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gb6
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more relative jumps

This commit is contained in:
Matt Laux 2019-04-25 00:29:42 -05:00
parent b6966cb605
commit a9696e5c7c
1 changed files with 14 additions and 8 deletions
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22
src/cpu.c
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@ -240,9 +240,10 @@ static void subtract(struct cpu *cpu, u8 value, int with_carry, int just_compare
static void push(struct cpu *cpu, u16 value)
{
printf("sp=%04x\n", cpu->sp);
printf("memory[sp-2] = %02x\n", value & 0xff);
printf("memory[sp-1] = %02x\n", value >> 8);
// todo #if DEBUG or something
//printf("sp=%04x\n", cpu->sp);
//printf("memory[sp-2] = %02x\n", value & 0xff);
//printf("memory[sp-1] = %02x\n", value >> 8);
write8(cpu, cpu->sp - 2, value & 0xff);
write8(cpu, cpu->sp - 1, value >> 8);
cpu->sp -= 2;
@ -251,9 +252,9 @@ static void push(struct cpu *cpu, u16 value)
static u16 pop(struct cpu *cpu)
{
cpu->sp += 2;
printf("sp=%04x\n", cpu->sp);
printf("read memory[sp-2] = %02x\n", read8(cpu, cpu->sp - 2));
printf("read memory[sp-1] = %02x\n", read8(cpu, cpu->sp - 1));
//printf("sp=%04x\n", cpu->sp);
//printf("read memory[sp-2] = %02x\n", read8(cpu, cpu->sp - 2));
//printf("read memory[sp-1] = %02x\n", read8(cpu, cpu->sp - 1));
return read8(cpu, cpu->sp - 1) << 8 | read8(cpu, cpu->sp - 2);
}
@ -516,9 +517,14 @@ void cpu_step(struct cpu *cpu)
case 0x12: // LD (DE),A
write8(cpu, read_de(cpu), cpu->a);
break;
case 0x20: // JR NZ,r8
case 0x18: // JR r8
temp = read8(cpu, cpu->pc);
if (!flag_isset(cpu, FLAG_ZERO)) {
cpu->pc += *((signed char *) &temp) + 1;
break;
case 0x20: // JR NZ,r8
case 0x28: // JR Z,r8
temp = read8(cpu, cpu->pc);
if ((opc == 0x20) ^ flag_isset(cpu, FLAG_ZERO)) {
cpu->pc += *((signed char *) &temp) + 1;
} else {
cpu->pc++;