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emulator timing fixes, VDP DMA fixes, improved DAC audio

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This commit is contained in:
kub 2020-01-14 23:00:44 +01:00
parent b9bc876c9c
commit 43e1401008
10 changed files with 118 additions and 98 deletions
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33
pico/pico.c
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@ -224,40 +224,45 @@ void PicoLoopPrepare(void)
// this table is wrong and should be removed
// keeping it for now to compensate wrong timing elswhere, mainly for Outrunners
static const int dma_timings[] = {
83, 166, 83, 83, // vblank: 32cell: dma2vram dma2[vs|c]ram vram_fill vram_copy
102, 204, 102, 102, // vblank: 40cell:
8, 16, 8, 8, // active: 32cell:
17, 18, 9, 9 // ...
static const int dma_timings[] = { // Q16
// dma2vram dma2[vs|c]ram vram_fill vram_copy
// VRAM has half the width of VSRAM/CRAM, thus half the performance
( 83<<16)/488, (166<<16)/488, (165<<16)/488, ( 83<<16)/488, // vblank 32cell
(102<<16)/488, (204<<16)/488, (203<<16)/488, (102<<16)/488, // vblank 40cell
( 8<<16)/488, ( 16<<16)/488, ( 15<<16)/488, ( 8<<16)/488, // active 32cell
( 9<<16)/488, ( 18<<16)/488, ( 17<<16)/488, ( 9<<16)/488 // active 40cell
};
static const int dma_bsycles[] = {
(488<<8)/83, (488<<8)/166, (488<<8)/83, (488<<8)/83,
(488<<8)/102, (488<<8)/204, (488<<8)/102, (488<<8)/102,
(488<<8)/8, (488<<8)/16, (488<<8)/8, (488<<8)/8,
(488<<8)/9, (488<<8)/18, (488<<8)/9, (488<<8)/9
static const int dma_bsycles[] = { // Q16
(488<<16)/83, (488<<16)/166, (488<<16)/165, (488<<16)/83,
(488<<16)/102, (488<<16)/204, (488<<16)/203, (488<<16)/102,
(488<<16)/8, (488<<16)/16, (488<<16)/15, (488<<16)/8,
(488<<16)/9, (488<<16)/18, (488<<16)/17, (488<<16)/9
};
// grossly inaccurate.. FIXME FIXXXMEE
PICO_INTERNAL int CheckDMA(void)
PICO_INTERNAL int CheckDMA(int cycles)
{
int burn = 0, xfers_can, dma_op = Pico.video.reg[0x17]>>6; // see gens for 00 and 01 modes
int xfers = Pico.m.dma_xfers;
int dma_op1;
// safety pin
if (cycles <= 0) return 0;
if(!(dma_op&2)) dma_op = (Pico.video.type==1) ? 0 : 1; // setting dma_timings offset here according to Gens
dma_op1 = dma_op;
if(Pico.video.reg[12] & 1) dma_op |= 4; // 40 cell mode?
if(!(Pico.video.status&8)&&(Pico.video.reg[1]&0x40)) dma_op|=8; // active display?
xfers_can = dma_timings[dma_op];
xfers_can = (dma_timings[dma_op] * cycles + 0xff) >> 16;
if(xfers <= xfers_can)
{
Pico.video.status &= ~SR_DMA;
if (!(dma_op & 2))
burn = xfers * dma_bsycles[dma_op] >> 8; // have to be approximate because can't afford division..
burn = xfers * dma_bsycles[dma_op] >> 16;
Pico.m.dma_xfers = 0;
} else {
if(!(dma_op&2)) burn = 488;
if(!(dma_op&2)) burn = cycles;
Pico.m.dma_xfers -= xfers_can;
}