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md, improve z80/68k synchronization

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kub 2023-06-22 22:12:50 +00:02
parent f3876af7f9
commit e0c4dac19c
2 changed files with 20 additions and 17 deletions
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32
pico/memory.c
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@ -1334,12 +1334,22 @@ void PicoWrite16_32x(u32 a, u32 d) {}
// -----------------------------------------------------------------
// z80 memhandlers
static void access_68k_bus(int delay) // bus delay as Q8
{
// 68k bus access delay for z80. The fractional part needs to be accumulated
// until an additional cycle is full. That is then added to the integer part.
Pico.t.z80_busdelay = (delay&0xff) + (Pico.t.z80_busdelay&0xff); // accumulate
z80_subCLeft((delay>>8) + (Pico.t.z80_busdelay>>8));
// don't use SekCyclesBurn(7) here since the Z80 doesn't run in cycle lock to
// the 68K. Count the stolen cycles to be accounted later in the 68k CPU runs
Pico.t.z80_buscycles += 7;
}
static unsigned char z80_md_vdp_read(unsigned short a)
{
if ((a & 0xff00) == 0x7f00) {
static int f; f = (f&0xff) + 0x8c; // 0.6
z80_subCLeft(2+(f>>8)); // 3.3 per kabuto, but notaz' test implies 2.6 ?!?
Pico.t.z80_buscycles += 7;
// 68k bus access delay=3.3 per kabuto, for notaz picotest 2.4<=delay<2.55?
access_68k_bus(0x280); // Q8, picotest: 0x266(>=2.4) - 0x28b(<2.55)
switch (a & 0x0d)
{
@ -1363,12 +1373,8 @@ static unsigned char z80_md_bank_read(unsigned short a)
unsigned int addr68k;
unsigned char ret;
// account for 68K bus access on both CPUs.
static int f; f = (f&0xff) + 0x4c; // 0.3
z80_subCLeft(3+(f>>8)); // 3.3 per kabuto
// don't use SekCyclesBurn(7) here since the Z80 doesn't run in cycle lock to
// the 68K. Count the stolen cycles to be accounted later in the 68k CPU runs
Pico.t.z80_buscycles += 7;
// 68k bus access delay=3.3 per kabuto, but for notaz picotest 3.0<delay<3.3
access_68k_bus(0x340); // // Q8, picotest: 0x301(>3.0)-0x34c(<3.3)
addr68k = Pico.m.z80_bank68k << 15;
addr68k |= a & 0x7fff;
@ -1409,12 +1415,8 @@ static void z80_md_bank_write(unsigned int a, unsigned char data)
{
unsigned int addr68k;
// account for 68K bus access on both CPUs.
static int f; f = (f&0xff) + 0x4c; // 0.3
z80_subCLeft(3+(f>>8)); // 3.3 per kabuto
// don't use SekCyclesBurn(7) here since the Z80 doesn't run in cycle lock to
// the 68K. Count the stolen cycles to be accounted later in the 68K CPU runs
Pico.t.z80_buscycles += 7;
// 68k bus access delay=3.3 per kabuto, but for notaz picotest 3.0<delay<3.3
access_68k_bus(0x340); // // Q8, picotest: 0x301(>3.0)-0x34c(<3.3)
addr68k = Pico.m.z80_bank68k << 15;
addr68k += a & 0x7fff;

5
pico/pico_int.h
View file

@ -204,8 +204,8 @@ extern struct DrZ80 drZ80;
#define z80_cyclesDone() \
(Pico.t.z80c_aim - z80_cyclesLeft)
// one line has 488 68K cycles and 228 Z80 cycles, 228/488*8192=3827
#define cycles_68k_to_z80(x) ((x) * 3847 >> 13)
// 68k clock = OSC/7, z80 clock = OSC/15, 68k:z80 ratio = 7/15*8192=3822.9
#define cycles_68k_to_z80(x) ((x) * 3823 >> 13)
// ----------------------- SH2 CPU -----------------------
@ -449,6 +449,7 @@ struct PicoTiming
unsigned int z80c_line_start;
int z80_scanline;
int z80_buscycles;
int z80_busdelay;
int timer_a_next_oflow, timer_a_step; // in z80 cycles
int timer_b_next_oflow, timer_b_step;