ifdef LOGVDP
error("---> HINT cleared\n");
#endif
/* Clear HINT pending flag */
hint_pending = 0;
/* Update IRQ status */
m68k_set_irq(0);
}
return M68K_INT_ACK_AUTOVECTOR;
}
/*--------------------------------------------------------------------------*/
/* VDP registers update function */
/*--------------------------------------------------------------------------*/
static void vdp_reg_w(unsigned int r, unsigned int d, unsigned int cycles)
{
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] VDP register %d write -> 0x%x (%x)\n", v_counter, (v_counter + (cycles - mcycles_vdp)/MCYCLES_PER_LINE)%lines_per_frame, cycles, cycles%MCYCLES_PER_LINE, r, d, m68k_get_reg(M68K_REG_PC));
#endif
/* VDP registers #11 to #23 cannot be updated in Mode 4 (Captain Planet & Avengers, Bass Master Classic Pro Edition) */
if (!(reg[1] & 4) && (r > 10))
{
return;
}
switch(r)
{
case 0: /* CTRL #1 */
{
/* Look for changed bits */
r = d ^ reg[0];
reg[0] = d;
/* Line Interrupt */
if (r & hint_pending)
{
/* Update IRQ status */
if (reg[1] & vint_pending)
{
set_irq_line(6);
}
else if (d & 0x10)
{
set_irq_line_delay(4);
}
else
{
set_irq_line(0);
}
}
/* Palette selection */
if (r & 0x04)
{
/* Mega Drive VDP only */
if (system_hw & SYSTEM_MD)
{
/* Reset color palette */
int i;
if (reg[1] & 0x04)
{
/* Mode 5 */
color_update_m5(0x00, *(uint16 *)&cram[border << 1]);
for (i = 1; i < 0x40; i++)
{
color_update_m5(i, *(uint16 *)&cram[i << 1]);
}
}
else
{
/* Mode 4 */
for (i = 0; i < 0x20; i++)
{
color_update_m4(i, *(uint16 *)&cram[i << 1]);
}
color_update_m4(0x40, *(uint16 *)&cram[(0x10 | (border & 0x0F)) << 1]);
}
}
}
/* HVC latch (Sunset Riders, Lightgun games) */
if (r & 0x02)
{
/* Mega Drive VDP only */
if (system_hw & SYSTEM_MD)
{
/* Mode 5 only */
if (reg[1] & 0x04)
{
if (d & 0x02)
{
/* Latch current HVC */
hvc_latch = vdp_hvc_r(cycles) | 0x10000;
}
else
{
/* Free-running HVC */
hvc_latch = 0;
}
}
}
}
break;
}
case 1: /* CTRL #2 */
{
/* Look for changed bits */
r = d ^ reg[1];
reg[1] = d;
/* 4K/16K address decoding */
if (r & 0x80)
{
/* original TMS99xx hardware only (fixes Magical Kid Wiz) */
if (system_hw == SYSTEM_SG)
{
int i;
/* make temporary copy of 16KB VRAM */
memcpy(vram + 0x4000, vram, 0x4000);
/* re-arrange 16KB VRAM address decoding */
if (d & 0x80)
{
/* 4K->16K address decoding */
for (i=0; i<0x4000; i+=2)
{
*(uint16 *)(vram + ((i & 0x203F) | ((i << 6) & 0x1000) | ((i >> 1) & 0xFC0))) = *(uint16 *)(vram + 0x4000 + i);
}
}
else
{
/* 16K->4K address decoding */
for (i=0; i<0x4000; i+=2)
{
*(uint16 *)(vram + ((i & 0x203F) | ((i >> 6) & 0x40) | ((i << 1) & 0x1F80))) = *(uint16 *)(vram + 0x4000 + i);
}
}
}
}
/* Display status (modified during active display) */
if ((r & 0x40) && (v_counter < bitmap.viewport.h))
{
/* Cycle offset vs HBLANK */
int offset = cycles - mcycles_vdp;
if (offset <= 860)
{
/* Sprite rendering is limited if display was disabled during HBLANK (Mickey Mania 3d level, Overdrive Demo) */
if (d & 0x40)
{
/* NB: This is not 100% accurate. On real hardware, the maximal number of rendered sprites pixels */
/* for the current line (normally 256 or 320 pixels) but also the maximal number of pre-processed */
/* sprites for the next line (normally 64 or 80 sprites) are both reduced depending on the amount */
/* of cycles spent with display disabled. Here we only reduce them by a fixed amount when display */
/* has been reenabled after a specific point within HBLANK. */
if (offset > 360)
{
max_sprite_pixels = 128;
}
}
/* Redraw entire line (Legend of Galahad, Lemmings 2, Formula One, Kawasaki Super Bike, Deadly Moves,...) */
render_line(v_counter);
/* Restore default */
max_sprite_pixels = 256 + ((reg[12] & 1) << 6);
}
else if (system_hw & SYSTEM_MD)
{
/* Active pixel offset */
if (reg[12] & 1)
{
/* dot clock = MCLK / 8 */
offset = ((offset - 860) / 8) + 16;
}
else
{
/* dot clock = MCLK / 10 */
offset = ((offset - 860) / 10) + 16;
}
/* Line is partially blanked (Nigel Mansell's World Championship Racing , Ren & Stimpy Show, ...) */
if (offset < bitmap.viewport.w)
{
if (d & 0x40)
{
render_line(v_counter);
blank_line(v_counter, 0, offset);
}
else
{
blank_line(v_counter, offset, bitmap.viewport.w - offset);
}
}
}
}
/* Frame Interrupt */
if (r & vint_pending)
{
/* Update IRQ status */
if (d & 0x20)
{
set_irq_line_delay(6);
}
else if (reg[0] & hint_pending)
{
set_irq_line(4);
}
else
{
set_irq_line(0);
}
}
/* Active display height */
if (r & 0x08)
{
/* Mega Drive VDP only */
if (system_hw & SYSTEM_MD)
{
/* Mode 5 only */
if (d & 0x04)
{
/* Changes should be applied on next frame */
bitmap.viewport.changed |= 2;
/* Update vertical counter max value */
vc_max = vc_table[(d >> 2) & 3][vdp_pal];
}
}
}
/* Rendering mode */
if (r & 0x04)
{
/* Mega Drive VDP only */
if (system_hw & SYSTEM_MD)
{
int i;
if (d & 0x04)
{
/* Mode 5 rendering */
parse_satb = parse_satb_m5;
update_bg_pattern_cache = update_bg_pattern_cache_m5;
if (im2_flag)
{
render_bg = (reg[11] & 0x04) ? render_bg_m5_im2_vs : render_bg_m5_im2;
render_obj = (reg[12] & 0x08) ? render_obj_m5_im2_ste : render_obj_m5_im2;
}
else
{
render_bg = (reg[11] & 0x04) ? render_bg_m5_vs : render_bg_m5;
render_obj = (reg[12] & 0x08) ? render_obj_m5_ste : render_obj_m5;
}
/* Reset color palette */
color_update_m5(0x00, *(uint16 *)&cram[border << 1]);
for (i = 1; i < 0x40; i++)
{
color_update_m5(i, *(uint16 *)&cram[i << 1]);
}
/* Mode 5 bus access */
vdp_68k_data_w = vdp_68k_data_w_m5;
vdp_z80_data_w = vdp_z80_data_w_m5;
vdp_68k_data_r = vdp_68k_data_r_m5;
vdp_z80_data_r = vdp_z80_data_r_m5;
/* Clear HVC latched value */
hvc_latch = 0;
/* Check if HVC latch bit is set */
if (reg[0] & 0x02)
{
/* Latch current HVC */
hvc_latch = vdp_hvc_r(cycles) | 0x10000;
}
/* max tiles to invalidate */
bg_list_index = 0x800;
}
else
{
/* Mode 4 rendering */
parse_satb = parse_satb_m4;
update_bg_pattern_cache = update_bg_pattern_cache_m4;
render_bg = render_bg_m4;
render_obj = render_obj_m4;
/* Reset color palette */
for (i = 0; i < 0x20; i++)
{
color_update_m4(i, *(uint16 *)&cram[i << 1]);
}
color_update_m4(0x40, *(uint16 *)&cram[(0x10 | (border & 0x0F)) << 1]);
/* Mode 4 bus access */
vdp_68k_data_w = vdp_68k_data_w_m4;
vdp_z80_data_w = vdp_z80_data_w_m4;
vdp_68k_data_r = vdp_68k_data_r_m4;
vdp_z80_data_r = vdp_z80_data_r_m4;
/* Latch current HVC */
hvc_latch = vdp_hvc_r(cycles) | 0x10000;
/* max tiles to invalidate */
bg_list_index = 0x200;
}
/* Invalidate pattern cache */
for (i=0;i<bg_list_index;i++)
{
bg_name_list[i] = i;
bg_name_dirty[i] = 0xFF;
}
/* Update vertical counter max value */
vc_max = vc_table[(d >> 2) & 3][vdp_pal];
/* Display height change should be applied on next frame */
bitmap.viewport.changed |= 2;
}
else
{
/* No effect (cleared to avoid mode 5 detection elsewhere) */
reg[1] &= ~0x04;
}
}
break;
}
case 2: /* Plane A Name Table Base */
{
reg[2] = d;
ntab = (d << 10) & 0xE000;
/* Plane A Name Table Base changed during HBLANK */
if ((v_counter < bitmap.viewport.h) && (reg[1] & 0x40) && (cycles <= (mcycles_vdp + 860)))
{
/* render entire line */
render_line(v_counter);
}
break;
}
case 3: /* Window Plane Name Table Base */
{
reg[3] = d;
if (reg[12] & 0x01)
{
ntwb = (d << 10) & 0xF000;
}
else
{
ntwb = (d << 10) & 0xF800;
}
/* Window Plane Name Table Base changed during HBLANK */
if ((v_counter < bitmap.viewport.h) && (reg[1] & 0x40) && (cycles <= (mcycles_vdp + 860)))
{
/* render entire line */
render_line(v_counter);
}
break;
}
case 4: /* Plane B Name Table Base */
{
reg[4] = d;
ntbb = (d << 13) & 0xE000;
/* Plane B Name Table Base changed during HBLANK (Adventures of Batman & Robin) */
if ((v_counter < bitmap.viewport.h) && (reg[1] & 0x40) && (cycles <= (mcycles_vdp + 860)))
{
/* render entire line */
render_line(v_counter);
}
break;
}
case 5: /* Sprite Attribute Table Base */
{
reg[5] = d;
satb = (d << 9) & sat_base_mask;
break;
}
case 7: /* Backdrop color */
{
reg[7] = d;
/* Check if backdrop color changed */
d &= 0x3F;
if (d != border)
{
/* Update backdrop color */
border = d;
/* Reset palette entry */
if (reg[1] & 4)
{
/* Mode 5 */
color_update_m5(0x00, *(uint16 *)&cram[d << 1]);
}
else
{
/* Mode 4 */
color_update_m4(0x40, *(uint16 *)&cram[(0x10 | (d & 0x0F)) << 1]);
}
/* Backdrop color modified during HBLANK (Road Rash 1,2,3)*/
if ((v_counter < bitmap.viewport.h) && (cycles <= (mcycles_vdp + 860)))
{
/* remap entire line */
remap_line(v_counter);
}
}
break;
}
case 8: /* Horizontal Scroll (Mode 4 only) */
{
/* H-Scroll is latched at HCount 0xF3, HCount 0xF6 on MD */
/* Line starts at HCount 0xF4, HCount 0xF6 on MD */
if (system_hw < SYSTEM_MD)
{
cycles = cycles + 15;
}
/* Check if H-Scroll has already been latched */
if ((cycles - mcycles_vdp) >= MCYCLES_PER_LINE)
{
/* update line counter */
int line = (v_counter + 1) % lines_per_frame;
/* check if we are within active display range */
if ((line < bitmap.viewport.h) && !(work_ram[0x1ffb] & cart.special & HW_3D_GLASSES))
{
/* update VCounter to indicate next line has already been rendered */
v_counter = line;
/* render next line before updating H-Scroll */
render_line(line);
}
}
reg[8] = d;
break;
}
case 11: /* CTRL #3 */
{
reg[11] = d;
/* Horizontal scrolling mode */
hscroll_mask = hscroll_mask_table[d & 0x03];
/* Vertical Scrolling mode */
if (d & 0x04)
{
render_bg = im2_flag ? render_bg_m5_im2_vs : render_bg_m5_vs;
}
else
{
render_bg = im2_flag ? render_bg_m5_im2 : render_bg_m5;
}
break;
}
case 12: /* CTRL #4 */
{
/* Look for changed bits */
r = d ^ reg[12];
reg[12] = d;
/* Shadow & Highlight mode */
if (r & 0x08)
{
/* Reset color palette */
int i;
color_update_m5(0x00, *(uint16 *)&cram[border << 1]);
for (i = 1; i < 0x40; i++)
{
color_update_m5(i, *(uint16 *)&cram[i << 1]);
}
/* Update sprite rendering function */
if (d & 0x08)
{
render_obj = im2_flag ? render_obj_m5_im2_ste : render_obj_m5_ste;
}
else
{
render_obj = im2_flag ? render_obj_m5_im2 : render_obj_m5;
}
}
/* Interlaced modes */
if (r & 0x06)
{
/* changes should be applied on next frame */
bitmap.viewport.changed |= 2;
}
/* Active display width */
if (r & 0x01)
{
if (d & 0x01)
{
/* Update display-dependant registers */
ntwb = (reg[3] << 10) & 0xF000;
satb = (reg[5] << 9) & 0xFC00;
sat_base_mask = 0xFC00;
sat_addr_mask = 0x03FF;
/* Update HC table */
hctab = cycle2hc40;
/* Update clipping */
window_clip(reg[17], 1);
/* Update max sprite pixels per line*/
max_sprite_pixels = 320;
}
else
{
/* Update display-dependant registers */
ntwb = (reg[3] << 10) & 0xF800;
satb = (reg[5] << 9) & 0xFE00;
sat_base_mask = 0xFE00;
sat_addr_mask = 0x01FF;
/* Update HC table */
hctab = cycle2hc32;
/* Update clipping */
window_clip(reg[17], 0);
/* Update max sprite pixels per line*/
max_sprite_pixels = 256;
}
if (v_counter >= bitmap.viewport.h)
{
/* Active screen width modified during VBLANK will be applied on upcoming frame */
bitmap.viewport.w = max_sprite_pixels;
}
else if ((v_counter == 0) && (cycles <= (mcycles_vdp + 860)))
{
/* Active screen width modified during first line HBLANK (Bugs Bunny in Double Trouble) */
bitmap.viewport.w = max_sprite_pixels;
/* Redraw first line */
render_line(0);
}
else
{
/* Screen width changes during active display (Golden Axe 3 intro, Ultraverse Prime) */
/* should be applied on next frame since backend rendered framebuffer width is fixed */
/* and can not be modified mid-frame. This is not 100% accurate but games generally */
/* do this where the screen is blanked so it is likely unnoticeable. */
bitmap.viewport.changed |= 2;
}
}
break;
}
case 13: /* HScroll Base Address */
{
reg[13] = d;
hscb = (d << 10) & 0xFC00;
break;
}
case 16: /* Playfield size */
{
reg[16] = d;
playfield_shift = shift_table[(d & 3)];
playfield_col_mask = col_mask_table[(d & 3)];
playfield_row_mask = row_mask_table[(d >> 4) & 3];
break;
}
case 17: /* Window/Plane A vertical clipping */
{
reg[17] = d;
window_clip(d, reg[12] & 1);
break;
}
default:
{
reg[r] = d;
break;
}
}
}
/*--------------------------------------------------------------------------*/
/* FIFO emulation (Mega Drive VDP specific) */
/* ---------------------------------------- */
/* */
/* CPU access to VRAM, CRAM & VSRAM is limited during active display: */
/* H32 mode -> 16 access per line */
/* H40 mode -> 18 access per line */
/* */
/* with fixed access slots timings detailled below. */
/* */
/* Each VRAM access is byte wide, so one VRAM write (word) need two slots. */
/* */
/*--------------------------------------------------------------------------*/
static void vdp_fifo_update(unsigned int cycles)
{
int num, slots, count = 0;
const int *fifo_timing;
const int fifo_cycles_h32[16+4] =
{
230, 510, 810, 970, 1130, 1450, 1610, 1770, 2090, 2250, 2410, 2730, 2890, 3050, 3350, 3370,
MCYCLES_PER_LINE + 230, MCYCLES_PER_LINE + 510, MCYCLES_PER_LINE + 810, MCYCLES_PER_LINE + 970,
};
const int fifo_cycles_h40[18+4] =
{
352, 820, 948, 1076, 1332, 1460, 1588, 1844, 1972, 2100, 2356, 2484, 2612, 2868, 2996, 3124, 3364, 3380,
MCYCLES_PER_LINE + 352, MCYCLES_PER_LINE + 820, MCYCLES_PER_LINE + 948, MCYCLES_PER_LINE + 1076,
};
/* number of access slots up to current line */
if (reg[12] & 0x01)
{
fifo_timing = fifo_cycles_h40;
slots = 18 * ((v_counter + 1) % lines_per_frame);
}
else
{
fifo_timing = fifo_cycles_h32;
slots = 16 * ((v_counter + 1) % lines_per_frame);
}
/* number of access slots within current line */
cycles -= mcycles_vdp;
while (fifo_timing[count] <= cycles)
{
count++;
}
/* number of processed FIFO entries since last access (byte access needs two slots to process one FIFO word) */
num = (slots + count - fifo_slots) >> fifo_byte_access;
if (num > 0)
{
/* process FIFO entries */
fifo_write_cnt -= num;
/* Clear FIFO full flag */
status &= 0xFEFF;
if (fifo_write_cnt <= 0)
{
/* No more FIFO entries */
fifo_write_cnt = 0;
/* Set FIFO empty flag */
status |= 0x200;
/* Reinitialize FIFO access slot counter */
fifo_slots = slots + count;
}
else
{
/* Update FIFO access slot counter */
fifo_slots += (num << fifo_byte_access);
}
}
/* next FIFO update cycle */
fifo_cycles = mcycles_vdp + fifo_timing[fifo_slots - slots + fifo_byte_access];
}
/*--------------------------------------------------------------------------*/
/* Internal 16-bit data bus access function (Mode 5 only) */
/*--------------------------------------------------------------------------*/
static void vdp_bus_w(unsigned int data)
{
/* write data to next FIFO entry */
fifo[fifo_idx] = data;
/* increment FIFO write pointer */
fifo_idx = (fifo_idx + 1) & 3;
/* Check destination code (CD0-CD3) */
switch (code & 0x0F)
{
case 0x01: /* VRAM */
{
/* VRAM address */
int index = addr & 0xFFFE;
/* Pointer to VRAM */
uint16 *p = (uint16 *)&vram[index];
/* Byte-swap data if A0 is set */
if (addr & 1)
{
data = ((data >> 8) | (data << 8)) & 0xFFFF;
}
/* Intercept writes to Sprite Attribute Table */
if ((index & sat_base_mask) == satb)
{
/* Update internal SAT */
*(uint16 *) &sat[index & sat_addr_mask] = data;
}
/* Only write unique data to VRAM */
if (data != *p)
{
int name;
/* Write data to VRAM */
*p = data;
/* Update pattern cache */
MARK_BG_DIRTY (index);
}
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] VRAM 0x%x write -> 0x%x (%x)\n", v_counter, (v_counter + (m68k.cycles - mcycles_vdp)/MCYCLES_PER_LINE)%lines_per_frame, m68k.cycles, m68k.cycles%MCYCLES_PER_LINE, addr, data, m68k_get_reg(M68K_REG_PC));
#endif
break;
}
case 0x03: /* CRAM */
{
/* Pointer to CRAM 9-bit word */
uint16 *p = (uint16 *)&cram[addr & 0x7E];
/* Pack 16-bit bus data (BBB0GGG0RRR0) to 9-bit CRAM data (BBBGGGRRR) */
data = ((data & 0xE00) >> 3) | ((data & 0x0E0) >> 2) | ((data & 0x00E) >> 1);
/* Check if CRAM data is being modified */
if (data != *p)
{
/* CRAM index (64 words) */
int index = (addr >> 1) & 0x3F;
/* Write CRAM data */
*p = data;
/* Color entry 0 of each palette is never displayed (transparent pixel) */
if (index & 0x0F)
{
/* Update color palette */
color_update_m5(index, data);
}
/* Update backdrop color */
if (index == border)
{
color_update_m5(0x00, data);
}
/* CRAM modified during HBLANK (Striker, Zero the Kamikaze, etc) */
if ((v_counter < bitmap.viewport.h) && (reg[1] & 0x40) && (m68k.cycles <= (mcycles_vdp + 860)))
{
/* Remap current line */
remap_line(v_counter);
}
}
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] CRAM 0x%x write -> 0x%x (%x)\n", v_counter, (v_counter + (m68k.cycles - mcycles_vdp)/MCYCLES_PER_LINE)%lines_per_frame, m68k.cycles, m68k.cycles%MCYCLES_PER_LINE, addr, data, m68k_get_reg(M68K_REG_PC));
#endif
break;
}
case 0x05: /* VSRAM */
{
*(uint16 *)&vsram[addr & 0x7E] = data;
/* 2-cell Vscroll mode */
if (reg[11] & 0x04)
{
/* VSRAM writes during HBLANK (Adventures of Batman & Robin) */
if ((v_counter < bitmap.viewport.h) && (reg[1] & 0x40) && (m68k.cycles <= (mcycles_vdp + 860)))
{
/* Redraw entire line */
render_line(v_counter);
}
}
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] VSRAM 0x%x write -> 0x%x (%x)\n", v_counter, (v_counter + (m68k.cycles - mcycles_vdp)/MCYCLES_PER_LINE)%lines_per_frame, m68k.cycles, m68k.cycles%MCYCLES_PER_LINE, addr, data, m68k_get_reg(M68K_REG_PC));
#endif
break;
}
default:
{
/* add some delay until 68k periodical wait-states are accurately emulated ("Clue", "Microcosm") */
m68k.cycles += 2;
#ifdef LOGERROR
error("[%d(%d)][%d(%d)] Invalid (%d) 0x%x write -> 0x%x (%x)\n", v_counter, (v_counter + (m68k.cycles - mcycles_vdp)/MCYCLES_PER_LINE)%lines_per_frame, m68k.cycles, m68k.cycles%MCYCLES_PER_LINE, code, addr, data, m68k_get_reg(M68K_REG_PC));
#endif
break;
}
}
/* Increment address register */
addr += reg[15];
}
/*--------------------------------------------------------------------------*/
/* 68k bus interface (Mega Drive VDP only) */
/*--------------------------------------------------------------------------*/
static void vdp_68k_data_w_m4(unsigned int data)
{
/* Clear pending flag */
pending = 0;
/* Restricted VDP writes during active display */
if (!(status & 8) && (reg[1] & 0x40))
{
/* Update VDP FIFO */
vdp_fifo_update(m68k.cycles);
/* Clear FIFO empty flag */
status &= 0xFDFF;
/* up to 4 words can be stored */
if (fifo_write_cnt < 4)
{
/* Increment FIFO counter */
fifo_write_cnt++;
/* Set FIFO full flag if 4 words are stored */
status |= ((fifo_write_cnt & 4) << 6);
}
else
{
/* CPU is halted until next FIFO entry processing */
m68k.cycles = fifo_cycles;
/* Update FIFO access slot counter */
fifo_slots += (fifo_byte_access + 1);
}
}
/* Check destination code */
if (code & 0x02)
{
/* CRAM index (32 words) */
int index = addr & 0x1F;
/* Pointer to CRAM 9-bit word */
uint16 *p = (uint16 *)&cram[index << 1];
/* Pack 16-bit data (xxx000BBGGRR) to 9-bit CRAM data (xxxBBGGRR) */
data = ((data & 0xE00) >> 3) | (data & 0x3F);
/* Check if CRAM data is being modified */
if (data != *p)
{
/* Write CRAM data */
*p = data;
/* Update color palette */
color_update_m4(index, data);
/* Update backdrop color */
if (index == (0x10 | (border & 0x0F)))
{
color_update_m4(0x40, data);
}
}
}
else
{
/* VRAM address (interleaved format) */
int index = ((addr << 1) & 0x3FC) | ((addr & 0x200) >> 8) | (addr & 0x3C00);
/* Pointer to VRAM */
uint16 *p = (uint16 *)&vram[index];
/* Byte-swap data if A0 is set */
if (addr & 1)
{
data = ((data >> 8) | (data << 8)) & 0xFFFF;
}
/* Only write unique data to VRAM */
if (data != *p)
{
int name;
/* Write data to VRAM */
*p = data;
/* Update the pattern cache */
MARK_BG_DIRTY (index);
}
}
/* Increment address register (TODO: check how address is incremented in Mode 4) */
addr += (reg[15] + 1);
}
static void vdp_68k_data_w_m5(unsigned int data)
{
/* Clear pending flag */
pending = 0;
/* Restricted VDP writes during active display */
if (!(status & 8) && (reg[1] & 0x40))
{
/* Update VDP FIFO */
vdp_fifo_update(m68k.cycles);
/* Clear FIFO empty flag */
status &= 0xFDFF;
/* up to 4 words can be stored */
if (fifo_write_cnt < 4)
{
/* Increment FIFO counter */
fifo_write_cnt++;
/* Set FIFO full flag if 4 words are stored */
status |= ((fifo_write_cnt & 4) << 6);
}
else
{
/* CPU is halted until next FIFO entry processing (Chaos Engine / Soldiers of Fortune, Double Clutch, Titan Overdrive Demo) */
m68k.cycles = fifo_cycles;
/* Update FIFO access slot counter */
fifo_slots += (fifo_byte_access + 1);
}
}
/* Write data */
vdp_bus_w(data);
/* Check if DMA Fill is pending */
if (dmafill)
{
/* Clear DMA Fill pending flag */
dmafill = 0;
/* DMA length */
dma_length = (reg[20] << 8) | reg[19];
/* Zero DMA length (pre-decrementing counter) */
if (!dma_length)
{
dma_length = 0x10000;
}
/* Trigger DMA */
vdp_dma_update(m68k.cycles);
}
}
static unsigned int vdp_68k_data_r_m4(void)
{
/* VRAM address (interleaved format) */
int index = ((addr << 1) & 0x3FC) | ((addr & 0x200) >> 8) | (addr & 0x3C00);
/* Clear pending flag */
pending = 0;
/* Increment address register (TODO: check how address is incremented in Mode 4) */
addr += (reg[15] + 1);
/* Read VRAM data */
return *(uint16 *) &vram[index];
}
static unsigned int vdp_68k_data_r_m5(void)
{
uint16 data = 0;
/* Clear pending flag */
pending = 0;
/* Check destination code (CD0-CD3) & CD4 */
switch (code & 0x1F)
{
case 0x00:
{
/* read two bytes from VRAM */
data = *(uint16 *)&vram[addr & 0xFFFE];
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] VRAM 0x%x read -> 0x%x (%x)\n", v_counter, (v_counter + (m68k.cycles - mcycles_vdp)/MCYCLES_PER_LINE)%lines_per_frame, m68k.cycles, m68k.cycles%MCYCLES_PER_LINE, addr, data, m68k_get_reg(M68K_REG_PC));
#endif
break;
}
case 0x04:
{
/* VSRAM index */
int index = addr & 0x7E;
/* Check against VSRAM max size (80 x 11-bits) */
if (index >= 0x50)
{
/* Wrap to address 0 (TODO: check if still true with Genesis 3 model) */
index = 0;
}
/* Read 11-bit word from VSRAM */
data = *(uint16 *)&vsram[index] & 0x7FF;
/* Unused bits are set using data from next available FIFO entry */
data |= (fifo[fifo_idx] & ~0x7FF);
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] VSRAM 0x%x read -> 0x%x (%x)\n", v_counter, (v_counter + (m68k.cycles - mcycles_vdp)/MCYCLES_PER_LINE)%lines_per_frame, m68k.cycles, m68k.cycles%MCYCLES_PER_LINE, addr, data, m68k_get_reg(M68K_REG_PC));
#endif
break;
}
case 0x08:
{
/* Read 9-bit word from CRAM */
data = *(uint16 *)&cram[addr & 0x7E];
/* Unpack 9-bit CRAM data (BBBGGGRRR) to 16-bit bus data (BBB0GGG0RRR0) */
data = ((data & 0x1C0) << 3) | ((data & 0x038) << 2) | ((data & 0x007) << 1);
/* Unused bits are set using data from next available FIFO entry */
data |= (fifo[fifo_idx] & ~0xEEE);
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] CRAM 0x%x read -> 0x%x (%x)\n", v_counter, (v_counter + (m68k.cycles - mcycles_vdp)/MCYCLES_PER_LINE)%lines_per_frame, m68k.cycles, m68k.cycles%MCYCLES_PER_LINE, addr, data, m68k_get_reg(M68K_REG_PC));
#endif
break;
}
case 0x0c: /* undocumented 8-bit VRAM read */
{
/* Read one byte from VRAM adjacent address */
data = READ_BYTE(vram, addr ^ 1);
/* Unused bits are set using data from next available FIFO entry */
data |= (fifo[fifo_idx] & ~0xFF);
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] 8-bit VRAM 0x%x read -> 0x%x (%x)\n", v_counter, (v_counter + (m68k.cycles - mcycles_vdp)/MCYCLES_PER_LINE)%lines_per_frame, m68k.cycles, m68k.cycles%MCYCLES_PER_LINE, addr, data, m68k_get_reg(M68K_REG_PC));
#endif
break;
}
default:
{
/* Invalid code value (normally locks VDP, hard reset required) */
#ifdef LOGERROR
error("[%d(%d)][%d(%d)] Invalid (%d) 0x%x read (%x)\n", v_counter, (v_counter + (m68k.cycles - mcycles_vdp)/MCYCLES_PER_LINE)%lines_per_frame, m68k.cycles, m68k.cycles%MCYCLES_PER_LINE, code, addr, m68k_get_reg(M68K_REG_PC));
#endif
break;
}
}
/* Increment address register */
addr += reg[15];
/* Return data */
return data;
}
/*--------------------------------------------------------------------------*/
/* Z80 bus interface (Mega Drive VDP in Master System compatibility mode) */
/*--------------------------------------------------------------------------*/
static void vdp_z80_data_w_m4(unsigned int data)
{
/* Clear pending flag */
pending = 0;
/* Check destination code */
if (code & 0x02)
{
/* CRAM index (32 words) */
int index = addr & 0x1F;
/* Pointer to CRAM word */
uint16 *p = (uint16 *)&cram[index << 1];
/* Check if CRAM data is being modified */
if (data != *p)
{
/* Write CRAM data */
*p = data;
/* Update color palette */
color_update_m4(index, data);
/* Update backdrop color */
if (index == (0x10 | (border & 0x0F)))
{
color_update_m4(0x40, data);
}
}
}
else
{
/* VRAM address */
int index = addr & 0x3FFF;
/* Only write unique data to VRAM */
if (data != vram[index])
{
int name;
/* Write data */
vram[index] = data;
/* Update pattern cache */
MARK_BG_DIRTY(index);
}
}
/* Increment address register (TODO: check how address is incremented in Mode 4) */
addr += (reg[15] + 1);
}
static void vdp_z80_data_w_m5(unsigned int data)
{
/* Clear pending flag */
pending = 0;
/* Push byte into FIFO */
fifo[fifo_idx] = data << 8;
fifo_idx = (fifo_idx + 1) & 3;
/* Check destination code (CD0-CD3) */
switch (code & 0x0F)
{
case 0x01: /* VRAM */
{
/* VRAM address (write low byte to even address & high byte to odd address) */
int index = addr ^ 1;
/* Intercept writes to Sprite Attribute Table */
if ((index & sat_base_mask) == satb)
{
/* Update internal SAT */
WRITE_BYTE(sat, index & sat_addr_mask, data);
}
/* Only write unique data to VRAM */
if (data != READ_BYTE(vram, index))
{
int name;
/* Write data */
WRITE_BYTE(vram, index, data);
/* Update pattern cache */
MARK_BG_DIRTY (index);
}
break;
}
case 0x03: /* CRAM */
{
/* Pointer to CRAM word */
uint16 *p = (uint16 *)&cram[addr & 0x7E];
/* Pack 8-bit value into 9-bit CRAM data */
if (addr & 1)
{
/* Write high byte (0000BBB0 -> BBBxxxxxx) */
data = (*p & 0x3F) | ((data & 0x0E) << 5);
}
else
{
/* Write low byte (GGG0RRR0 -> xxxGGGRRR) */
data = (*p & 0x1C0) | ((data & 0x0E) >> 1)| ((data & 0xE0) >> 2);
}
/* Check if CRAM data is being modified */
if (data != *p)
{
/* CRAM index (64 words) */
int index = (addr >> 1) & 0x3F;
/* Write CRAM data */
*p = data;
/* Color entry 0 of each palette is never displayed (transparent pixel) */
if (index & 0x0F)
{
/* Update color palette */
color_update_m5(index, data);
}
/* Update backdrop color */
if (index == border)
{
color_update_m5(0x00, data);
}
}
break;
}
case 0x05: /* VSRAM */
{
/* Write low byte to even address & high byte to odd address */
WRITE_BYTE(vsram, (addr & 0x7F) ^ 1, data);
break;
}
}
/* Increment address register */
addr += reg[15];
/* Check if DMA Fill is pending */
if (dmafill)
{
/* Clear DMA Fill pending flag */
dmafill = 0;
/* DMA length */
dma_length = (reg[20] << 8) | reg[19];
/* Zero DMA length (pre-decrementing counter) */
if (!dma_length)
{
dma_length = 0x10000;
}
/* Trigger DMA */
vdp_dma_update(Z80.cycles);
}
}
static unsigned int vdp_z80_data_r_m4(void)
{
/* Read buffer */
unsigned int data = fifo[0];
/* Clear pending flag */
pending = 0;
/* Process next read */
fifo[0] = vram[addr & 0x3FFF];
/* Increment address register (TODO: check how address is incremented with Mega Drive VDP in Mode 4) */
addr += (reg[15] + 1);
/* Return data */
return data;
}
static unsigned int vdp_z80_data_r_m5(void)
{
unsigned int data = 0;
/* Clear pending flag */
pending = 0;
/* Check destination code (CD0-CD3) & CD4 */
switch (code & 0x1F)
{
case 0x00: /* VRAM */
{
/* Return low byte from even address & high byte from odd address */
data = READ_BYTE(vram, addr ^ 1);
break;
}
case 0x04: /* VSRAM */
{
/* Return low byte from even address & high byte from odd address */
data = READ_BYTE(vsram, (addr & 0x7F) ^ 1);
break;
}
case 0x08: /* CRAM */
{
/* Read CRAM data */
data = *(uint16 *)&cram[addr & 0x7E];
/* Unpack 9-bit CRAM data (BBBGGGRRR) to 16-bit data (BBB0GGG0RRR0) */
data = ((data & 0x1C0) << 3) | ((data & 0x038) << 2) | ((data & 0x007) << 1);
/* Return low byte from even address & high byte from odd address */
if (addr & 1)
{
data = data >> 8;
}
data &= 0xFF;
break;
}
}
/* Increment address register */
addr += reg[15];
/* Return data */
return data;
}
/*-----------------------------------------------------------------------------*/
/* Z80 bus interface (Master System, Game Gear & SG-1000 VDP) */
/*-----------------------------------------------------------------------------*/
static void vdp_z80_data_w_ms(unsigned int data)
{
/* Clear pending flag */
pending = 0;
if (code < 3)
{
int index;
/* Check if we are already on next line */
if ((Z80.cycles - mcycles_vdp) >= MCYCLES_PER_LINE)
{
/* update line counter */
int line = (v_counter + 1) % lines_per_frame;
/* check if we are within active display range */
if ((line < bitmap.viewport.h) && !(work_ram[0x1ffb] & cart.special & HW_3D_GLASSES))
{
/* update VCounter to indicate next line has already been rendered */
v_counter = line;
/* render next line */
render_line(line);
}
}
/* VRAM address */
index = addr & 0x3FFF;
/* VRAM write */
if (data != vram[index])
{
int name;
vram[index] = data;
MARK_BG_DIRTY(index);
}
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] VRAM 0x%x write -> 0x%x (%x)\n", v_counter, (v_counter + (Z80.cycles - mcycles_vdp)/MCYCLES_PER_LINE)%lines_per_frame, Z80.cycles, Z80.cycles%MCYCLES_PER_LINE, index, data, Z80.pc.w.l);
#endif
}
else
{
/* CRAM address */
int index = addr & 0x1F;
/* Pointer to CRAM word */
uint16 *p = (uint16 *)&cram[index << 1];
/* Check if CRAM data is being modified */
if (data != *p)
{
/* Write CRAM data */
*p = data;
/* Update color palette */
color_update_m4(index, data);
/* Update backdrop color */
if (index == (0x10 | (border & 0x0F)))
{
color_update_m4(0x40, data);
}
}
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] CRAM 0x%x write -> 0x%x (%x)\n", v_counter, (v_counter + (Z80.cycles - mcycles_vdp)/MCYCLES_PER_LINE)%lines_per_frame, Z80.cycles, Z80.cycles%MCYCLES_PER_LINE, addr, data, Z80.pc.w.l);
#endif
}
/* Update read buffer */
fifo[0] = data;
/* Update address register */
addr++;
}
static void vdp_z80_data_w_gg(unsigned int data)
{
/* Clear pending flag */
pending = 0;
if (code < 3)
{
int index;
/* Check if we are already on next line */
if ((Z80.cycles - mcycles_vdp) >= MCYCLES_PER_LINE)
{
/* update line counter */
int line = (v_counter + 1) % lines_per_frame;
/* check if we are within active display range */
if ((line < bitmap.viewport.h) && !(work_ram[0x1ffb] & cart.special & HW_3D_GLASSES))
{
/* update VCounter to indicate next line has already been rendered */
v_counter = line;
/* render next line */
render_line(line);
}
}
/* VRAM address */
index = addr & 0x3FFF;
/* VRAM write */
if (data != vram[index])
{
int name;
vram[index] = data;
MARK_BG_DIRTY(index);
}
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] VRAM 0x%x write -> 0x%x (%x)\n", v_counter, (v_counter + (Z80.cycles - mcycles_vdp)/MCYCLES_PER_LINE)%lines_per_frame, Z80.cycles, Z80.cycles%MCYCLES_PER_LINE, index, data, Z80.pc.w.l);
#endif
}
else
{
if (addr & 1)
{
/* Pointer to CRAM word */
uint16 *p = (uint16 *)&cram[addr & 0x3E];
/* 12-bit data word */
data = (data << 8) | cached_write;
/* Check if CRAM data is being modified */
if (data != *p)
{
/* Color index (0-31) */
int index = (addr >> 1) & 0x1F;
/* Write CRAM data */
*p = data;
/* Update color palette */
color_update_m4(index, data);
/* Update backdrop color */
if (index == (0x10 | (border & 0x0F)))
{
color_update_m4(0x40, data);
}
}
}
else
{
/* Latch LSB */
cached_write = data;
}
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] CRAM 0x%x write -> 0x%x (%x)\n", v_counter, (v_counter + (Z80.cycles - mcycles_vdp)/MCYCLES_PER_LINE)%lines_per_frame, Z80.cycles, Z80.cycles%MCYCLES_PER_LINE, addr, data, Z80.pc.w.l);
#endif
}
/* Update read buffer */
fifo[0] = data;
/* Update address register */
addr++;
}
static void vdp_z80_data_w_sg(unsigned int data)
{
/* VRAM address */
int index = addr & 0x3FFF;
/* Clear pending flag */
pending = 0;
/* VRAM write */
vram[index] = data;
/* Update address register */
addr++;
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] VRAM 0x%x write -> 0x%x (%x)\n", v_counter, (v_counter + (Z80.cycles - mcycles_vdp)/MCYCLES_PER_LINE)%lines_per_frame, Z80.cycles, Z80.cycles%MCYCLES_PER_LINE, index, data, Z80.pc.w.l);
#endif
}
/*--------------------------------------------------------------------------*/
/* DMA operations (Mega Drive VDP only) */
/*--------------------------------------------------------------------------*/
/* DMA from 68K bus: $000000-$7FFFFF (external area) */
static void vdp_dma_68k_ext(unsigned int length)
{
uint16 data;
/* 68k bus source address */
uint32 source = (reg[23] << 17) | (dma_src << 1);
do
{
/* Read data word from 68k bus */
if (m68k.memory_map[source>>16].read16)
{
data = m68k.memory_map[source>>16].read16(source);
}
else
{
data = *(uint16 *)(m68k.memory_map[source>>16].base + (source & 0xFFFF));
}
/* Increment source address */
source += 2;
/* 128k DMA window */
source = (reg[23] << 17) | (source & 0x1FFFF);
/* Write data word to VRAM, CRAM or VSRAM */
vdp_bus_w(data);
}
while (--length);
/* Update DMA source address */
dma_src = (source >> 1) & 0xffff;
}
/* DMA from 68K bus: $800000-$FFFFFF (internal area) except I/O area */
static void vdp_dma_68k_ram(unsigned int length)
{
uint16 data;
/* 68k bus source address */
uint32 source = (reg[23] << 17) | (dma_src << 1);
do
{
/* access Work-RAM by default */
data = *(uint16 *)(work_ram + (source & 0xFFFF));
/* Increment source address */
source += 2;
/* 128k DMA window */
source = (reg[23] << 17) | (source & 0x1FFFF);
/* Write data word to VRAM, CRAM or VSRAM */
vdp_bus_w(data);
}
while (--length);
/* Update DMA source address */
dma_src = (source >> 1) & 0xffff;
}
/* DMA from 68K bus: $A00000-$A1FFFF (I/O area) specific */
static void vdp_dma_68k_io(unsigned int length)
{
uint16 data;
/* 68k bus source address */
uint32 source = (reg[23] << 17) | (dma_src << 1);
do
{
/* Z80 area */
if (source <= 0xA0FFFF)
{
/* Return $FFFF only when the Z80 isn't hogging the Z-bus.
(e.g. Z80 isn't reset and 68000 has the bus) */
data = ((zstate ^ 3) ? *(uint16 *)(work_ram + (source & 0xFFFF)) : 0xFFFF);
}
/* The I/O chip and work RAM try to drive the data bus which results
in both values being combined in random ways when read.
We return the I/O chip values which seem to have precedence, */
else if (source <= 0xA1001F)
{
data = io_68k_read((source >> 1) & 0x0F);
data = (data << 8 | data);
}
/* All remaining locations access work RAM */
else
{
data = *(uint16 *)(work_ram + (source & 0xFFFF));
}
/* Increment source address */
source += 2;
/* 128k DMA window */
source = (reg[23] << 17) | (source & 0x1FFFF);
/* Write data to VRAM, CRAM or VSRAM */
vdp_bus_w(data);
}
while (--length);
/* Update DMA source address */
dma_src = (source >> 1) & 0xffff;
}
/* VRAM Copy */
static void vdp_dma_copy(unsigned int length)
{
/* CD4 should be set (CD0-CD3 ignored) otherwise VDP locks (hard reset needed) */
if (code & 0x10)
{
int name;
uint8 data;
/* VRAM source address */
uint16 source = dma_src;
do
{
/* Read byte from adjacent VRAM source address */
data = READ_BYTE(vram, source ^ 1);
/* Intercept writes to Sprite Attribute Table */
if ((addr & sat_base_mask) == satb)
{
/* Update internal SAT */
WRITE_BYTE(sat, (addr & sat_addr_mask) ^ 1, data);
}
/* Write byte to adjacent VRAM destination address */
WRITE_BYTE(vram, addr ^ 1, data);
/* Update pattern cache */
MARK_BG_DIRTY(addr);
/* Increment VRAM source address */
source++;
/* Increment VRAM destination address */
addr += reg[15];
}
while (--length);
/* Update DMA source address */
dma_src = source;
}
}
/* DMA Fill */
static void vdp_dma_fill(unsigned int length)
{
/* Check destination code (CD0-CD3) */
switch (code & 0x0F)
{
case 0x01: /* VRAM */
{
int name;
/* Get source data from last written FIFO entry */
uint8 data = fifo[(fifo_idx+3)&3] >> 8;
do
{
/* Intercept writes to Sprite Attribute Table */
if ((addr & sat_base_mask) == satb)
{
/* Update internal SAT */
WRITE_BYTE(sat, (addr & sat_addr_mask) ^ 1, data);
}
/* Write byte to adjacent VRAM address */
WRITE_BYTE(vram, addr ^ 1, data);
/* Update pattern cache */
MARK_BG_DIRTY (addr);
/* Increment VRAM address */
addr += reg[15];
}
while (--length);
break;
}
case 0x03: /* CRAM */
{
/* Get source data from next available FIFO entry */
uint16 data = fifo[fifo_idx];
/* Pack 16-bit bus data (BBB0GGG0RRR0) to 9-bit CRAM data (BBBGGGRRR) */
data = ((data & 0xE00) >> 3) | ((data & 0x0E0) >> 2) | ((data & 0x00E) >> 1);
do
{
/* Pointer to CRAM 9-bit word */
uint16 *p = (uint16 *)&cram[addr & 0x7E];
/* Check if CRAM data is being modified */
if (data != *p)
{
/* CRAM index (64 words) */
int index = (addr >> 1) & 0x3F;
/* Write CRAM data */
*p = data;
/* Color entry 0 of each palette is never displayed (transparent pixel) */
if (index & 0x0F)
{
/* Update color palette */
color_update_m5(index, data);
}
/* Update backdrop color */
if (index == border)
{
color_update_m5(0x00, data);
}
}
/* Increment CRAM address */
addr += reg[15];
}
while (--length);
break;
}
case 0x05: /* VSRAM */
{
/* Get source data from next available FIFO entry */
uint16 data = fifo[fifo_idx];
do
{
/* Write VSRAM data */
*(uint16 *)&vsram[addr & 0x7E] = data;
/* Increment VSRAM address */
addr += reg[15];
}
while (--length);
break;
}
default:
{
/* invalid destination does nothing (Williams Greatest Hits after soft reset) */
/* address is still incremented */
addr += reg[15] * length;
}
}
}
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