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Correct (disconnected) serial emulation.

This commit is contained in:
Lior Halphon 2016-09-05 22:13:28 +03:00
parent ab2e532cc3
commit 603b8969ab
4 changed files with 27 additions and 6 deletions
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4
Core/gb.c
View File

@ -111,8 +111,8 @@ void GB_init(GB_gameboy_t *gb)
gb->cartridge_type = &GB_cart_defs[0]; // Default cartridge type
gb->io_registers[GB_IO_OBP0] = gb->io_registers[GB_IO_OBP1] = 0xFF;
gb->io_registers[GB_IO_JOYP] = 0xF;
gb->io_registers[GB_IO_SC] = 0x7E;
}
void GB_init_cgb(GB_gameboy_t *gb)
@ -134,8 +134,8 @@ void GB_init_cgb(GB_gameboy_t *gb)
gb->cartridge_type = &GB_cart_defs[0]; // Default cartridge type
gb->io_registers[GB_IO_OBP0] = gb->io_registers[GB_IO_OBP1] = 0xFF;
gb->io_registers[GB_IO_JOYP] = 0xF;
gb->io_registers[GB_IO_SC] = 0x7C;
}
void GB_free(GB_gameboy_t *gb)

1
Core/gb.h
View File

@ -295,6 +295,7 @@ typedef struct GB_gameboy_s {
GB_PADDING(uint32_t, dma_cycles);
GB_aligned_double apu_cycles;
uint8_t tima_reload_state; /* After TIMA overflows, it becomes 0 for 4 cycles before actually reloading. */
uint16_t serial_cycles;
);
/* APU */

16
Core/memory.c
View File

@ -162,6 +162,7 @@ static uint8_t read_high_memory(GB_gameboy_t *gb, uint16_t addr)
case GB_IO_OBP1:
case GB_IO_WY:
case GB_IO_WX:
case GB_IO_SC:
case GB_IO_SB:
return gb->io_registers[addr & 0xFF];
case GB_IO_TIMA:
@ -220,8 +221,6 @@ static uint8_t read_high_memory(GB_gameboy_t *gb, uint16_t addr)
}
return ret;
}
case GB_IO_SC: /* Serial not supported yet */
return 0x7E;
default:
if ((addr & 0xFF) >= GB_IO_NR10 && (addr & 0xFF) <= GB_IO_WAV_END) {
return GB_apu_read(gb, addr & 0xFF);
@ -521,10 +520,19 @@ static void write_high_memory(GB_gameboy_t *gb, uint16_t addr, uint8_t value)
gb->hdma_cycles = 0;
return;
/* Todo: what happens when starting a transfer during a transfer?
What happens when starting a transfer during external clock?
*/
case GB_IO_SC:
if (!gb->cgb_mode) {
value |= 2;
}
gb->io_registers[GB_IO_SC] = value | (~0x83);
if ((value & 0x80) && (value & 0x1) ) {
gb->io_registers[GB_IO_SB] = 0xFF;
gb->io_registers[GB_IO_IF] |= 0x8;
gb->serial_cycles = gb->cgb_mode && (value & 2)? 128 : 4096;
}
else {
gb->serial_cycles = 0;
}
return;

12
Core/timing.c
View File

@ -41,6 +41,18 @@ void GB_advance_cycles(GB_gameboy_t *gb, uint8_t cycles)
}
}
if (gb->serial_cycles) {
if (gb->serial_cycles <= cycles) {
gb->serial_cycles = 0;
gb->io_registers[GB_IO_SC] &= ~0x80;
gb->io_registers[GB_IO_SB] = 0xFF;
gb->io_registers[GB_IO_IF] |= 8;
}
else {
gb->serial_cycles -= cycles;
}
}
if (gb->cgb_double_speed) {
cycles >>=1;
}