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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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16
pico/pico_cmn.c
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@ -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))
PicoSyncZ80(Pico.t.m68c_aim);
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)