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gb6
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fix a bunch of instructions, passes most blargg tests now

This commit is contained in:
Matthew Laux 2023-05-17 23:41:55 -05:00
parent b2a6890524
commit ead7a3e17c
4 changed files with 90 additions and 39 deletions
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91
src/cpu.c
View File

@ -73,13 +73,14 @@ static inline void write8(struct cpu *cpu, u16 address, u8 data)
static inline void write16(struct cpu *cpu, u16 address, u16 data)
{
dmg_write(cpu->dmg, address, data);
dmg_write(cpu->dmg, address, data & 0xff);
dmg_write(cpu->dmg, address + 1, data >> 8);
}
static void inc_with_carry(struct cpu *regs, u8 *reg)
{
clear_flag(regs, FLAG_SIGN);
if(*reg == 0xff || *reg == 0x0f)
if((*reg & 0xf) == 0xf)
set_flag(regs, FLAG_HALF_CARRY);
else clear_flag(regs, FLAG_HALF_CARRY);
(*reg)++;
@ -91,7 +92,7 @@ static void inc_with_carry(struct cpu *regs, u8 *reg)
static void dec_with_carry(struct cpu *regs, u8 *reg)
{
set_flag(regs, FLAG_SIGN);
if(*reg == 0x00 || *reg == 0x10)
if((*reg & 0xf) == 0)
set_flag(regs, FLAG_HALF_CARRY);
else clear_flag(regs, FLAG_HALF_CARRY);
(*reg)--;
@ -103,11 +104,20 @@ static void dec_with_carry(struct cpu *regs, u8 *reg)
static u8 rotate_left(struct cpu *regs, u8 reg)
{
int old_carry = flag_isset(regs, FLAG_CARRY);
// copy old leftmost bit to carry flag, clear Z, N, H
regs->f = (reg & 0x80) >> 3;
// rotate
int result = reg << 1 | old_carry;
if (!result) set_flag(regs, FLAG_ZERO);
int result = (u8) ((reg & 0x7f) << 1) | old_carry;
if (!result) {
set_flag(regs, FLAG_ZERO);
} else {
clear_flag(regs, FLAG_ZERO);
}
clear_flag(regs, FLAG_SIGN);
clear_flag(regs, FLAG_HALF_CARRY);
if (reg & 0x80) {
set_flag(regs, FLAG_CARRY);
} else {
clear_flag(regs, FLAG_CARRY);
}
return result;
}
@ -154,7 +164,7 @@ static u8 rrc(struct cpu *cpu, u8 val)
static u8 shift_left(struct cpu *cpu, u8 value)
{
int result = value << 1;
u8 result = value << 1;
if (result == 0) {
set_flag(cpu, FLAG_ZERO);
} else {
@ -172,7 +182,7 @@ static u8 shift_left(struct cpu *cpu, u8 value)
static u8 shift_right(struct cpu *cpu, u8 value)
{
int result = (signed) value >> 1;
u8 result = (signed char) value >> 1;
if (result == 0) {
set_flag(cpu, FLAG_ZERO);
} else {
@ -257,13 +267,9 @@ static void and(struct cpu *cpu, u8 value)
static void add(struct cpu *cpu, u8 value, int with_carry)
{
u8 sum_trunc;
int sum_full = cpu->a + value;
int carry = (with_carry && flag_isset(cpu, FLAG_CARRY)) ? 1 : 0;
if (carry) {
sum_full++;
}
sum_trunc = (u8) sum_full;
int sum_full = cpu->a + value + carry;
u8 sum_trunc = (u8) sum_full;
if (sum_trunc == 0) {
set_flag(cpu, FLAG_ZERO);
} else {
@ -285,25 +291,21 @@ static void add(struct cpu *cpu, u8 value, int with_carry)
static void subtract(struct cpu *cpu, u8 value, int with_carry, int just_compare)
{
u8 sum_trunc;
int sum_full = cpu->a - value;
int carry = (with_carry && flag_isset(cpu, FLAG_CARRY)) ? 1 : 0;
if (carry) {
sum_full--;
}
sum_trunc = (u8) sum_full;
int sum_full = cpu->a - value - carry;
u8 sum_trunc = (u8) sum_full;
if (!sum_trunc) {
set_flag(cpu, FLAG_ZERO);
} else {
clear_flag(cpu, FLAG_ZERO);
}
set_flag(cpu, FLAG_SIGN);
if (value > cpu->a) {
if (sum_full < 0) {
set_flag(cpu, FLAG_CARRY);
} else {
clear_flag(cpu, FLAG_CARRY);
}
if (((cpu->a & 0xf) - (value & 0xf)) & 0x10) {
if (((cpu->a & 0xf) - (value & 0xf) - carry) & 0x10) {
set_flag(cpu, FLAG_HALF_CARRY);
} else {
clear_flag(cpu, FLAG_HALF_CARRY);
@ -336,21 +338,22 @@ static u16 pop(struct cpu *cpu)
static void add16(struct cpu *cpu, u16 src)
{
clear_flag(cpu, FLAG_SIGN);
int total = read_hl(cpu) + src; // promoted to int
int trunc = total & 0xffff;
clear_flag(cpu, FLAG_SIGN);
if (total > 0xffff) {
set_flag(cpu, FLAG_CARRY);
} else {
clear_flag(cpu, FLAG_CARRY);
}
if (((cpu->h & 0xf) + ((src >> 8) & 0xf)) & 0x10) {
if (((read_hl(cpu) & 0xfff) + (src & 0xfff)) & 0x1000) {
// true if carry from bit 11 to bit 12
set_flag(cpu, FLAG_HALF_CARRY);
} else {
clear_flag(cpu, FLAG_HALF_CARRY);
}
write_hl(cpu, total & 0xffff);
write_hl(cpu, trunc);
}
static u8 read_reg(struct cpu *cpu, int index)
@ -407,6 +410,8 @@ static void extended_insn(struct cpu *cpu, u8 insn)
srl,
};
// rl, sla, sra
#ifdef GB6_DEBUG
printf(" %s\n", instructions[insn + 0x100].format);
#endif
@ -473,6 +478,24 @@ static void daa(struct cpu *cpu)
clear_flag(cpu, FLAG_HALF_CARRY);
}
static void scf(struct cpu *cpu)
{
clear_flag(cpu, FLAG_SIGN);
clear_flag(cpu, FLAG_HALF_CARRY);
set_flag(cpu, FLAG_CARRY);
}
static void ccf(struct cpu *cpu)
{
clear_flag(cpu, FLAG_SIGN);
clear_flag(cpu, FLAG_HALF_CARRY);
if (flag_isset(cpu, FLAG_CARRY)) {
clear_flag(cpu, FLAG_CARRY);
} else {
set_flag(cpu, FLAG_CARRY);
}
}
static u16 handlers[] = { 0x40, 0x48, 0x50, 0x58, 0x60 };
static u16 check_interrupts(struct cpu *cpu)
@ -508,10 +531,15 @@ void cpu_step(struct cpu *cpu)
intr_dest = check_interrupts(cpu);
if (intr_dest) {
push(cpu, cpu->pc);
cpu->halted = 0;
cpu->pc = intr_dest;
return;
}
if (cpu->halted) {
return;
}
u8 opc = dmg_read(cpu->dmg, cpu->pc);
#ifdef GB6_DEBUG
printf("0x%04x %s\n", cpu->pc, instructions[opc].format);
@ -531,6 +559,7 @@ void cpu_step(struct cpu *cpu)
break;
case 0x0f: // RRCA
cpu->a = rrc(cpu, cpu->a);
clear_flag(cpu, FLAG_ZERO);
break;
case 0x10: // STOP
cpu->pc++;
@ -541,6 +570,7 @@ void cpu_step(struct cpu *cpu)
break;
case 0x07: // RLCA
cpu->a = rlc(cpu, cpu->a);
clear_flag(cpu, FLAG_ZERO);
break;
case 0x08: // LD (a16),SP
write16(cpu, read16(cpu, cpu->pc), cpu->sp);
@ -554,16 +584,18 @@ void cpu_step(struct cpu *cpu)
break;
case 0x17: // RLA
cpu->a = rotate_left(cpu, cpu->a);
clear_flag(cpu, FLAG_ZERO);
break;
case 0x1f: // RRA
cpu->a = rotate_right(cpu, cpu->a);
clear_flag(cpu, FLAG_ZERO);
break;
case 0x37: // SCF
set_flag(cpu, FLAG_CARRY);
scf(cpu);
break;
case 0x3f: // CCF
clear_flag(cpu, FLAG_CARRY);
ccf(cpu);
break;
// incs and decs
@ -944,6 +976,7 @@ void cpu_step(struct cpu *cpu)
break;
case 0x76: // HALT
cpu->halted = 1;
break;
case 0xc1: // POP BC

2
src/cpu.h
View File

@ -20,6 +20,8 @@ struct cpu
u32 cycle_count;
u8 interrupt_enable;
u8 halted;
struct dmg *dmg;
// u8 (*mem_read)(void *, u16);
// void (*mem_write)(void *, u16, u8);

30
src/dmg.c
View File

@ -50,8 +50,6 @@ static u8 get_button_state(struct dmg *dmg)
return ret;
}
static int counter;
u8 dmg_read(void *_dmg, u16 address)
{
struct dmg *dmg = (struct dmg *) _dmg;
@ -82,8 +80,13 @@ u8 dmg_read(void *_dmg, u16 address)
} else if (address == 0xff00) {
return get_button_state(dmg);
} else if (address == REG_TIMER_DIV) {
counter++;
return counter;
return (dmg->timer_div & 0xff00) >> 8;
} else if (address == REG_TIMER_COUNT) {
return dmg->timer_count;
} else if (address == REG_TIMER_MOD) {
return dmg->timer_mod;
} else if (address == REG_TIMER_CONTROL) {
return dmg->timer_control;
} else if (address == 0xff0f) {
return dmg->interrupt_requested;
} else if (address == 0xffff) {
@ -116,6 +119,17 @@ void dmg_write(void *_dmg, u16 address, u8 data)
} else if (address < 0xe000) {
// printf("write ram %04x %02x\n", address, data);
dmg->main_ram[address - 0xc000] = data;
} else if (address == REG_TIMER_DIV) {
dmg->timer_div = 0;
} else if (address == REG_TIMER_COUNT) {
printf("write timer count\n");
dmg->timer_count = data;
} else if (address == REG_TIMER_MOD) {
printf("write timer mod\n");
dmg->timer_mod = data;
} else if (address == REG_TIMER_CONTROL) {
printf("write timer control\n");
dmg->timer_control = data;
} else if (address == 0xFF46) {
u16 src = data << 8;
int k = 0;
@ -248,15 +262,13 @@ static void render_objs(struct dmg *dmg)
static void timer_step(struct dmg *dmg)
{
dmg->timer_div++;
if (!(dmg_read(dmg, REG_TIMER_CONTROL) & TIMER_CONTROL_ENABLED)) {
return;
}
int passed = dmg->cpu->cycle_count - dmg->last_timer_update;
// TODO
if (passed < 10000) {
return;
}
u8 counter = dmg_read(dmg, REG_TIMER_COUNT);
u8 modulo = dmg_read(dmg, REG_TIMER_MOD);
@ -278,7 +290,7 @@ void dmg_step(void *_dmg)
// order of dependencies? i think cpu needs to step first then update
// all other hw
cpu_step(dmg->cpu);
// timer_step(dmg);
//timer_step(dmg);
// each line takes 456 cycles
int cycle_diff = dmg->cpu->cycle_count - dmg->last_lcd_update;

6
src/dmg.h
View File

@ -36,12 +36,16 @@ struct dmg {
u32 last_lcd_update;
u32 last_timer_update;
int joypad_selected;
int action_selected; // non-0 if A/B/start/select selected, 0 for directions
int action_selected;
u8 interrupt_enabled;
u8 interrupt_requested;
u8 joypad;
u8 action_buttons;
u16 timer_div;
u8 timer_count;
u8 timer_mod;
u8 timer_control;
};
void dmg_new(struct dmg *dmg, struct cpu *cpu, struct rom *rom, struct lcd *lcd);