[Core/VDP] implemented proper FIFO ring-buffer & unused bits behavior on CRAM/VSRAM reads (verified on real hardware)

This commit is contained in:
EkeEke 2013-10-20 23:48:36 +02:00 committed by twinaphex
parent 1b0db486e7
commit 16b00f9368
3 changed files with 90 additions and 37 deletions

View File

@ -51,7 +51,7 @@ int state_load(unsigned char *state)
return 0;
}
/* version check (1.7.1 and above only) */
/* version check (keep compatibility with previous & current state version) */
if ((version[11] < 0x31) || (version[13] < 0x37) || (version[15] < 0x31))
{
return 0;
@ -110,7 +110,7 @@ int state_load(unsigned char *state)
}
/* VDP */
bufferptr += vdp_context_load(&state[bufferptr]);
bufferptr += vdp_context_load(&state[bufferptr], version[15]);
/* SOUND */
bufferptr += sound_context_load(&state[bufferptr]);

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@ -136,7 +136,8 @@ static uint16 dma_src; /* DMA source address */
static uint16 dmafill; /* DMA Fill setup */
static uint32 dma_endCycles; /* 68k cycles to DMA end */
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 buffer */
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 */
@ -231,6 +232,7 @@ void vdp_reset(void)
fifo_write_cnt = 0;
fifo_cycles = 0;
fifo_slots = 0;
fifo_idx = 0;
cached_write = -1;
fifo_byte_access = 1;
@ -312,16 +314,16 @@ void vdp_reset(void)
parse_satb = parse_satb_m4;
}
/* 68k bus access mode (Mode 4 by default) */
/* 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;
/* Z80 bus access mode */
/* default Z80 bus interface */
switch (system_hw)
{
case SYSTEM_SG:
{
/* SG-1000 port access */
/* SG-1000 VDP (TMS99xx) */
vdp_z80_data_w = vdp_z80_data_w_sg;
vdp_z80_data_r = vdp_z80_data_r_m4;
break;
@ -329,7 +331,7 @@ void vdp_reset(void)
case SYSTEM_GG:
{
/* Game Gear port access */
/* Game Gear VDP */
vdp_z80_data_w = vdp_z80_data_w_gg;
vdp_z80_data_r = vdp_z80_data_r_m4;
break;
@ -340,7 +342,7 @@ void vdp_reset(void)
case SYSTEM_SMS2:
case SYSTEM_GGMS:
{
/* Master System port access */
/* 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;
@ -348,7 +350,7 @@ void vdp_reset(void)
default:
{
/* Genesis port access */
/* 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;
@ -361,7 +363,7 @@ void vdp_reset(void)
/* 16k address decoding by default (Magical Kid Wiz) */
vdp_reg_w(1, 0x80, 0);
/* no H-INT on TMS9918 */
/* no H-INT on TMS99xx */
vdp_reg_w(10, 0xFF, 0);
}
@ -418,6 +420,8 @@ int vdp_context_save(uint8 *state)
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(&hint_pending, sizeof(hint_pending));
save_param(&vint_pending, sizeof(vint_pending));
save_param(&dma_length, sizeof(dma_length));
@ -427,7 +431,7 @@ int vdp_context_save(uint8 *state)
return bufferptr;
}
int vdp_context_load(uint8 *state)
int vdp_context_load(uint8 *state, uint8 version)
{
int i, bufferptr = 0;
uint8 temp_reg[0x20];
@ -473,13 +477,29 @@ int vdp_context_load(uint8 *state)
load_param(&code, sizeof(code));
load_param(&pending, sizeof(pending));
load_param(&status, sizeof(status));
/* 1.7.1 state compatibility */
if (version < 0x35)
{
uint16 temp;
load_param(&temp, 2);
dmafill = temp >> 8;
temp &= 0xff;
fifo_idx = 0;
fifo[0] = fifo[1] = fifo[2] = fifo[3] = (temp << 8) | temp;
}
else
{
load_param(&dmafill, sizeof(dmafill));
load_param(&fifo_idx, sizeof(fifo_idx));
load_param(&fifo, sizeof(fifo));
}
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 */
@ -528,7 +548,7 @@ int vdp_context_load(uint8 *state)
/*--------------------------------------------------------------------------*/
/* DMA update function */
/* DMA update function (Mega Drive VDP only) */
/*--------------------------------------------------------------------------*/
void vdp_dma_update(unsigned int cycles)
@ -1097,7 +1117,7 @@ void vdp_sms_ctrl_w(unsigned int data)
}
}
/* TMS9918 (SG-1000) VDP control port specific */
/* SG-1000 VDP (TMS99xx) control port specific */
void vdp_tms_ctrl_w(unsigned int data)
{
if(pending == 0)
@ -2140,7 +2160,13 @@ static void vdp_fifo_update(unsigned int cycles)
static void vdp_bus_w(unsigned int data)
{
/* Check destination code */
/* 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 */
@ -2260,7 +2286,7 @@ static void vdp_bus_w(unsigned int data)
/*--------------------------------------------------------------------------*/
/* 68k data port access functions (Genesis mode) */
/* 68k bus interface (Mega Drive VDP only) */
/*--------------------------------------------------------------------------*/
static void vdp_68k_data_w_m4(unsigned int data)
@ -2434,11 +2460,12 @@ static unsigned int vdp_68k_data_r_m5(void)
/* Clear pending flag */
pending = 0;
switch (code & 0x0F)
/* Check destination code (CD0-CD3) & CD4 */
switch (code & 0x1F)
{
case 0x00: /* VRAM */
case 0x00:
{
/* Read data */
/* read two bytes from VRAM */
data = *(uint16 *)&vram[addr & 0xFFFE];
#ifdef LOGVDP
@ -2447,10 +2474,23 @@ static unsigned int vdp_68k_data_r_m5(void)
break;
}
case 0x04: /* VSRAM */
case 0x04:
{
/* Read data */
data = *(uint16 *)&vsram[addr & 0x7E];
/* 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, m68k.cycles/MCYCLES_PER_LINE-1, m68k.cycles, m68k.cycles%MCYCLES_PER_LINE, addr, data, m68k_get_reg(M68K_REG_PC));
@ -2458,24 +2498,30 @@ static unsigned int vdp_68k_data_r_m5(void)
break;
}
case 0x08: /* CRAM */
case 0x08:
{
/* Read data */
/* 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, m68k.cycles/MCYCLES_PER_LINE-1, m68k.cycles, m68k.cycles%MCYCLES_PER_LINE, addr, data, m68k_get_reg(M68K_REG_PC));
#endif
break;
}
case 0x0c: /* undocumented 8-bit VRAM read (cf. http://gendev.spritesmind.net/forum/viewtopic.php?t=790) */
case 0x0c: /* undocumented 8-bit VRAM read */
{
/* Read data (MSB forced to zero) */
data = *(uint16 *)&vram[addr & 0xFFFE] & 0xff;
/* 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, m68k.cycles/MCYCLES_PER_LINE-1, m68k.cycles, m68k.cycles%MCYCLES_PER_LINE, addr, data, m68k_get_reg(M68K_REG_PC));
@ -2485,7 +2531,7 @@ static unsigned int vdp_68k_data_r_m5(void)
default:
{
/* Invalid code value */
/* 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, m68k.cycles/MCYCLES_PER_LINE-1, m68k.cycles, m68k.cycles%MCYCLES_PER_LINE, code, addr, m68k_get_reg(M68K_REG_PC));
#endif
@ -2502,7 +2548,7 @@ static unsigned int vdp_68k_data_r_m5(void)
/*--------------------------------------------------------------------------*/
/* Z80 data port access functions (Master System compatibility mode) */
/* Z80 bus interface (Mega Drive VDP in Master System compatibility mode) */
/*--------------------------------------------------------------------------*/
static void vdp_z80_data_w_m4(unsigned int data)
@ -2562,7 +2608,11 @@ static void vdp_z80_data_w_m5(unsigned int data)
/* Clear pending flag */
pending = 0;
/* Check destination code */
/* 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 */
@ -2690,7 +2740,8 @@ static unsigned int vdp_z80_data_r_m5(void)
/* Clear pending flag */
pending = 0;
switch (code & 0x0F)
/* Check destination code (CD0-CD3) & CD4 */
switch (code & 0x1F)
{
case 0x00: /* VRAM */
{
@ -2734,7 +2785,7 @@ static unsigned int vdp_z80_data_r_m5(void)
/*-----------------------------------------------------------------------------*/
/* VDP specific data port access functions (Master System, Game Gear, SG-1000) */
/* Z80 bus interface (Master System, Game Gear & SG-1000 VDP) */
/*-----------------------------------------------------------------------------*/
static void vdp_z80_data_w_ms(unsigned int data)
@ -2746,10 +2797,11 @@ static void vdp_z80_data_w_ms(unsigned int data)
{
int index;
/* check if we are already on next line */
/* Check if we are already on next line */
int line = (lines_per_frame + (Z80.cycles / MCYCLES_PER_LINE) - 1) % lines_per_frame;
if ((line > v_counter) && (line < bitmap.viewport.h) && !(work_ram[0x1ffb] & cart.special))
{
/* Render next line */
v_counter = line;
render_line(line);
}
@ -2813,10 +2865,11 @@ static void vdp_z80_data_w_gg(unsigned int data)
{
int index;
/* check if we are already on next line*/
/* Check if we are already on next line*/
int line = (lines_per_frame + (Z80.cycles / MCYCLES_PER_LINE) - 1) % lines_per_frame;
if ((line > v_counter) && (line < bitmap.viewport.h) && !(work_ram[0x1ffb] & cart.special))
{
/* Render next line */
v_counter = line;
render_line(line);
}
@ -2907,7 +2960,7 @@ static void vdp_z80_data_w_sg(unsigned int data)
}
/*--------------------------------------------------------------------------*/
/* DMA operations */
/* DMA operations (Mega Drive VDP only) */
/*--------------------------------------------------------------------------*/
/* DMA from 68K bus: $000000-$7FFFFF (external area) */

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@ -90,7 +90,7 @@ extern unsigned int (*vdp_z80_data_r)(void);
extern void vdp_init(void);
extern void vdp_reset(void);
extern int vdp_context_save(uint8 *state);
extern int vdp_context_load(uint8 *state);
extern int vdp_context_load(uint8 *state, uint8 version);
extern void vdp_dma_update(unsigned int cycles);
extern void vdp_68k_ctrl_w(unsigned int data);
extern void vdp_z80_ctrl_w(unsigned int data);