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update lcd every 456 cycles

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This commit is contained in:
Matthew Laux 2022-06-20 19:46:32 -05:00
parent 3d6d3a0171
commit b0c690c693
4 changed files with 15 additions and 8 deletions
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3
cli/emulator.c
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@ -32,7 +32,8 @@ int main(int argc, char *argv[])
cpu.pc = 0;
for (executed = 0; executed < 100000; executed++) {
// for (executed = 0; executed < 100000; executed++) {
while (1) {
dmg_step(&dmg);
}

15
src/cpu.c
View File

@ -300,6 +300,9 @@ static void extended_insn(struct cpu *cpu, u8 insn)
shift_right // TODO SRL
};
printf(" %s\n", instructions[insn + 0x100].format);
cpu->cycle_count += instructions[insn + 0x100].cycles;
switch (op) {
case 0:
write_reg(cpu, reg, funcs[bit](cpu, read_reg(cpu, reg)));
@ -330,6 +333,7 @@ void cpu_step(struct cpu *cpu)
u8 opc = cpu->mem_read(cpu->mem_model, cpu->pc);
printf("0x%04x %s\n", cpu->pc, instructions[opc].format);
cpu->pc++;
cpu->cycle_count += instructions[opc].cycles;
switch (opc) {
case 0: // NOP
break;
@ -500,6 +504,7 @@ void cpu_step(struct cpu *cpu)
temp = read8(cpu, cpu->pc);
if ((opc == 0x20) ^ flag_isset(cpu, FLAG_ZERO)) {
cpu->pc += *((signed char *) &temp) + 1;
cpu->cycle_count += instructions[opc].cycles_branch - instructions[opc].cycles;
} else {
cpu->pc++;
}
@ -650,19 +655,19 @@ void cpu_step(struct cpu *cpu)
add(cpu, read8(cpu, cpu->pc), 1);
cpu->pc++;
break;
case 0xe0: // LDH (a8),A
write16(cpu, 0xff00 + read8(cpu, cpu->pc), cpu->a);
case 0xe0: // LD (a8),A
write8(cpu, 0xff00 + read8(cpu, cpu->pc), cpu->a);
cpu->pc++;
break;
case 0xe2: // LD (C),A
write8(cpu, 0xff00 + cpu->c, cpu->a);
break;
case 0xea: // LD (a16),A
write16(cpu, read16(cpu, cpu->pc), cpu->a);
write8(cpu, read16(cpu, cpu->pc), cpu->a);
cpu->pc += 2;
break;
case 0xf0: // LDH A,(a8)
cpu->a = read16(cpu, 0xff00 + read8(cpu, cpu->pc));
case 0xf0: // LD A,(a8)
cpu->a = read8(cpu, 0xff00 + read8(cpu, cpu->pc));
cpu->pc++;
break;
case 0xf2: // LD A,(C)

4
src/dmg.c
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@ -75,8 +75,8 @@ void dmg_step(void *_dmg)
// all other hw
cpu_step(dmg->cpu);
if (dmg->cpu->pc % 456 == 0) {
// each line takes 456 cycles
// each line takes 456 cycles
if (dmg->cpu->cycle_count % 456 == 0) {
lcd_step(dmg->lcd);
}
}

1
src/lcd.c
View File

@ -49,4 +49,5 @@ void lcd_step(struct lcd *lcd)
// step to next scanline 0-153
u8 next_scanline = (lcd_read(lcd, REG_LY) + 1) % 154;
lcd_write(lcd, REG_LY, next_scanline);
// printf("update lcd %d\n", next_scanline);
}