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core, improve 68K/Z80 timing

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This commit is contained in:
kub 2023-04-24 23:50:06 +02:00
parent ae9a76c90d
commit 133006a9d4
3 changed files with 20 additions and 11 deletions
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13
pico/memory.c
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@ -325,7 +325,7 @@ static NOINLINE u32 port_read(int i)
out = data_reg & ctrl_reg;
// pull-ups: should be 0x7f, but Decap Attack has a bug where it temp.
// disables output before doing TH-low read, so don't emulate it for TH.
// disables output before doing TH-low read, so emulate RC filter for TH.
// Decap Attack reportedly doesn't work on Nomad but works on must
// other MD revisions (different pull-up strength?).
u32 mask = 0x3f;
@ -599,9 +599,10 @@ static u32 PicoRead8_z80(u32 a)
return 0;
}
if ((a & 0x4000) == 0x0000)
if ((a & 0x4000) == 0x0000) {
SekCyclesBurnRun(1);
d = PicoMem.zram[a & 0x1fff];
else if ((a & 0x6000) == 0x4000) // 0x4000-0x5fff
} else if ((a & 0x6000) == 0x4000) // 0x4000-0x5fff
d = ym2612_read_local_68k();
else
elprintf(EL_UIO|EL_ANOMALY, "68k bad read [%06x] @%06x", a, SekPc);
@ -623,6 +624,7 @@ static void PicoWrite8_z80(u32 a, u32 d)
}
if ((a & 0x4000) == 0x0000) { // z80 RAM
SekCyclesBurnRun(1);
PicoMem.zram[a & 0x1fff] = (u8)d;
return;
}
@ -1269,9 +1271,10 @@ void PicoWrite16_32x(u32 a, u32 d) {}
static unsigned char z80_md_vdp_read(unsigned short a)
{
z80_subCLeft(2);
if ((a & 0xff00) == 0x7f00) {
z80_subCLeft(3);
Pico.t.z80_buscycles += 7;
if ((a & 0x00f0) == 0x0000) {
switch (a & 0x0d)
{
case 0x00: return PicoVideoRead8DataH(1);

2
pico/pico.c
View file

@ -187,7 +187,7 @@ int PicoReset(void)
PsndReset(); // pal must be known here
// create an empty "dma" to cause 68k exec start at random frame location
Pico.t.m68c_line_start = Pico.t.m68c_cnt;
Pico.t.m68c_line_start = Pico.t.m68c_aim;
PicoVideoFIFOWrite(rand() & 0x1fff, 0, 0, PVS_CPURD);
SekFinishIdleDet();

14
pico/pico_cmn.c
View file

@ -47,9 +47,9 @@ static void SekSyncM68k(void)
while ((cyc_do = Pico.t.m68c_aim - Pico.t.m68c_cnt) > 0) {
// the Z80 CPU is stealing some bus cycles from the 68K main CPU when
// accessing the 68K RAM or ROM. Account for these by shortening the time
// accessing the main bus. Account for these by shortening the time
// the 68K CPU runs.
int z80_buscyc = Pico.t.z80_buscycles;
int z80_buscyc = Pico.t.z80_buscycles >> (~Pico.m.scanline & 1);
if (z80_buscyc <= cyc_do)
SekExecM68k(cyc_do - z80_buscyc);
else
@ -65,8 +65,12 @@ static void SekSyncM68k(void)
static __inline void SekRunM68k(int cyc)
{
// refresh slowdown handling, 2 cycles every 128 - make this 1 every 64
// NB must be quite accurate, so handle fractions as well (c/f OutRunners)
static int refresh;
Pico.t.m68c_cnt += (cyc + refresh) >> 6;
refresh = (cyc + refresh) & 0x3f;
Pico.t.m68c_aim += cyc;
Pico.t.m68c_cnt += cyc >> 6; // refresh slowdowns
SekSyncM68k();
}
@ -101,8 +105,10 @@ static void do_timing_hacks_end(struct PicoVideo *pv)
PicoVideoFIFOSync(CYCLES_M68K_LINE);
// need rather tight Z80 sync for emulation of main bus cycle stealing
if (Pico.m.z80Run && !Pico.m.z80_reset && (PicoIn.opt&POPT_EN_Z80) && (Pico.m.scanline&1))
if (Pico.m.scanline&1) {
if (Pico.m.z80Run && !Pico.m.z80_reset && (PicoIn.opt&POPT_EN_Z80))
PicoSyncZ80(Pico.t.m68c_aim);
}
}
static void do_timing_hacks_start(struct PicoVideo *pv)