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Genesis-Plus-GX/source/vdp.c

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/***************************************************************************************
* Genesis Plus
* Video Display Processor (memory handlers)
*
* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003 Charles Mac Donald (original code)
* Eke-Eke (2007,2008,2009), additional code & fixes for the GCN/Wii port
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
****************************************************************************************/
#include "shared.h"
#include "hvc.h"
/* Pack and unpack CRAM data */
#define PACK_CRAM(d) ((((d)&0xE00)>>9)|(((d)&0x0E0)>>2)|(((d)&0x00E)<<5))
#define UNPACK_CRAM(d) ((((d)&0x1C0)>>5)|((d)&0x038)<<2|(((d)&0x007)<<9))
/* Mark a pattern as dirty */
#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) & 0x07)); \
}
/* VDP context */
uint8 sat[0x400]; /* Internal copy of sprite attribute table */
uint8 vram[0x10000]; /* Video RAM (64Kx8) */
uint8 cram[0x80]; /* On-chip color RAM (64x9) */
uint8 vsram[0x80]; /* On-chip vertical scroll RAM (40x11) */
uint8 reg[0x20]; /* Internal VDP registers (23x8) */
uint16 addr; /* Address register */
uint16 addr_latch; /* Latched A15, A14 of address */
uint8 code; /* Code register */
uint8 pending; /* Pending write flag */
uint16 status; /* VDP status flags */
uint8 dmafill; /* next VDP Write is DMA Fill */
uint8 hint_pending; /* 0= Line interrupt is pending */
uint8 vint_pending; /* 1= Frame interrupt is pending */
uint8 irq_status; /* 68K IRQ status */
/* 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 bg_pattern_cache[0x80000]; /* Cached and flipped patterns */
uint8 playfield_shift; /* Width of planes A, B (in bits) */
uint8 playfield_col_mask; /* Vertical scroll mask */
uint16 playfield_row_mask; /* Horizontal scroll mask */
uint16 v_counter; /* VDP scanline counter */
uint32 hvc_latch; /* latched HVCounter (INT2) */
uint32 dma_length; /* Current DMA remaining bytes */
int32 fifo_write_cnt; /* VDP writes fifo count */
uint32 fifo_lastwrite; /* last VDP write cycle */
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) */
uint16 lines_per_frame; /* PAL: 313 lines, NTSC: 262 lines */
/* Tables that define the playfield layout */
static const uint8 shift_table[] = { 6, 7, 0, 8 }; /* fixes Window Bug test program */
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 uint16 sat_base_mask; /* Base bits of SAT */
static uint16 sat_addr_mask; /* Index bits of SAT */
static uint32 dma_endCycles; /* 68k cycles to DMA end */
static uint32 dma_type; /* DMA mode */
static uint32 fifo_latency; /* CPU access latency */
/* DMA Timings
According to the manual, here's a table that describes the transfer
rates of each of the three DMA types:
DMA Mode Width Display Transfer Count
-----------------------------------------------------
68K > VDP 32-cell Active 16
Blanking 167
40-cell Active 18
Blanking 205
VRAM Fill 32-cell Active 15
Blanking 166
40-cell Active 17
Blanking 204
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.
*/
static const uint8 dma_rates[16] = {
8, 83, 9, 102, /* 68K to VRAM (1 word = 2 bytes) */
16, 167, 18, 205, /* 68K to CRAM or VSRAM */
15, 166, 17, 204, /* DMA fill */
8, 83, 9, 102, /* DMA Copy */
};
/*--------------------------------------------------------------------------*/
/* Functions prototype */
/*--------------------------------------------------------------------------*/
static void fifo_update(unsigned int cycles);
static void data_w(unsigned int data);
static void reg_w(unsigned int r, unsigned int d);
static void dma_copy(void);
static void dma_vbus (void);
static void dma_fill(unsigned int data);
/*--------------------------------------------------------------------------*/
/* Init, reset, shutdown functions */
/*--------------------------------------------------------------------------*/
void vdp_init(void)
{
/* PAL/NTSC timings */
lines_per_frame = vdp_pal ? 313: 262;
}
void vdp_reset(void)
{
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;
hint_pending = 0;
vint_pending = 0;
irq_status = 0;
hvc_latch = 0;
v_counter = 0;
dmafill = 0;
dma_length = 0;
dma_endCycles = 0;
dma_type = 0;
odd_frame = 0;
im2_flag = 0;
interlaced = 0;
fifo_write_cnt = 0;
fifo_lastwrite = 0;
fifo_latency = 190;
status = vdp_pal | 0x0200; /* FIFO empty */
ntab = 0;
ntbb = 0;
ntwb = 0;
satb = 0;
hscb = 0;
sat_base_mask = 0xFE00;
sat_addr_mask = 0x01FF;
playfield_shift = 6;
playfield_col_mask = 0x0F;
playfield_row_mask = 0x0FF;
bg_list_index = 0;
memset ((char *) bg_name_dirty, 0, sizeof (bg_name_dirty));
memset ((char *) bg_name_list, 0, sizeof (bg_name_list));
memset ((char *) bg_pattern_cache, 0, sizeof (bg_pattern_cache));
playfield_shift = 6;
playfield_col_mask = 0x0F;
playfield_row_mask = 0x0FF;
/* reset HVC tables */
vctab = vdp_pal ? vc_pal_224 : vc_ntsc_224;
hctab = cycle2hc32;
/* reset display area */
bitmap.viewport.w = 256;
bitmap.viewport.h = 224;
bitmap.viewport.ow = 256;
bitmap.viewport.oh = 224;
/* reset overscan area */
bitmap.viewport.x = 0;
bitmap.viewport.y = 0;
if (config.overscan & 1)
bitmap.viewport.y = vdp_pal ? 32 : 8;
if (config.overscan & 2)
bitmap.viewport.x = 12;
/* initialize registers if OS ROM is not used */
if (config.tmss == 1)
{
reg_w(0 , 0x04); /* Palette bit set */
reg_w(1 , 0x04); /* Mode 5 enabled */
reg_w(10, 0xff); /* HINT disabled */
reg_w(12, 0x81); /* H40 mode */
reg_w(15, 0x02); /* auto increment */
}
}
void vdp_shutdown(void)
{}
void vdp_restore(uint8 *vdp_regs)
{
int i;
for (i=0;i<0x20;i++)
{
reg_w(i, vdp_regs[i]);
}
/* reinitialize HVC tables */
vctab = (vdp_pal) ? ((reg[1] & 8) ? vc_pal_240 : vc_pal_224) : vc_ntsc_224;
hctab = (reg[12] & 1) ? cycle2hc40 : cycle2hc32;
/* restore FIFO timings */
fifo_latency = (reg[12] & 1) ? 190 : 214;
if ((code & 0x0F) == 0x01)
fifo_latency = fifo_latency * 2;
/* remake cache */
for (i=0;i<0x800;i++)
{
bg_name_list[i]=i;
bg_name_dirty[i]=0xFF;
}
bg_list_index=0x800;
/* reinitialize palette */
color_update(0x00, *(uint16 *)&cram[border << 1]);
for(i = 1; i < 0x40; i += 1)
color_update(i, *(uint16 *)&cram[i << 1]);
}
/*--------------------------------------------------------------------------*/
/* DMA update */
/*--------------------------------------------------------------------------*/
void vdp_update_dma()
{
int dma_cycles = 0;
/* update DMA timings */
unsigned int index = dma_type;
if ((status & 8) || !(reg[1] & 0x40)) index++;
if (reg[12] & 1) index += 2;
/* DMA transfer rate (bytes per line) */
unsigned int rate = dma_rates[index];
/* 68k cycles left */
int left_cycles = (mcycles_vdp + MCYCLES_PER_LINE) - mcycles_68k;
if (left_cycles < 0) left_cycles = 0;
/* DMA bytes left */
unsigned int dma_bytes = (left_cycles * rate) / MCYCLES_PER_LINE;
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] DMA type %d (%d access/line)-> %d access (%d remaining) (%x)\n", v_counter, mcycles_68k/MCYCLES_PER_LINE, mcycles_68k, mcycles_68k%MCYCLES_PER_LINE,dma_type/4, rate, dma_length, dma_bytes, m68k_get_reg (NULL, M68K_REG_PC));
#endif
/* determinate DMA length in CPU cycles */
if (dma_length < dma_bytes)
{
/* DMA will be finished during this line */
dma_cycles = (dma_length * MCYCLES_PER_LINE) / rate;
dma_length = 0;
}
else
{
/* DMA can not be finished until next scanline */
dma_cycles = left_cycles;
dma_length -= dma_bytes;
}
/* update 68k cycles counter */
if (dma_type < 8)
{
/* 68K to VRAM, CRAM, VSRAM */
/* 68K is frozen during DMA operation */
mcycles_68k += dma_cycles;
#ifdef LOGVDP
error("-->CPU frozen for %d cycles\n", dma_cycles);
#endif
}
else
{
/* VRAM Fill or VRAM Copy */
/* set DMA end cyles count */
dma_endCycles = mcycles_68k + dma_cycles;
#ifdef LOGVDP
error("-->DMA ends in %d cycles\n", dma_cycles);
#endif
/* set DMA Busy flag */
status |= 0x0002;
}
}
/*--------------------------------------------------------------------------*/
/* VDP Ports handler */
/*--------------------------------------------------------------------------*/
void vdp_ctrl_w(unsigned int data)
{
if (pending == 0)
{
if ((data & 0xC000) == 0x8000)
{
/* VDP register write */
reg_w((data >> 8) & 0x1F,data & 0xFF);
}
else
{
/* Set pending flag */
pending = 1;
}
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));
/* DMA operation */
if ((code & 0x20) && (reg[1] & 0x10))
{
switch (reg[23] >> 6)
{
case 2: /* VRAM fill */
dmafill = 1;
break;
case 3: /* VRAM copy */
dma_copy();
break;
default: /* V bus to VDP DMA */
dma_vbus();
break;
}
}
}
/*
FIFO emulation (Chaos Engine/Soldier of Fortune, Double Clutch, Sol Deace)
--------------------------------------------------------------------------
CPU access per line is limited during active display:
H32: 16 access --> 3420/16 = ~214 Mcycles between access
H40: 18 access --> 3420/18 = ~190 Mcycles between access
This is an approximation, on real hardware, the delay between access is
more likely 16 pixels (128 or 160 Mcycles) with no access allowed during
HBLANK (~860 Mcycles), H40 mode being probably a little more restricted.
Each VRAM access is byte wide, so one VRAM write (word) need twice cycles.
*/
fifo_latency = (reg[12] & 1) ? 190 : 214;
if ((code & 0x0F) == 0x01)
fifo_latency = fifo_latency * 2;
}
/*
* Return VDP status
*
* Bits are
* 0 0:1 ntsc:pal
* 1 DMA Busy
* 2 During HBlank
* 3 During VBlank
* 4 0:1 even:odd field (interlaced modes)
* 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_ctrl_r(unsigned int cycles)
{
/* update FIFO flags */
fifo_update(cycles);
/* update DMA Busy flag */
if ((status & 2) && !dma_length && (cycles >= dma_endCycles))
status &= 0xFFFD;
unsigned int temp = status;
/* display OFF: VBLANK flag is set */
if (!(reg[1] & 0x40))
temp |= 0x08;
/* HBLANK flag (Sonic 3 and Sonic 2 "VS Modes", Lemmings 2, Mega Turrican, V.R Troopers, Gouketsuji Ichizoku, ...) */
if ((cycles % MCYCLES_PER_LINE) < 588)
temp |= 0x04;
/* clear pending flag */
pending = 0;
/* clear SPR/SCOL flags */
status &= 0xFF9F;
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] VDP status read -> 0x%x (%x)\n", v_counter, cycles/MCYCLES_PER_LINE, cycles, cycles%MCYCLES_PER_LINE, temp, m68k_get_reg (NULL, M68K_REG_PC));
#endif
return (temp);
}
unsigned int vdp_hvc_r(unsigned int cycles)
{
/* HVC is frozen (Lightgun games, Sunset Riders) */
if (hvc_latch) return (hvc_latch & 0xffff);
/* Horizontal Counter (Striker, Mickey Mania, Skitchin, Road Rash I,II,III, Sonic 3D Blast...) */
uint8 hc = hctab[cycles%MCYCLES_PER_LINE];
/* Vertical Counter */
uint8 vc = vctab[v_counter];
/* interlace mode 2 (Sonic the Hedgehog 2, Combat Cars) */
if (im2_flag)
vc = (vc << 1) | ((vc >> 7) & 1);
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] VDP HVC Read -> 0x%04x (%x)\n", v_counter, cycles/MCYCLES_PER_LINE, cycles, cycles%MCYCLES_PER_LINE,(vc << 8) | hc, m68k_get_reg (NULL, M68K_REG_PC));
#endif
return ((vc << 8) | hc);
}
void vdp_test_w(unsigned int data)
{
#ifdef LOGERROR
error("Unused VDP Write 0x%x (%08x)\n", data, m68k_get_reg (NULL, M68K_REG_PC));
#endif
}
void vdp_data_w(unsigned int data)
{
/* Clear pending flag */
pending = 0;
if (dmafill)
{
dma_fill(data);
return;
}
/* restricted VDP writes during active display */
if (!(status & 8) && (reg[1] & 0x40))
{
/* update VDP FIFO */
fifo_update(mcycles_68k);
/* increase FIFO word count */
fifo_write_cnt ++;
/* FIFO is not empty anymore */
status &= 0xFDFF;
/* FIFO full ? */
if (fifo_write_cnt >= 4)
{
/* update VDP status flag */
status |= 0x100;
/* CPU is delayed (Chaos Engine, Soldiers of Fortune, Double Clutch) */
if (fifo_write_cnt > 4)
mcycles_68k = fifo_lastwrite + fifo_latency;
}
}
/* write data */
data_w(data);
}
unsigned int vdp_data_r(void)
{
uint16 temp = 0;
/* Clear pending flag */
pending = 0;
switch (code & 0x0F)
{
case 0x00: /* VRAM */
temp = *(uint16 *) & vram[(addr & 0xFFFE)];
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] VRAM 0x%x read -> 0x%x (%x)\n", v_counter, mcycles_68k/MCYCLES_PER_LINE, mcycles_68k, mcycles_68k%MCYCLES_PER_LINE, addr, temp, m68k_get_reg (NULL, M68K_REG_PC));
#endif
break;
case 0x08: /* CRAM */
temp = *(uint16 *) & cram[(addr & 0x7E)];
temp = UNPACK_CRAM (temp);
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] CRAM 0x%x read -> 0x%x (%x)\n", v_counter, mcycles_68k/MCYCLES_PER_LINE, mcycles_68k, mcycles_68k%MCYCLES_PER_LINE, addr, temp, m68k_get_reg (NULL, M68K_REG_PC));
#endif
break;
case 0x04: /* VSRAM */
temp = *(uint16 *) & vsram[(addr & 0x7E)];
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] VSRAM 0x%x read -> 0x%x (%x)\n", v_counter, mcycles_68k/MCYCLES_PER_LINE, mcycles_68k, mcycles_68k%MCYCLES_PER_LINE, addr, temp, m68k_get_reg (NULL, M68K_REG_PC));
#endif
break;
#ifdef LOGVDP
default:
error("[%d(%d)][%d(%d)] Unknown (%d) 0x%x read (%x)\n", v_counter, mcycles_68k/MCYCLES_PER_LINE, mcycles_68k, mcycles_68k%MCYCLES_PER_LINE, code, addr, m68k_get_reg (NULL, M68K_REG_PC));
break;
#endif
}
/* Increment address register */
addr += reg[15];
/* return data */
return (temp);
}
/*--------------------------------------------------------------------------*/
/* VDP Interrupts callback */
/*--------------------------------------------------------------------------*/
int vdp_int_ack_callback(int int_level)
{
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] INT Level %d ack (%x)\n", v_counter, mcycles_68k/MCYCLES_PER_LINE, mcycles_68k, mcycles_68k%MCYCLES_PER_LINE,int_level, m68k_get_reg (NULL, M68K_REG_PC));
#endif
/* VINT triggered ? */
if (irq_status&0x20)
{
vint_pending = 0;
status &= ~0x80; /* clear VINT flag */
#ifdef LOGVDP
error("---> VINT cleared\n");
#endif
/* update IRQ status */
if (hint_pending & reg[0])
{
irq_status = 0x14;
}
else
{
irq_status = 0x00;
m68k_set_irq(0);
}
}
else
{
hint_pending = 0;
#ifdef LOGVDP
error("---> HINT cleared\n");
#endif
/* update IRQ status */
if (vint_pending & reg[1])
{
irq_status = 0x16;
}
else
{
irq_status = 0x00;
m68k_set_irq(0);
}
}
return M68K_INT_ACK_AUTOVECTOR;
}
/*--------------------------------------------------------------------------*/
/* FIFO emulation */
/*--------------------------------------------------------------------------*/
static void fifo_update(unsigned int cycles)
{
if (fifo_write_cnt > 0)
{
/* update FIFO reads */
int fifo_read = ((cycles - fifo_lastwrite) / fifo_latency);
if (fifo_read > 0)
{
fifo_write_cnt -= fifo_read;
/* update VDP status flags */
if (fifo_write_cnt < 4)
{
/* FIFO is not full anymore */
status &= 0xFEFF;
if (fifo_write_cnt <= 0)
{
/* FIFO is empty */
status |= 0x200;
fifo_write_cnt = 0;
}
}
/* update cycle count */
fifo_lastwrite += (fifo_read * fifo_latency);
}
}
}
/*--------------------------------------------------------------------------*/
/* Memory access functions */
/*--------------------------------------------------------------------------*/
static void data_w(unsigned int data)
{
switch (code & 0x0F)
{
case 0x01: /* VRAM */
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] VRAM 0x%x write -> 0x%x (%x)\n", v_counter, mcycles_68k/MCYCLES_PER_LINE, mcycles_68k, mcycles_68k%MCYCLES_PER_LINE, addr, data, m68k_get_reg (NULL, M68K_REG_PC));
#endif
/* Byte-swap data if A0 is set */
if (addr & 1)
data = ((data >> 8) | (data << 8)) & 0xFFFF;
/* Copy SAT data to the internal SAT */
if ((addr & sat_base_mask) == satb)
{
*(uint16 *) &sat[addr & sat_addr_mask & 0xFFFE] = data;
}
/* Only write unique data to VRAM */
if (data != *(uint16 *) &vram[addr & 0xFFFE])
{
/* Write data to VRAM */
*(uint16 *) &vram[addr & 0xFFFE] = data;
/* Update the pattern cache */
int name;
MARK_BG_DIRTY (addr);
}
break;
case 0x03: /* CRAM */
{
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] CRAM 0x%x write -> 0x%x (%x)\n", v_counter, mcycles_68k/MCYCLES_PER_LINE, mcycles_68k, mcycles_68k%MCYCLES_PER_LINE, addr, data, m68k_get_reg (NULL, M68K_REG_PC));
#endif
uint16 *p = (uint16 *) &cram[(addr & 0x7E)];
data = PACK_CRAM (data);
if (data != *p)
{
int index = (addr >> 1) & 0x3F;
*p = data;
/* update color palette */
/* color entry 0 of each palette is never displayed (transparent pixel) */
if (index & 0x0F)
color_update(index, data);
/* update background color */
if (border == index)
color_update (0x00, data);
/* CRAM modified during HBLANK (Striker, Zero the Kamikaze, etc) */
if (!(status & 8) && (reg[1]& 0x40) && (mcycles_68k <= (mcycles_vdp + 860)))
{
/* remap current line */
remap_buffer(v_counter);
#ifdef LOGVDP
error("Line remapped\n");
#endif
}
#ifdef LOGVDP
else error("Line NOT remapped\n");
#endif
}
break;
}
case 0x05: /* VSRAM */
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] VSRAM 0x%x write -> 0x%x (%x)\n", v_counter, mcycles_68k/MCYCLES_PER_LINE, mcycles_68k, mcycles_68k%MCYCLES_PER_LINE, addr, data, m68k_get_reg (NULL, M68K_REG_PC));
#endif
*(uint16 *) &vsram[(addr & 0x7E)] = data;
break;
#ifdef LOGVDP
default:
error("[%d(%d)][%d(%d)] Unknown (%d) 0x%x write -> 0x%x (%x)\n", v_counter, mcycles_68k/MCYCLES_PER_LINE, mcycles_68k, mcycles_68k%MCYCLES_PER_LINE, code, addr, data, m68k_get_reg (NULL, M68K_REG_PC));
break;
#endif
}
/* Increment address register */
addr += reg[15];
}
static void reg_w(unsigned int r, unsigned int d)
{
#ifdef LOGVDP
error("[%d(%d)][%d(%d)] VDP register %d write -> 0x%x (%x)\n", v_counter, mcycles_68k/MCYCLES_PER_LINE, mcycles_68k, mcycles_68k%MCYCLES_PER_LINE, r, d, m68k_get_reg (NULL, M68K_REG_PC));
#endif
/* Mode 4 (SMS mode) is enabled
According to official doc, VDP registers #11 to #23 can not be written unless bit2 in register #1 is set
Fix Captain Planet & Avengers (Alt version), Bass Master Classic Pro Edition (they incidentally activate Mode 4)
*/
if (!(reg[1] & 4) && (r > 10))
return;
switch(r)
{
case 0: /* CTRL #1 */
/* look for changed bits */
r = d ^ reg[r];
reg[0] = d;
/* Line Interrupt */
if ((r & 0x10) && hint_pending)
{
/* update IRQ status */
irq_status = 0x50;
if (vint_pending & reg[1])
irq_status |= 0x26;
else if (d & 0x10)
irq_status |= 4;
}
/* Palette bit */
if (r & 0x04)
{
/* Update colors */
int i;
color_update (0x00, *(uint16 *) & cram[border << 1]);
for (i = 1; i < 0x40; i += 1)
color_update (i, *(uint16 *) & cram[i << 1]);
}
/* HVC latch bit */
if (r & 0x02)
{
if (reg[0] & 2) /* latch current HVC */
hvc_latch = 0x10000 | (vctab[v_counter] << 8) | hctab[mcycles_68k%MCYCLES_PER_LINE];
else /* free-running HVC */
hvc_latch = 0;
}
break;
case 1: /* CTRL #2 */
/* look for changed bits */
r = d ^ reg[r];
reg[1] = d;
/* Frame Interrupt */
if ((r & 0x20) && vint_pending)
{
/* update IRQ status */
irq_status = 0x50;
if (d & 0x20)
irq_status |= 0x26;
else if (hint_pending & reg[0])
irq_status |= 4;
}
/* See if the viewport height has actually been changed */
if (r & 0x08)
{
/* Update V Counter table */
if (vdp_pal)
vctab = (d & 8) ? vc_pal_240 : vc_pal_224;
/* Update viewport */
if (status & 8)
{
/* changes should be applied on next frame */
bitmap.viewport.changed |= 2;
}
else
{
/* Update active display */
if (d & 8)
{
bitmap.viewport.h = 240;
bitmap.viewport.y = (config.overscan & 1) ? (vdp_pal ? 24 : 0) : 0;
}
else
{
bitmap.viewport.h = 224;
bitmap.viewport.y = (config.overscan & 1) ? (vdp_pal ? 32 : 8) : 0;
}
}
}
/* Display status modified during active display (Legend of Galahad, Lemmings 2, */
/* Formula One Championship, Nigel Mansell's World Championship Racing, ...) */
if ((r & 0x40) && !(status & 8))
{
int offset = mcycles_68k - mcycles_vdp - 860;
if (offset <= 0)
{
/* redraw entire line */
render_line(v_counter);
#ifdef LOGVDP
error("Line redrawn (%d sprites) \n",object_count[object_which^1]);
#endif
/* If display is was disabled during HBLANK (Mickey Mania 3D level), sprite processing is limited */
/* Below values have been deducted from testing on this game, accurate emulation would require */
/* to know exact sprite (pre)processing timings. Hopefully, they don't seem to break any other */
/* games, so they might not be so much inaccurate. */
if (d & 0x40)
{
parse_satb(0x81 + v_counter);
if ((object_count[object_which^1] > 5) && (mcycles_68k % MCYCLES_PER_LINE >= 360))
object_count[object_which^1] = 5;
}
}
else
{
/* pixel offset */
if (reg[12] & 1) offset = offset / 8;
else offset = (offset / 10) + 16;
#ifdef LOGVDP
error("Line %d redrawn from pixel %d\n",v_counter,offset);
#endif
/* line is partially blanked */
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);
}
}
}
}
break;
case 2: /* NTAB */
reg[2] = d;
ntab = (d << 10) & 0xE000;
break;
case 3: /* NTWB */
reg[3] = d;
if (reg[12] & 1)
ntwb = (d << 10) & 0xF000;
else
ntwb = (d << 10) & 0xF800;
break;
case 4: /* NTBB */
reg[4] = d;
ntbb = (d << 13) & 0xE000;
break;
case 5: /* SATB */
reg[5] = d;
satb = (d << 9) & sat_base_mask;
break;
case 7:
reg[7] = d;
/* See if the background color has actually changed */
d &= 0x3F;
if (d != border)
{
/* update background color */
border = d;
color_update(0x00, *(uint16 *)&cram[(d << 1)]);
/* background color modified during Horizontal Blanking (Road Rash 1,2,3)*/
if (!(status & 8) && (mcycles_68k <= (mcycles_vdp + 860)))
{
/* remap entire line */
remap_buffer(v_counter);
#ifdef LOGVDP
error("Line remapped\n");
#endif
}
#ifdef LOGVDP
else error("Line NOT remapped\n");
#endif
}
break;
case 12:
/* look for changed bits */
r = d ^ reg[r];
reg[12] = d;
/* See if the viewport width has actually been changed */
if (r & 0x01)
{
if (d & 1)
{
/* 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 fifo timings */
fifo_latency = 190;
}
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 fifo timings */
fifo_latency = 214;
}
if ((code & 0x0F) == 0x01)
fifo_latency = fifo_latency * 2;
/* Update clipping */
window_clip();
/* display width changed during HBLANK (Bugs Bunny Double Trouble) */
if (!(status & 8))
{
if (mcycles_68k <= (mcycles_vdp + 860))
{
/* redraw entire line */
render_line(v_counter);
}
}
/* changes should be applied on next frame */
bitmap.viewport.changed |= 2;
}
/* Interlaced modes */
if (r & 0x06)
{
/* changes should be applied on next frame */
bitmap.viewport.changed |= 2;
}
/* See if the S/TE mode bit has changed */
if (r & 0x08)
{
/* Update colors */
int i;
color_update (0x00, *(uint16 *) & cram[border << 1]);
for (i = 1; i < 0x40; i += 1)
color_update (i, *(uint16 *) & cram[i << 1]);
}
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 clipping */
reg[17] = d;
window_clip();
break;
default:
reg[r] = d;
break;
}
}
/*--------------------------------------------------------------------------*/
/* DMA Operations */
/*--------------------------------------------------------------------------*/
/* DMA Copy
Read byte from VRAM (source), write to VRAM (addr),
bump source and add r15 to addr.
- see how source addr is affected
(can it make high source byte inc?)
*/
static void dma_copy(void)
{
int name;
unsigned int length = (reg[20] << 8 | reg[19]) & 0xFFFF;
unsigned int source = (reg[22] << 8 | reg[21]) & 0xFFFF;
if (!length)
length = 0x10000;
dma_type = 12;
dma_length = length;
vdp_update_dma();
/* proceed DMA */
do
{
vram[addr] = vram[source];
MARK_BG_DIRTY(addr);
source = (source + 1) & 0xFFFF;
addr += reg[15];
} while (--length);
/* update length & source address registers */
reg[19] = length & 0xFF;
reg[20] = (length >> 8) & 0xFF;
reg[21] = source & 0xFF; /* not sure */
reg[22] = (source >> 8) & 0xFF;
}
/* 68K Copy to VRAM, VSRAM or CRAM */
static void dma_vbus (void)
{
unsigned int source = ((reg[23] & 0x7F) << 17 | reg[22] << 9 | reg[21] << 1) & 0xFFFFFE;
unsigned int base = source;
unsigned int length = (reg[20] << 8 | reg[19]) & 0xFFFF;
uint16 temp;
if (!length)
length = 0x10000;
/* DMA timings */
dma_type = (code & 0x06) ? 4 : 0;
dma_length = length;
vdp_update_dma();
/* DMA source */
if ((source >> 17) == 0x50)
{
/* Z80 & I/O area */
do
{
/* Return $FFFF only when the Z80 isn't hogging the Z-bus.
(e.g. Z80 isn't reset and 68000 has the bus) */
if (source <= 0xa0ffff)
temp = ((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)
{
temp = io_read((source >> 1) & 0x0f);
temp = (temp << 8 | temp);
}
/* All remaining locations access work RAM */
else
temp = *(uint16 *)(work_ram + (source & 0xffff));
source += 2;
source = ((base & 0xFE0000) | (source & 0x1FFFF));
data_w(temp);
}
while (--length);
}
else
{
/* SVP latency */
if (svp && (source < 0x400000))
{
source = (source - 2);
}
/* ROM & RAM */
do
{
temp = *(uint16 *)(m68k_memory_map[source>>16].base + (source & 0xffff));
source += 2;
source = ((base & 0xFE0000) | (source & 0x1FFFF));
data_w(temp);
}
while (--length);
}
/* update length & source address registers */
reg[19] = length & 0xFF;
reg[20] = (length >> 8) & 0xFF;
reg[21] = (source >> 1) & 0xFF;
reg[22] = (source >> 9) & 0xFF;
reg[23] = (reg[23] & 0x80) | ((source >> 17) & 0x7F);
}
/* VRAM FILL */
static void dma_fill(unsigned int data)
{
int name;
unsigned int length = (reg[20] << 8 | reg[19]) & 0xFFFF;
if (!length)
length = 0x10000;
/* DMA timings */
dma_type = 8;
dma_length = length;
vdp_update_dma();
/* proceed DMA */
data_w(data);
/* write MSB */
data = (data >> 8) & 0xff;
/* intercept SAT writes */
if ((addr & sat_base_mask) == satb)
{
do
{
/* update internal SAT copy */
WRITE_BYTE(sat, (addr & sat_addr_mask)^1, data);
WRITE_BYTE(vram, addr^1, data);
MARK_BG_DIRTY (addr);
addr += reg[15];
}
while (--length);
}
else
{
do
{
WRITE_BYTE(vram, addr^1, data);
MARK_BG_DIRTY (addr);
addr += reg[15];
}
while (--length);
}
/* update length register */
reg[19] = length & 0xFF;
reg[20] = (length >> 8) & 0xFF;
dmafill = 0;
}
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