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-rw-r--r--blastem.c43
1 files changed, 25 insertions, 18 deletions
diff --git a/blastem.c b/blastem.c
index 4b6cffc..b9a1b6a 100644
--- a/blastem.c
+++ b/blastem.c
@@ -125,7 +125,6 @@ void adjust_int_cycle(m68k_context * context, vdp_context * v_context)
}
int break_on_sync = 0;
-#define Z80_ACK_DELAY 3 //TODO: Calculate this on the fly based on how synced up the Z80 and 68K clocks are
uint8_t reset = 1;
uint8_t need_reset = 0;
@@ -159,6 +158,8 @@ void sync_z80(z80_context * z_context, uint32_t mclks)
z80_run(z_context);
dprintf("Z80 ran to cycle %d\n", z_context->current_cycle);
}
+ } else {
+ z_context->current_cycle = mclks / MCLKS_PER_Z80;
}
}
@@ -354,6 +355,11 @@ void io_data_read(io_port * pad, m68k_context * context)
}
uint32_t zram_counter = 0;
+#define Z80_ACK_DELAY 3
+#define Z80_BUSY_DELAY 2//TODO: Find the actual value for this
+#define Z80_REQ_BUSY 1
+#define Z80_REQ_ACK 0
+#define Z80_RES_BUSACK reset
m68k_context * io_write(uint32_t location, m68k_context * context, uint8_t value)
{
@@ -410,8 +416,8 @@ m68k_context * io_write(uint32_t location, m68k_context * context, uint8_t value
dputs("bus requesting Z80");
busreq = 1;
if(!reset) {
- busack_cycle = context->current_cycle + Z80_ACK_DELAY;
- new_busack = 0;
+ busack_cycle = ((gen->z80->current_cycle + Z80_ACK_DELAY) * MCLKS_PER_Z80) / MCLKS_PER_68K;//context->current_cycle + Z80_ACK_DELAY;
+ new_busack = Z80_REQ_ACK;
}
} else {
if (busreq) {
@@ -424,18 +430,19 @@ m68k_context * io_write(uint32_t location, m68k_context * context, uint8_t value
fclose(f);
#endif
//TODO: Add necessary delay between release of busreq and resumption of execution
- gen->z80->current_cycle = (context->current_cycle * MCLKS_PER_68K) / MCLKS_PER_Z80;
}
busreq = 0;
- busack_cycle = CYCLE_NEVER;
- busack = 1;
+ //busack_cycle = CYCLE_NEVER;
+ //busack = Z80_REQ_BUSY;
+ busack_cycle = ((gen->z80->current_cycle + Z80_BUSY_DELAY) * MCLKS_PER_Z80) / MCLKS_PER_68K;
+ new_busack = Z80_REQ_BUSY;
}
} else if (location == 0x1200) {
sync_z80(gen->z80, context->current_cycle * MCLKS_PER_68K);
if (value & 1) {
if (reset && busreq) {
new_busack = 0;
- busack_cycle = context->current_cycle + Z80_ACK_DELAY;
+ busack_cycle = ((gen->z80->current_cycle + Z80_ACK_DELAY) * MCLKS_PER_Z80) / MCLKS_PER_68K;//context->current_cycle + Z80_ACK_DELAY;
}
//TODO: Deal with the scenario in which reset is not asserted long enough
if (reset) {
@@ -509,8 +516,8 @@ m68k_context * io_write_w(uint32_t location, m68k_context * context, uint16_t va
dprintf("bus requesting Z80 @ %d\n", (context->current_cycle * MCLKS_PER_68K) / MCLKS_PER_Z80);
busreq = 1;
if(!reset) {
- busack_cycle = context->current_cycle + Z80_ACK_DELAY;
- new_busack = 0;
+ busack_cycle = ((gen->z80->current_cycle + Z80_ACK_DELAY) * MCLKS_PER_Z80) / MCLKS_PER_68K;//context->current_cycle + Z80_ACK_DELAY;
+ new_busack = Z80_REQ_ACK;
}
} else {
if (busreq) {
@@ -523,24 +530,24 @@ m68k_context * io_write_w(uint32_t location, m68k_context * context, uint16_t va
fclose(f);
#endif
//TODO: Add necessary delay between release of busreq and resumption of execution
- gen->z80->current_cycle = (context->current_cycle * MCLKS_PER_68K) / MCLKS_PER_Z80;
}
busreq = 0;
- busack_cycle = CYCLE_NEVER;
- busack = 1;
+ //busack_cycle = CYCLE_NEVER;
+ //busack = Z80_REQ_BUSY;
+ busack_cycle = ((gen->z80->current_cycle + Z80_BUSY_DELAY) * MCLKS_PER_Z80) / MCLKS_PER_68K;
+ new_busack = Z80_REQ_BUSY;
}
} else if (location == 0x1200) {
sync_z80(gen->z80, context->current_cycle * MCLKS_PER_68K);
if (value & 0x100) {
if (reset && busreq) {
new_busack = 0;
- busack_cycle = context->current_cycle + Z80_ACK_DELAY;
+ busack_cycle = ((gen->z80->current_cycle + Z80_ACK_DELAY) * MCLKS_PER_Z80) / MCLKS_PER_68K;//context->current_cycle + Z80_ACK_DELAY;
}
//TODO: Deal with the scenario in which reset is not asserted long enough
if (reset) {
need_reset = 1;
//TODO: Add necessary delay between release of reset and start of execution
- gen->z80->current_cycle = (context->current_cycle * MCLKS_PER_68K) / MCLKS_PER_Z80;
}
reset = 0;
} else {
@@ -566,7 +573,7 @@ m68k_context * io_read(uint32_t location, m68k_context * context)
busack = new_busack;
busack_cycle = CYCLE_NEVER;
}
- if (!(busack || reset)) {
+ if (!(busack==Z80_REQ_BUSY || reset)) {
location &= 0x7FFF;
if (location < 0x4000) {
context->value = z80_ram[location & 0x1FFF];
@@ -610,7 +617,7 @@ m68k_context * io_read(uint32_t location, m68k_context * context)
busack = new_busack;
busack_cycle = CYCLE_NEVER;
}
- context->value = reset || busack;
+ context->value = Z80_RES_BUSACK || busack;
//printf("Byte read of BUSREQ returned %d @ %d (reset: %d, busack: %d)\n", context->value, context->current_cycle, reset, busack);
} else if (location == 0x1200) {
context->value = !reset;
@@ -630,7 +637,7 @@ m68k_context * io_read_w(uint32_t location, m68k_context * context)
busack = new_busack;
busack_cycle = CYCLE_NEVER;
}
- if (!(busack || reset)) {
+ if (!(busack==Z80_REQ_BUSY || reset)) {
location &= 0x7FFF;
uint16_t value;
if (location < 0x4000) {
@@ -682,7 +689,7 @@ m68k_context * io_read_w(uint32_t location, m68k_context * context)
busack = new_busack;
busack_cycle = CYCLE_NEVER;
}
- context->value = (reset || busack) << 8;
+ context->value = (Z80_RES_BUSACK || busack) << 8;
//printf("Word read of BUSREQ returned %d\n", context->value);
} else if (location == 0x1200) {
context->value = (!reset) << 8;
generated by cgit v1.2.3 (git 2.25.1) at 2025-06-19 19:48:13 +0000