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SameBoy/Core/z80_cpu.c

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#include <stdio.h>
#include <stdbool.h>
#include "gb.h"
typedef void GB_opcode_t(GB_gameboy_t *gb, uint8_t opcode);
static void ill(GB_gameboy_t *gb, uint8_t opcode)
{
GB_log(gb, "Illegal Opcode. Halting.\n");
gb->interrupt_enable = 0;
gb->halted = true;
}
static void nop(GB_gameboy_t *gb, uint8_t opcode)
{
GB_advance_cycles(gb, 4);
}
static void stop(GB_gameboy_t *gb, uint8_t opcode)
{
GB_advance_cycles(gb, 4);
if (gb->io_registers[GB_IO_KEY1] & 0x1) {
/* Make sure we don't leave display_cycles not divisble by 8 in single speed mode */
if (gb->display_cycles % 8 == 4) {
GB_advance_cycles(gb, 4);
}
/* Todo: the switch is not instant. We should emulate this. */
gb->cgb_double_speed ^= true;
gb->io_registers[GB_IO_KEY1] = 0;
}
else {
gb->stopped = true;
}
gb->pc++;
}
/* Operand naming conventions for functions:
r = 8-bit register
lr = low 8-bit register
hr = high 8-bit register
rr = 16-bit register
d8 = 8-bit imm
d16 = 16-bit imm
d.. = [..]
cc = condition code (z, nz, c, nc)
*/
static void ld_rr_d16(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t register_id;
uint16_t value;
GB_advance_cycles(gb, 4);
register_id = (opcode >> 4) + 1;
value = GB_read_memory(gb, gb->pc++);
GB_advance_cycles(gb, 4);
value |= GB_read_memory(gb, gb->pc++) << 8;
GB_advance_cycles(gb, 4);
gb->registers[register_id] = value;
}
static void ld_drr_a(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t register_id;
GB_advance_cycles(gb, 4);
register_id = (opcode >> 4) + 1;
GB_write_memory(gb, gb->registers[register_id], gb->registers[GB_REGISTER_AF] >> 8);
GB_advance_cycles(gb, 4);
}
static void inc_rr(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t register_id;
GB_advance_cycles(gb, 8);
register_id = (opcode >> 4) + 1;
gb->registers[register_id]++;
}
static void inc_hr(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t register_id;
GB_advance_cycles(gb, 4);
register_id = ((opcode >> 4) + 1) & 0x03;
gb->registers[register_id] += 0x100;
gb->registers[GB_REGISTER_AF] &= ~(GB_SUBSTRACT_FLAG | GB_ZERO_FLAG | GB_HALF_CARRY_FLAG);
if ((gb->registers[register_id] & 0x0F00) == 0) {
gb->registers[GB_REGISTER_AF] |= GB_HALF_CARRY_FLAG;
}
if ((gb->registers[register_id] & 0xFF00) == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
}
static void dec_hr(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t register_id;
GB_advance_cycles(gb, 4);
register_id = ((opcode >> 4) + 1) & 0x03;
gb->registers[register_id] -= 0x100;
gb->registers[GB_REGISTER_AF] &= ~(GB_ZERO_FLAG | GB_HALF_CARRY_FLAG);
gb->registers[GB_REGISTER_AF] |= GB_SUBSTRACT_FLAG;
if ((gb->registers[register_id] & 0x0F00) == 0xF00) {
gb->registers[GB_REGISTER_AF] |= GB_HALF_CARRY_FLAG;
}
if ((gb->registers[register_id] & 0xFF00) == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
}
static void ld_hr_d8(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t register_id;
GB_advance_cycles(gb, 4);
register_id = ((opcode >> 4) + 1) & 0x03;
gb->registers[register_id] &= 0xFF;
gb->registers[register_id] |= GB_read_memory(gb, gb->pc++) << 8;
GB_advance_cycles(gb, 4);
}
static void rlca(GB_gameboy_t *gb, uint8_t opcode)
{
bool carry = (gb->registers[GB_REGISTER_AF] & 0x8000) != 0;
GB_advance_cycles(gb, 4);
gb->registers[GB_REGISTER_AF] = (gb->registers[GB_REGISTER_AF] & 0xFF00) << 1;
if (carry) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG | 0x0100;
}
}
static void rla(GB_gameboy_t *gb, uint8_t opcode)
{
bool bit7 = (gb->registers[GB_REGISTER_AF] & 0x8000) != 0;
bool carry = (gb->registers[GB_REGISTER_AF] & GB_CARRY_FLAG) != 0;
GB_advance_cycles(gb, 4);
gb->registers[GB_REGISTER_AF] = (gb->registers[GB_REGISTER_AF] & 0xFF00) << 1;
if (carry) {
gb->registers[GB_REGISTER_AF] |= 0x0100;
}
if (bit7) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
}
static void ld_da16_sp(GB_gameboy_t *gb, uint8_t opcode)
{
/* Todo: Verify order is correct */
uint16_t addr;
GB_advance_cycles(gb, 4);
addr = GB_read_memory(gb, gb->pc++);
GB_advance_cycles(gb, 4);
addr |= GB_read_memory(gb, gb->pc++) << 8;
GB_advance_cycles(gb, 4);
GB_write_memory(gb, addr, gb->registers[GB_REGISTER_SP] & 0xFF);
GB_advance_cycles(gb, 4);
GB_write_memory(gb, addr+1, gb->registers[GB_REGISTER_SP] >> 8);
GB_advance_cycles(gb, 4);
}
static void add_hl_rr(GB_gameboy_t *gb, uint8_t opcode)
{
uint16_t hl = gb->registers[GB_REGISTER_HL];
uint16_t rr;
uint8_t register_id;
GB_advance_cycles(gb, 8);
register_id = (opcode >> 4) + 1;
rr = gb->registers[register_id];
gb->registers[GB_REGISTER_HL] = hl + rr;
gb->registers[GB_REGISTER_AF] &= ~(GB_SUBSTRACT_FLAG | GB_CARRY_FLAG | GB_HALF_CARRY_FLAG);
/* The meaning of the Half Carry flag is really hard to track -_- */
if (((hl & 0xFFF) + (rr & 0xFFF)) & 0x1000) {
gb->registers[GB_REGISTER_AF] |= GB_HALF_CARRY_FLAG;
}
if ( ((unsigned long) hl) + ((unsigned long) rr) & 0x10000) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
}
static void ld_a_drr(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t register_id;
register_id = (opcode >> 4) + 1;
GB_advance_cycles(gb, 4);
gb->registers[GB_REGISTER_AF] &= 0xFF;
gb->registers[GB_REGISTER_AF] |= GB_read_memory(gb, gb->registers[register_id]) << 8;
GB_advance_cycles(gb, 4);
}
static void dec_rr(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t register_id;
GB_advance_cycles(gb, 8);
register_id = (opcode >> 4) + 1;
gb->registers[register_id]--;
}
static void inc_lr(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t register_id;
uint8_t value;
GB_advance_cycles(gb, 4);
register_id = (opcode >> 4) + 1;
value = (gb->registers[register_id] & 0xFF) + 1;
gb->registers[register_id] = (gb->registers[register_id] & 0xFF00) | value;
gb->registers[GB_REGISTER_AF] &= ~(GB_SUBSTRACT_FLAG | GB_ZERO_FLAG | GB_HALF_CARRY_FLAG);
if ((gb->registers[register_id] & 0x0F) == 0) {
gb->registers[GB_REGISTER_AF] |= GB_HALF_CARRY_FLAG;
}
if ((gb->registers[register_id] & 0xFF) == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
}
static void dec_lr(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t register_id;
uint8_t value;
GB_advance_cycles(gb, 4);
register_id = (opcode >> 4) + 1;
value = (gb->registers[register_id] & 0xFF) - 1;
gb->registers[register_id] = (gb->registers[register_id] & 0xFF00) | value;
gb->registers[GB_REGISTER_AF] &= ~(GB_ZERO_FLAG | GB_HALF_CARRY_FLAG);
gb->registers[GB_REGISTER_AF] |= GB_SUBSTRACT_FLAG;
if ((gb->registers[register_id] & 0x0F) == 0xF) {
gb->registers[GB_REGISTER_AF] |= GB_HALF_CARRY_FLAG;
}
if ((gb->registers[register_id] & 0xFF) == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
}
static void ld_lr_d8(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t register_id;
GB_advance_cycles(gb, 4);
register_id = (opcode >> 4) + 1;
gb->registers[register_id] &= 0xFF00;
gb->registers[register_id] |= GB_read_memory(gb, gb->pc++);
GB_advance_cycles(gb, 4);
}
static void rrca(GB_gameboy_t *gb, uint8_t opcode)
{
bool carry = (gb->registers[GB_REGISTER_AF] & 0x100) != 0;
GB_advance_cycles(gb, 4);
gb->registers[GB_REGISTER_AF] = (gb->registers[GB_REGISTER_AF] >> 1) & 0xFF00;
if (carry) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG | 0x8000;
}
}
static void rra(GB_gameboy_t *gb, uint8_t opcode)
{
bool bit1 = (gb->registers[GB_REGISTER_AF] & 0x0100) != 0;
bool carry = (gb->registers[GB_REGISTER_AF] & GB_CARRY_FLAG) != 0;
GB_advance_cycles(gb, 4);
gb->registers[GB_REGISTER_AF] = (gb->registers[GB_REGISTER_AF] >> 1) & 0xFF00;
if (carry) {
gb->registers[GB_REGISTER_AF] |= 0x8000;
}
if (bit1) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
}
static void jr_r8(GB_gameboy_t *gb, uint8_t opcode)
{
/* Todo: Verify cycles are not 8 and 4 instead */
GB_advance_cycles(gb, 4);
gb->pc += (int8_t)GB_read_memory(gb, gb->pc) + 1;
GB_advance_cycles(gb, 8);
}
static bool condition_code(GB_gameboy_t *gb, uint8_t opcode)
{
switch ((opcode >> 3) & 0x3) {
case 0:
return !(gb->registers[GB_REGISTER_AF] & GB_ZERO_FLAG);
case 1:
return (gb->registers[GB_REGISTER_AF] & GB_ZERO_FLAG);
case 2:
return !(gb->registers[GB_REGISTER_AF] & GB_CARRY_FLAG);
case 3:
return (gb->registers[GB_REGISTER_AF] & GB_CARRY_FLAG);
}
return false;
}
static void jr_cc_r8(GB_gameboy_t *gb, uint8_t opcode)
{
if (condition_code(gb, opcode)) {
GB_advance_cycles(gb, 4);
gb->pc += (int8_t)GB_read_memory(gb, gb->pc) + 1;
GB_advance_cycles(gb, 8);
}
else {
GB_advance_cycles(gb, 8);
gb->pc += 1;
}
}
static void daa(GB_gameboy_t *gb, uint8_t opcode)
{
/* This function is UGLY and UNREADABLE! But it passes Blargg's daa test! */
GB_advance_cycles(gb, 4);
gb->registers[GB_REGISTER_AF] &= ~GB_ZERO_FLAG;
if (gb->registers[GB_REGISTER_AF] & GB_SUBSTRACT_FLAG) {
if (gb->registers[GB_REGISTER_AF] & GB_HALF_CARRY_FLAG) {
gb->registers[GB_REGISTER_AF] &= ~GB_HALF_CARRY_FLAG;
if (gb->registers[GB_REGISTER_AF] & GB_CARRY_FLAG) {
gb->registers[GB_REGISTER_AF] += 0x9A00;
}
else {
gb->registers[GB_REGISTER_AF] += 0xFA00;
}
}
else if(gb->registers[GB_REGISTER_AF] & GB_CARRY_FLAG) {
gb->registers[GB_REGISTER_AF] += 0xA000;
}
}
else {
if (gb->registers[GB_REGISTER_AF] & GB_HALF_CARRY_FLAG) {
uint16_t number = gb->registers[GB_REGISTER_AF] >> 8;
if (gb->registers[GB_REGISTER_AF] & GB_CARRY_FLAG) {
number += 0x100;
}
gb->registers[GB_REGISTER_AF] = 0;
number += 0x06;
if (number >= 0xa0) {
number -= 0xa0;
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
gb->registers[GB_REGISTER_AF] |= number << 8;
}
else {
uint16_t number = gb->registers[GB_REGISTER_AF] >> 8;
if (gb->registers[GB_REGISTER_AF] & GB_CARRY_FLAG) {
number += 0x100;
}
if (number > 0x99) {
number += 0x60;
}
number = (number & 0x0F) + ((number & 0x0F) > 9 ? 6 : 0) + (number & 0xFF0);
gb->registers[GB_REGISTER_AF] = number << 8;
if (number & 0xFF00) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
}
}
if ((gb->registers[GB_REGISTER_AF] & 0xFF00) == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
}
static void cpl(GB_gameboy_t *gb, uint8_t opcode)
{
GB_advance_cycles(gb, 4);
gb->registers[GB_REGISTER_AF] ^= 0xFF00;
gb->registers[GB_REGISTER_AF] |= GB_HALF_CARRY_FLAG | GB_SUBSTRACT_FLAG;
}
static void scf(GB_gameboy_t *gb, uint8_t opcode)
{
GB_advance_cycles(gb, 4);
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
gb->registers[GB_REGISTER_AF] &= ~(GB_HALF_CARRY_FLAG | GB_SUBSTRACT_FLAG);
}
static void ccf(GB_gameboy_t *gb, uint8_t opcode)
{
GB_advance_cycles(gb, 4);
gb->registers[GB_REGISTER_AF] ^= GB_CARRY_FLAG;
gb->registers[GB_REGISTER_AF] &= ~(GB_HALF_CARRY_FLAG | GB_SUBSTRACT_FLAG);
}
static void ld_dhli_a(GB_gameboy_t *gb, uint8_t opcode)
{
GB_advance_cycles(gb, 4);
GB_write_memory(gb, gb->registers[GB_REGISTER_HL]++, gb->registers[GB_REGISTER_AF] >> 8);
GB_advance_cycles(gb, 4);
}
static void ld_dhld_a(GB_gameboy_t *gb, uint8_t opcode)
{
GB_advance_cycles(gb, 4);
GB_write_memory(gb, gb->registers[GB_REGISTER_HL]--, gb->registers[GB_REGISTER_AF] >> 8);
GB_advance_cycles(gb, 4);
}
static void ld_a_dhli(GB_gameboy_t *gb, uint8_t opcode)
{
GB_advance_cycles(gb, 4);
gb->registers[GB_REGISTER_AF] &= 0xFF;
gb->registers[GB_REGISTER_AF] |= GB_read_memory(gb, gb->registers[GB_REGISTER_HL]++) << 8;
GB_advance_cycles(gb, 4);
}
static void ld_a_dhld(GB_gameboy_t *gb, uint8_t opcode)
{
GB_advance_cycles(gb, 4);
gb->registers[GB_REGISTER_AF] &= 0xFF;
gb->registers[GB_REGISTER_AF] |= GB_read_memory(gb, gb->registers[GB_REGISTER_HL]--) << 8;
GB_advance_cycles(gb, 4);
}
static void inc_dhl(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t value;
GB_advance_cycles(gb, 4);
value = GB_read_memory(gb, gb->registers[GB_REGISTER_HL]) + 1;
GB_advance_cycles(gb, 4);
GB_write_memory(gb, gb->registers[GB_REGISTER_HL], value);
GB_advance_cycles(gb, 4);
gb->registers[GB_REGISTER_AF] &= ~(GB_SUBSTRACT_FLAG | GB_ZERO_FLAG | GB_HALF_CARRY_FLAG);
if ((value & 0x0F) == 0) {
gb->registers[GB_REGISTER_AF] |= GB_HALF_CARRY_FLAG;
}
if ((value & 0xFF) == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
}
static void dec_dhl(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t value;
GB_advance_cycles(gb, 4);
value = GB_read_memory(gb, gb->registers[GB_REGISTER_HL]) - 1;
GB_advance_cycles(gb, 4);
GB_write_memory(gb, gb->registers[GB_REGISTER_HL], value);
GB_advance_cycles(gb, 4);
gb->registers[GB_REGISTER_AF] &= ~( GB_ZERO_FLAG | GB_HALF_CARRY_FLAG);
gb->registers[GB_REGISTER_AF] |= GB_SUBSTRACT_FLAG;
if ((value & 0x0F) == 0x0F) {
gb->registers[GB_REGISTER_AF] |= GB_HALF_CARRY_FLAG;
}
if ((value & 0xFF) == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
}
static void ld_dhl_d8(GB_gameboy_t *gb, uint8_t opcode)
{
GB_advance_cycles(gb, 4);
uint8_t data = GB_read_memory(gb, gb->pc++);
GB_advance_cycles(gb, 4);
GB_write_memory(gb, gb->registers[GB_REGISTER_HL], data);
GB_advance_cycles(gb, 4);
}
uint8_t get_src_value(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t src_register_id;
uint8_t src_low;
src_register_id = ((opcode >> 1) + 1) & 3;
src_low = opcode & 1;
if (src_register_id == GB_REGISTER_AF) {
if (src_low) {
return gb->registers[GB_REGISTER_AF] >> 8;
}
uint8_t ret = GB_read_memory(gb, gb->registers[GB_REGISTER_HL]);
GB_advance_cycles(gb, 4);
return ret;
}
if (src_low) {
return gb->registers[src_register_id] & 0xFF;
}
return gb->registers[src_register_id] >> 8;
}
static void set_src_value(GB_gameboy_t *gb, uint8_t opcode, uint8_t value)
{
uint8_t src_register_id;
uint8_t src_low;
src_register_id = ((opcode >> 1) + 1) & 3;
src_low = opcode & 1;
if (src_register_id == GB_REGISTER_AF) {
if (src_low) {
gb->registers[GB_REGISTER_AF] &= 0xFF;
gb->registers[GB_REGISTER_AF] |= value << 8;
}
else {
GB_write_memory(gb, gb->registers[GB_REGISTER_HL], value);
GB_advance_cycles(gb, 4);
}
}
else {
if (src_low) {
gb->registers[src_register_id] &= 0xFF00;
gb->registers[src_register_id] |= value;
}
else {
gb->registers[src_register_id] &= 0xFF;
gb->registers[src_register_id] |= value << 8;
}
}
}
/* The LD r,r instruction is extremely common and extremely simple. Decoding this opcode at runtime is a significent
performance hit, so we generate functions for every ld x,y couple (including [hl]) at compile time using macros. */
/* Todo: It's probably wise to do the same to all opcodes. */
#define LD_X_Y(x, y) \
static void ld_##x##_##y(GB_gameboy_t *gb, uint8_t opcode) \
{ \
GB_advance_cycles(gb, 4); \
gb->x = gb->y;\
}
#define LD_X_DHL(x) \
static void ld_##x##_##dhl(GB_gameboy_t *gb, uint8_t opcode) \
{ \
GB_advance_cycles(gb, 4); \
gb->x = GB_read_memory(gb, gb->registers[GB_REGISTER_HL]); \
GB_advance_cycles(gb, 4);\
}
#define LD_DHL_Y(y) \
static void ld_##dhl##_##y(GB_gameboy_t *gb, uint8_t opcode) \
{ \
GB_advance_cycles(gb, 4); \
GB_write_memory(gb, gb->registers[GB_REGISTER_HL], gb->y); \
GB_advance_cycles(gb, 4);\
}
LD_X_Y(b,c) LD_X_Y(b,d) LD_X_Y(b,e) LD_X_Y(b,h) LD_X_Y(b,l) LD_X_DHL(b) LD_X_Y(b,a)
LD_X_Y(c,b) LD_X_Y(c,d) LD_X_Y(c,e) LD_X_Y(c,h) LD_X_Y(c,l) LD_X_DHL(c) LD_X_Y(c,a)
LD_X_Y(d,b) LD_X_Y(d,c) LD_X_Y(d,e) LD_X_Y(d,h) LD_X_Y(d,l) LD_X_DHL(d) LD_X_Y(d,a)
LD_X_Y(e,b) LD_X_Y(e,c) LD_X_Y(e,d) LD_X_Y(e,h) LD_X_Y(e,l) LD_X_DHL(e) LD_X_Y(e,a)
LD_X_Y(h,b) LD_X_Y(h,c) LD_X_Y(h,d) LD_X_Y(h,e) LD_X_Y(h,l) LD_X_DHL(h) LD_X_Y(h,a)
LD_X_Y(l,b) LD_X_Y(l,c) LD_X_Y(l,d) LD_X_Y(l,e) LD_X_Y(l,h) LD_X_DHL(l) LD_X_Y(l,a)
LD_DHL_Y(b) LD_DHL_Y(c) LD_DHL_Y(d) LD_DHL_Y(e) LD_DHL_Y(h) LD_DHL_Y(l) LD_DHL_Y(a)
LD_X_Y(a,b) LD_X_Y(a,c) LD_X_Y(a,d) LD_X_Y(a,e) LD_X_Y(a,h) LD_X_Y(a,l) LD_X_DHL(a)
static void add_a_r(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t value, a;
GB_advance_cycles(gb, 4);
value = get_src_value(gb, opcode);
a = gb->registers[GB_REGISTER_AF] >> 8;
gb->registers[GB_REGISTER_AF] = (a + value) << 8;
if ((uint8_t)(a + value) == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
if ((a & 0xF) + (value & 0xF) > 0x0F) {
gb->registers[GB_REGISTER_AF] |= GB_HALF_CARRY_FLAG;
}
if (((unsigned long) a) + ((unsigned long) value) > 0xFF) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
}
static void adc_a_r(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t value, a, carry;
GB_advance_cycles(gb, 4);
value = get_src_value(gb, opcode);
a = gb->registers[GB_REGISTER_AF] >> 8;
carry = (gb->registers[GB_REGISTER_AF] & GB_CARRY_FLAG) != 0;
gb->registers[GB_REGISTER_AF] = (a + value + carry) << 8;
if ((uint8_t)(a + value + carry) == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
if ((a & 0xF) + (value & 0xF) + carry > 0x0F) {
gb->registers[GB_REGISTER_AF] |= GB_HALF_CARRY_FLAG;
}
if (((unsigned long) a) + ((unsigned long) value) + carry > 0xFF) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
}
static void sub_a_r(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t value, a;
GB_advance_cycles(gb, 4);
value = get_src_value(gb, opcode);
a = gb->registers[GB_REGISTER_AF] >> 8;
gb->registers[GB_REGISTER_AF] = ((a - value) << 8) | GB_SUBSTRACT_FLAG;
if (a == value) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
if ((a & 0xF) < (value & 0xF)) {
gb->registers[GB_REGISTER_AF] |= GB_HALF_CARRY_FLAG;
}
if (a < value) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
}
static void sbc_a_r(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t value, a, carry;
GB_advance_cycles(gb, 4);
value = get_src_value(gb, opcode);
a = gb->registers[GB_REGISTER_AF] >> 8;
carry = (gb->registers[GB_REGISTER_AF] & GB_CARRY_FLAG) != 0;
gb->registers[GB_REGISTER_AF] = ((a - value - carry) << 8) | GB_SUBSTRACT_FLAG;
if ((uint8_t) (a - value - carry) == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
if ((a & 0xF) < (value & 0xF) + carry) {
gb->registers[GB_REGISTER_AF] |= GB_HALF_CARRY_FLAG;
}
if (((unsigned long) a) - ((unsigned long) value) - carry > 0xFF) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
}
static void and_a_r(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t value, a;
GB_advance_cycles(gb, 4);
value = get_src_value(gb, opcode);
a = gb->registers[GB_REGISTER_AF] >> 8;
gb->registers[GB_REGISTER_AF] = ((a & value) << 8) | GB_HALF_CARRY_FLAG;
if ((a & value) == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
}
static void xor_a_r(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t value, a;
GB_advance_cycles(gb, 4);
value = get_src_value(gb, opcode);
a = gb->registers[GB_REGISTER_AF] >> 8;
gb->registers[GB_REGISTER_AF] = (a ^ value) << 8;
if ((a ^ value) == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
}
static void or_a_r(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t value, a;
GB_advance_cycles(gb, 4);
value = get_src_value(gb, opcode);
a = gb->registers[GB_REGISTER_AF] >> 8;
gb->registers[GB_REGISTER_AF] = (a | value) << 8;
if ((a | value) == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
}
static void cp_a_r(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t value, a;
GB_advance_cycles(gb, 4);
value = get_src_value(gb, opcode);
a = gb->registers[GB_REGISTER_AF] >> 8;
gb->registers[GB_REGISTER_AF] &= 0xFF00;
gb->registers[GB_REGISTER_AF] |= GB_SUBSTRACT_FLAG;
if (a == value) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
if ((a & 0xF) < (value & 0xF)) {
gb->registers[GB_REGISTER_AF] |= GB_HALF_CARRY_FLAG;
}
if (a < value) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
}
static void halt(GB_gameboy_t *gb, uint8_t opcode)
{
GB_advance_cycles(gb, 4);
gb->halted = true;
/* Despite what some online documentations say, the HALT bug also happens on a CGB, in both CGB and DMG modes. */
if (!gb->ime && (gb->interrupt_enable & gb->io_registers[GB_IO_IF] & 0x1F) != 0) {
gb->halted = false;
gb->halt_bug = true;
}
}
static void ret_cc(GB_gameboy_t *gb, uint8_t opcode)
{
/* Todo: Verify timing */
if (condition_code(gb, opcode)) {
GB_debugger_ret_hook(gb);
GB_advance_cycles(gb, 8);
gb->pc = GB_read_memory(gb, gb->registers[GB_REGISTER_SP]);
GB_advance_cycles(gb, 4);
gb->pc |= GB_read_memory(gb, gb->registers[GB_REGISTER_SP] + 1) << 8;
GB_advance_cycles(gb, 8);
gb->registers[GB_REGISTER_SP] += 2;
}
else {
GB_advance_cycles(gb, 8);
}
}
static void pop_rr(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t register_id;
GB_advance_cycles(gb, 4);
register_id = ((opcode >> 4) + 1) & 3;
gb->registers[register_id] = GB_read_memory(gb, gb->registers[GB_REGISTER_SP]);
GB_advance_cycles(gb, 4);
gb->registers[register_id] |= GB_read_memory(gb, gb->registers[GB_REGISTER_SP] + 1) << 8;
GB_advance_cycles(gb, 4);
gb->registers[GB_REGISTER_AF] &= 0xFFF0; // Make sure we don't set impossible flags on F! See Blargg's PUSH AF test.
gb->registers[GB_REGISTER_SP] += 2;
}
static void jp_cc_a16(GB_gameboy_t *gb, uint8_t opcode)
{
if (condition_code(gb, opcode)) {
GB_advance_cycles(gb, 4);
uint16_t addr = GB_read_memory(gb, gb->pc);
GB_advance_cycles(gb, 4);
addr |= (GB_read_memory(gb, gb->pc + 1) << 8);
GB_advance_cycles(gb, 8);
gb->pc = addr;
}
else {
GB_advance_cycles(gb, 12);
gb->pc += 2;
}
}
static void jp_a16(GB_gameboy_t *gb, uint8_t opcode)
{
GB_advance_cycles(gb, 4);
uint16_t addr = GB_read_memory(gb, gb->pc);
GB_advance_cycles(gb, 4);
addr |= (GB_read_memory(gb, gb->pc + 1) << 8);
GB_advance_cycles(gb, 8);
gb->pc = addr;}
static void call_cc_a16(GB_gameboy_t *gb, uint8_t opcode)
{
uint16_t call_addr = gb->pc - 1;
if (condition_code(gb, opcode)) {
GB_advance_cycles(gb, 4);
gb->registers[GB_REGISTER_SP] -= 2;
uint16_t addr = GB_read_memory(gb, gb->pc++);
GB_advance_cycles(gb, 4);
addr |= (GB_read_memory(gb, gb->pc++) << 8);
GB_advance_cycles(gb, 8);
GB_write_memory(gb, gb->registers[GB_REGISTER_SP] + 1, (gb->pc) >> 8);
GB_advance_cycles(gb, 4);
GB_write_memory(gb, gb->registers[GB_REGISTER_SP], (gb->pc) & 0xFF);
GB_advance_cycles(gb, 4);
gb->pc = addr;
GB_debugger_call_hook(gb, call_addr);
}
else {
GB_advance_cycles(gb, 12);
gb->pc += 2;
}
}
static void push_rr(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t register_id;
GB_advance_cycles(gb, 8);
register_id = ((opcode >> 4) + 1) & 3;
gb->registers[GB_REGISTER_SP] -= 2;
GB_write_memory(gb, gb->registers[GB_REGISTER_SP] + 1, (gb->registers[register_id]) >> 8);
GB_advance_cycles(gb, 4);
GB_write_memory(gb, gb->registers[GB_REGISTER_SP], (gb->registers[register_id]) & 0xFF);
GB_advance_cycles(gb, 4);
}
static void add_a_d8(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t value, a;
GB_advance_cycles(gb, 4);
value = GB_read_memory(gb, gb->pc++);
GB_advance_cycles(gb, 4);
a = gb->registers[GB_REGISTER_AF] >> 8;
gb->registers[GB_REGISTER_AF] = (a + value) << 8;
if ((uint8_t) (a + value) == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
if ((a & 0xF) + (value & 0xF) > 0x0F) {
gb->registers[GB_REGISTER_AF] |= GB_HALF_CARRY_FLAG;
}
if (((unsigned long) a) + ((unsigned long) value) > 0xFF) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
}
static void adc_a_d8(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t value, a, carry;
GB_advance_cycles(gb, 4);
value = GB_read_memory(gb, gb->pc++);
GB_advance_cycles(gb, 4);
a = gb->registers[GB_REGISTER_AF] >> 8;
carry = (gb->registers[GB_REGISTER_AF] & GB_CARRY_FLAG) != 0;
gb->registers[GB_REGISTER_AF] = (a + value + carry) << 8;
if (gb->registers[GB_REGISTER_AF] == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
if ((a & 0xF) + (value & 0xF) + carry > 0x0F) {
gb->registers[GB_REGISTER_AF] |= GB_HALF_CARRY_FLAG;
}
if (((unsigned long) a) + ((unsigned long) value) + carry > 0xFF) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
}
static void sub_a_d8(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t value, a;
GB_advance_cycles(gb, 4);
value = GB_read_memory(gb, gb->pc++);
GB_advance_cycles(gb, 4);
a = gb->registers[GB_REGISTER_AF] >> 8;
gb->registers[GB_REGISTER_AF] = ((a - value) << 8) | GB_SUBSTRACT_FLAG;
if (a == value) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
if ((a & 0xF) < (value & 0xF)) {
gb->registers[GB_REGISTER_AF] |= GB_HALF_CARRY_FLAG;
}
if (a < value) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
}
static void sbc_a_d8(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t value, a, carry;
GB_advance_cycles(gb, 4);
value = GB_read_memory(gb, gb->pc++);
GB_advance_cycles(gb, 4);
a = gb->registers[GB_REGISTER_AF] >> 8;
carry = (gb->registers[GB_REGISTER_AF] & GB_CARRY_FLAG) != 0;
gb->registers[GB_REGISTER_AF] = ((a - value - carry) << 8) | GB_SUBSTRACT_FLAG;
if ((uint8_t) (a - value - carry) == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
if ((a & 0xF) < (value & 0xF) + carry) {
gb->registers[GB_REGISTER_AF] |= GB_HALF_CARRY_FLAG;
}
if (((unsigned long) a) - ((unsigned long) value) - carry > 0xFF) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
}
static void and_a_d8(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t value, a;
GB_advance_cycles(gb, 4);
value = GB_read_memory(gb, gb->pc++);
GB_advance_cycles(gb, 4);
a = gb->registers[GB_REGISTER_AF] >> 8;
gb->registers[GB_REGISTER_AF] = ((a & value) << 8) | GB_HALF_CARRY_FLAG;
if ((a & value) == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
}
static void xor_a_d8(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t value, a;
GB_advance_cycles(gb, 4);
value = GB_read_memory(gb, gb->pc++);
GB_advance_cycles(gb, 4);
a = gb->registers[GB_REGISTER_AF] >> 8;
gb->registers[GB_REGISTER_AF] = (a ^ value) << 8;
if ((a ^ value) == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
}
static void or_a_d8(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t value, a;
GB_advance_cycles(gb, 4);
value = GB_read_memory(gb, gb->pc++);
GB_advance_cycles(gb, 4);
a = gb->registers[GB_REGISTER_AF] >> 8;
gb->registers[GB_REGISTER_AF] = (a | value) << 8;
if ((a | value) == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
}
static void cp_a_d8(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t value, a;
GB_advance_cycles(gb, 4);
value = GB_read_memory(gb, gb->pc++);
GB_advance_cycles(gb, 4);
a = gb->registers[GB_REGISTER_AF] >> 8;
gb->registers[GB_REGISTER_AF] &= 0xFF00;
gb->registers[GB_REGISTER_AF] |= GB_SUBSTRACT_FLAG;
if (a == value) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
if ((a & 0xF) < (value & 0xF)) {
gb->registers[GB_REGISTER_AF] |= GB_HALF_CARRY_FLAG;
}
if (a < value) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
}
static void rst(GB_gameboy_t *gb, uint8_t opcode)
{
uint16_t call_addr = gb->pc - 1;
GB_advance_cycles(gb, 8);
gb->registers[GB_REGISTER_SP] -= 2;
GB_write_memory(gb, gb->registers[GB_REGISTER_SP] + 1, (gb->pc) >> 8);
GB_advance_cycles(gb, 4);
GB_write_memory(gb, gb->registers[GB_REGISTER_SP], (gb->pc) & 0xFF);
GB_advance_cycles(gb, 4);
gb->pc = opcode ^ 0xC7;
GB_debugger_call_hook(gb, call_addr);
}
static void ret(GB_gameboy_t *gb, uint8_t opcode)
{
GB_debugger_ret_hook(gb);
GB_advance_cycles(gb, 4);
gb->pc = GB_read_memory(gb, gb->registers[GB_REGISTER_SP]);
GB_advance_cycles(gb, 4);
gb->pc |= GB_read_memory(gb, gb->registers[GB_REGISTER_SP] + 1) << 8;
GB_advance_cycles(gb, 8);
gb->registers[GB_REGISTER_SP] += 2;
}
static void reti(GB_gameboy_t *gb, uint8_t opcode)
{
ret(gb, opcode);
gb->ime = true;
}
static void call_a16(GB_gameboy_t *gb, uint8_t opcode)
{
uint16_t call_addr = gb->pc - 1;
GB_advance_cycles(gb, 4);
gb->registers[GB_REGISTER_SP] -= 2;
uint16_t addr = GB_read_memory(gb, gb->pc++);
GB_advance_cycles(gb, 4);
addr |= (GB_read_memory(gb, gb->pc++) << 8);
GB_advance_cycles(gb, 8);
GB_write_memory(gb, gb->registers[GB_REGISTER_SP] + 1, (gb->pc) >> 8);
GB_advance_cycles(gb, 4);
GB_write_memory(gb, gb->registers[GB_REGISTER_SP], (gb->pc) & 0xFF);
GB_advance_cycles(gb, 4);
gb->pc = addr;
GB_debugger_call_hook(gb, call_addr);
}
static void ld_da8_a(GB_gameboy_t *gb, uint8_t opcode)
{
GB_advance_cycles(gb, 4);
uint8_t temp = GB_read_memory(gb, gb->pc++);
GB_advance_cycles(gb, 4);
GB_write_memory(gb, 0xFF00 + temp, gb->registers[GB_REGISTER_AF] >> 8);
GB_advance_cycles(gb, 4);
}
static void ld_a_da8(GB_gameboy_t *gb, uint8_t opcode)
{
GB_advance_cycles(gb, 4);
gb->registers[GB_REGISTER_AF] &= 0xFF;
uint8_t temp = GB_read_memory(gb, gb->pc++);
GB_advance_cycles(gb, 4);
gb->registers[GB_REGISTER_AF] |= GB_read_memory(gb, 0xFF00 + temp) << 8;
GB_advance_cycles(gb, 4);
}
static void ld_dc_a(GB_gameboy_t *gb, uint8_t opcode)
{
GB_advance_cycles(gb, 4);
GB_write_memory(gb, 0xFF00 + (gb->registers[GB_REGISTER_BC] & 0xFF), gb->registers[GB_REGISTER_AF] >> 8);
GB_advance_cycles(gb, 4);
}
static void ld_a_dc(GB_gameboy_t *gb, uint8_t opcode)
{
GB_advance_cycles(gb, 4);
gb->registers[GB_REGISTER_AF] &= 0xFF;
gb->registers[GB_REGISTER_AF] |= GB_read_memory(gb, 0xFF00 + (gb->registers[GB_REGISTER_BC] & 0xFF)) << 8;
GB_advance_cycles(gb, 4);
}
static void add_sp_r8(GB_gameboy_t *gb, uint8_t opcode)
{
int16_t offset;
uint16_t sp = gb->registers[GB_REGISTER_SP];
GB_advance_cycles(gb, 4);
offset = (int8_t) GB_read_memory(gb, gb->pc++);
GB_advance_cycles(gb, 12);
gb->registers[GB_REGISTER_SP] += offset;
gb->registers[GB_REGISTER_AF] &= 0xFF00;
/* A new instruction, a new meaning for Half Carry! */
if ((sp & 0xF) + (offset & 0xF) > 0xF) {
gb->registers[GB_REGISTER_AF] |= GB_HALF_CARRY_FLAG;
}
if ((sp & 0xFF) + (offset & 0xFF) > 0xFF) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
}
static void jp_hl(GB_gameboy_t *gb, uint8_t opcode)
{
GB_advance_cycles(gb, 4);
gb->pc = gb->registers[GB_REGISTER_HL];
}
static void ld_da16_a(GB_gameboy_t *gb, uint8_t opcode)
{
uint16_t addr;
GB_advance_cycles(gb, 4);
addr = GB_read_memory(gb, gb->pc++);
GB_advance_cycles(gb, 4);
addr |= GB_read_memory(gb, gb->pc++) << 8;
GB_advance_cycles(gb, 4);
GB_write_memory(gb, addr, gb->registers[GB_REGISTER_AF] >> 8);
GB_advance_cycles(gb, 4);
}
static void ld_a_da16(GB_gameboy_t *gb, uint8_t opcode)
{
uint16_t addr;
GB_advance_cycles(gb, 4);
gb->registers[GB_REGISTER_AF] &= 0xFF;
addr = GB_read_memory(gb, gb->pc++);
GB_advance_cycles(gb, 4);
addr |= GB_read_memory(gb, gb->pc++) << 8 ;
GB_advance_cycles(gb, 4);
gb->registers[GB_REGISTER_AF] |= GB_read_memory(gb, addr) << 8;
GB_advance_cycles(gb, 4);
}
static void di(GB_gameboy_t *gb, uint8_t opcode)
{
/* DI is NOT delayed, not even on a CGB. Mooneye's di_timing-GS test fails on a CGB
for different reasons. */
GB_advance_cycles(gb, 4);
gb->ime = false;
}
static void ei(GB_gameboy_t *gb, uint8_t opcode)
{
/* ei is actually "disable interrupts for one instruction, then enable them". */
GB_advance_cycles(gb, 4);
if (!gb->ime && !gb->ime_toggle) {
gb->ime_toggle = true;
}
}
static void ld_hl_sp_r8(GB_gameboy_t *gb, uint8_t opcode)
{
int16_t offset;
GB_advance_cycles(gb, 4);
gb->registers[GB_REGISTER_AF] &= 0xFF00;
offset = (int8_t) GB_read_memory(gb, gb->pc++);
GB_advance_cycles(gb, 8);
gb->registers[GB_REGISTER_HL] = gb->registers[GB_REGISTER_SP] + offset;
if ((gb->registers[GB_REGISTER_SP] & 0xF) + (offset & 0xF) > 0xF) {
gb->registers[GB_REGISTER_AF] |= GB_HALF_CARRY_FLAG;
}
if ((gb->registers[GB_REGISTER_SP] & 0xFF) + (offset & 0xFF) > 0xFF) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
}
static void ld_sp_hl(GB_gameboy_t *gb, uint8_t opcode)
{
GB_advance_cycles(gb, 8);
gb->registers[GB_REGISTER_SP] = gb->registers[GB_REGISTER_HL];
}
static void rlc_r(GB_gameboy_t *gb, uint8_t opcode)
{
bool carry;
uint8_t value;
GB_advance_cycles(gb, 4);
value = get_src_value(gb, opcode);
carry = (value & 0x80) != 0;
gb->registers[GB_REGISTER_AF] &= 0xFF00;
set_src_value(gb, opcode, (value << 1) | carry);
if (carry) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
if (!(value << 1)) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
}
static void rrc_r(GB_gameboy_t *gb, uint8_t opcode)
{
bool carry;
uint8_t value;
GB_advance_cycles(gb, 4);
value = get_src_value(gb, opcode);
carry = (value & 0x01) != 0;
gb->registers[GB_REGISTER_AF] &= 0xFF00;
value = (value >> 1) | (carry << 7);
set_src_value(gb, opcode, value);
if (carry) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
if (value == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
}
static void rl_r(GB_gameboy_t *gb, uint8_t opcode)
{
bool carry;
uint8_t value;
bool bit7;
GB_advance_cycles(gb, 4);
value = get_src_value(gb, opcode);
carry = (gb->registers[GB_REGISTER_AF] & GB_CARRY_FLAG) != 0;
bit7 = (value & 0x80) != 0;
gb->registers[GB_REGISTER_AF] &= 0xFF00;
value = (value << 1) | carry;
set_src_value(gb, opcode, value);
if (bit7) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
if (value == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
}
static void rr_r(GB_gameboy_t *gb, uint8_t opcode)
{
bool carry;
uint8_t value;
bool bit1;
GB_advance_cycles(gb, 4);
value = get_src_value(gb, opcode);
carry = (gb->registers[GB_REGISTER_AF] & GB_CARRY_FLAG) != 0;
bit1 = (value & 0x1) != 0;
gb->registers[GB_REGISTER_AF] &= 0xFF00;
value = (value >> 1) | (carry << 7);
set_src_value(gb, opcode, value);
if (bit1) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
if (value == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
}
static void sla_r(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t value;
bool carry;
GB_advance_cycles(gb, 4);
value = get_src_value(gb, opcode);
carry = (value & 0x80) != 0;
gb->registers[GB_REGISTER_AF] &= 0xFF00;
set_src_value(gb, opcode, (value << 1));
if (carry) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
if ((value & 0x7F) == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
}
static void sra_r(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t bit7;
uint8_t value;
GB_advance_cycles(gb, 4);
value = get_src_value(gb, opcode);
bit7 = value & 0x80;
gb->registers[GB_REGISTER_AF] &= 0xFF00;
if (value & 1) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
value = (value >> 1) | bit7;
set_src_value(gb, opcode, value);
if (value == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
}
static void srl_r(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t value;
GB_advance_cycles(gb, 4);
value = get_src_value(gb, opcode);
gb->registers[GB_REGISTER_AF] &= 0xFF00;
set_src_value(gb, opcode, (value >> 1));
if (value & 1) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
if (!(value >> 1)) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
}
static void swap_r(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t value;
GB_advance_cycles(gb, 4);
value = get_src_value(gb, opcode);
gb->registers[GB_REGISTER_AF] &= 0xFF00;
set_src_value(gb, opcode, (value >> 4) | (value << 4));
if (!value) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
}
static void bit_r(GB_gameboy_t *gb, uint8_t opcode)
{
uint8_t value;
uint8_t bit;
GB_advance_cycles(gb, 4);
value = get_src_value(gb, opcode);
bit = 1 << ((opcode >> 3) & 7);
if ((opcode & 0xC0) == 0x40) { /* Bit */
gb->registers[GB_REGISTER_AF] &= 0xFF00 | GB_CARRY_FLAG;
gb->registers[GB_REGISTER_AF] |= GB_HALF_CARRY_FLAG;
if (!(bit & value)) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
}
}
else if ((opcode & 0xC0) == 0x80) { /* res */
set_src_value(gb, opcode, value & ~bit) ;
}
else if ((opcode & 0xC0) == 0xC0) { /* set */
set_src_value(gb, opcode, value | bit) ;
}
}
static void cb_prefix(GB_gameboy_t *gb, uint8_t opcode)
{
GB_advance_cycles(gb, 4);
opcode = GB_read_memory(gb, gb->pc++);
switch (opcode >> 3) {
case 0:
rlc_r(gb, opcode);
break;
case 1:
rrc_r(gb, opcode);
break;
case 2:
rl_r(gb, opcode);
break;
case 3:
rr_r(gb, opcode);
break;
case 4:
sla_r(gb, opcode);
break;
case 5:
sra_r(gb, opcode);
break;
case 6:
swap_r(gb, opcode);
break;
case 7:
srl_r(gb, opcode);
break;
default:
bit_r(gb, opcode);
break;
}
}
static GB_opcode_t *opcodes[256] = {
/* X0 X1 X2 X3 X4 X5 X6 X7 */
/* X8 X9 Xa Xb Xc Xd Xe Xf */
nop, ld_rr_d16, ld_drr_a, inc_rr, inc_hr, dec_hr, ld_hr_d8, rlca, /* 0X */
ld_da16_sp, add_hl_rr, ld_a_drr, dec_rr, inc_lr, dec_lr, ld_lr_d8, rrca,
stop, ld_rr_d16, ld_drr_a, inc_rr, inc_hr, dec_hr, ld_hr_d8, rla, /* 1X */
jr_r8, add_hl_rr, ld_a_drr, dec_rr, inc_lr, dec_lr, ld_lr_d8, rra,
jr_cc_r8, ld_rr_d16, ld_dhli_a, inc_rr, inc_hr, dec_hr, ld_hr_d8, daa, /* 2X */
jr_cc_r8, add_hl_rr, ld_a_dhli, dec_rr, inc_lr, dec_lr, ld_lr_d8, cpl,
jr_cc_r8, ld_rr_d16, ld_dhld_a, inc_rr, inc_dhl, dec_dhl, ld_dhl_d8, scf, /* 3X */
jr_cc_r8, add_hl_rr, ld_a_dhld, dec_rr, inc_hr, dec_hr, ld_hr_d8, ccf,
nop, ld_b_c, ld_b_d, ld_b_e, ld_b_h, ld_b_l, ld_b_dhl, ld_b_a, /* 4X */
ld_c_b, nop, ld_c_d, ld_c_e, ld_c_h, ld_c_l, ld_c_dhl, ld_c_a,
ld_d_b, ld_d_c, nop, ld_d_e, ld_d_h, ld_d_l, ld_d_dhl, ld_d_a, /* 5X */
ld_e_b, ld_e_c, ld_e_d, nop, ld_e_h, ld_e_l, ld_e_dhl, ld_e_a,
ld_h_b, ld_h_c, ld_h_d, ld_h_e, nop, ld_h_l, ld_h_dhl, ld_h_a, /* 6X */
ld_l_b, ld_l_c, ld_l_d, ld_l_e, ld_l_h, nop, ld_l_dhl, ld_l_a,
ld_dhl_b, ld_dhl_c, ld_dhl_d, ld_dhl_e, ld_dhl_h, ld_dhl_l, halt, ld_dhl_a, /* 7X */
ld_a_b, ld_a_c, ld_a_d, ld_a_e, ld_a_h, ld_a_l, ld_a_dhl, nop,
add_a_r, add_a_r, add_a_r, add_a_r, add_a_r, add_a_r, add_a_r, add_a_r, /* 8X */
adc_a_r, adc_a_r, adc_a_r, adc_a_r, adc_a_r, adc_a_r, adc_a_r, adc_a_r,
sub_a_r, sub_a_r, sub_a_r, sub_a_r, sub_a_r, sub_a_r, sub_a_r, sub_a_r, /* 9X */
sbc_a_r, sbc_a_r, sbc_a_r, sbc_a_r, sbc_a_r, sbc_a_r, sbc_a_r, sbc_a_r,
and_a_r, and_a_r, and_a_r, and_a_r, and_a_r, and_a_r, and_a_r, and_a_r, /* aX */
xor_a_r, xor_a_r, xor_a_r, xor_a_r, xor_a_r, xor_a_r, xor_a_r, xor_a_r,
or_a_r, or_a_r, or_a_r, or_a_r, or_a_r, or_a_r, or_a_r, or_a_r, /* bX */
cp_a_r, cp_a_r, cp_a_r, cp_a_r, cp_a_r, cp_a_r, cp_a_r, cp_a_r,
ret_cc, pop_rr, jp_cc_a16, jp_a16, call_cc_a16,push_rr, add_a_d8, rst, /* cX */
ret_cc, ret, jp_cc_a16, cb_prefix, call_cc_a16,call_a16, adc_a_d8, rst,
ret_cc, pop_rr, jp_cc_a16, ill, call_cc_a16,push_rr, sub_a_d8, rst, /* dX */
ret_cc, reti, jp_cc_a16, ill, call_cc_a16,ill, sbc_a_d8, rst,
ld_da8_a, pop_rr, ld_dc_a, ill, ill, push_rr, and_a_d8, rst, /* eX */
add_sp_r8, jp_hl, ld_da16_a, ill, ill, ill, xor_a_d8, rst,
ld_a_da8, pop_rr, ld_a_dc, di, ill, push_rr, or_a_d8, rst, /* fX */
ld_hl_sp_r8,ld_sp_hl, ld_a_da16, ei, ill, ill, cp_a_d8, rst,
};
void GB_cpu_run(GB_gameboy_t *gb)
{
if (gb->hdma_on) {
GB_advance_cycles(gb, 4);
return;
}
gb->vblank_just_occured = false;
if (gb->halted) {
gb->display_hack = 1;
GB_advance_cycles(gb, 2);
}
uint8_t interrupt_queue = gb->interrupt_enable & gb->io_registers[GB_IO_IF] & 0x1F;
if (gb->halted) {
gb->display_hack = 2;
GB_advance_cycles(gb, 2);
gb->display_hack = 0;
}
gb->io_registers[GB_IO_IF] |= gb->future_interrupts;
gb->future_interrupts = 0;
bool effecitve_ime = gb->ime;
if (gb->ime_toggle) {
gb->ime = !gb->ime;
gb->ime_toggle = false;
}
/* Wake up from HALT mode without calling interrupt code. */
if (gb->halted && !effecitve_ime && interrupt_queue) {
gb->halted = false;
}
/* Call interrupt */
else if (effecitve_ime && interrupt_queue) {
gb->halted = false;
uint16_t call_addr = gb->pc - 1;
GB_advance_cycles(gb, 12);
gb->registers[GB_REGISTER_SP] -= 2;
GB_write_memory(gb, gb->registers[GB_REGISTER_SP] + 1, (gb->pc) >> 8);
interrupt_queue = gb->interrupt_enable;
GB_advance_cycles(gb, 4);
GB_write_memory(gb, gb->registers[GB_REGISTER_SP], (gb->pc) & 0xFF);
interrupt_queue &= (gb->io_registers[GB_IO_IF] | gb->future_interrupts) & 0x1F;
gb->io_registers[GB_IO_IF] |= gb->future_interrupts;
gb->future_interrupts = 0;
GB_advance_cycles(gb, 4);
if (interrupt_queue) {
uint8_t interrupt_bit = 0;
while (!(interrupt_queue & 1)) {
interrupt_queue >>= 1;
interrupt_bit++;
}
gb->io_registers[GB_IO_IF] &= ~(1 << interrupt_bit);
gb->pc = interrupt_bit * 8 + 0x40;
}
else {
gb->pc = 0;
}
gb->ime = false;
GB_debugger_call_hook(gb, call_addr);
}
/* Run mode */
else if(!gb->halted && !gb->stopped) {
uint8_t opcode = GB_read_memory(gb, gb->pc++);
if (gb->halt_bug) {
gb->pc--;
gb->halt_bug = false;
}
opcodes[opcode](gb, opcode);
}
}
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