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Rework pipelining implementation
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The shell is finally booting!
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@allkern
allkern committed Jul 4, 2023
1 parent a034f22 commit 61c23fa
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Showing 11 changed files with 128 additions and 115 deletions.
167 changes: 77 additions & 90 deletions psx/cpu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -84,15 +84,15 @@ uint32_t g_psx_cpu_cop0_write_mask_table[] = {
0x00000000 // cop0r15 - PRID - Processor ID (R)
};

#define OP ((cpu->buf[1] >> 26) & 0x3f)
#define S ((cpu->buf[1] >> 21) & 0x1f)
#define T ((cpu->buf[1] >> 16) & 0x1f)
#define D ((cpu->buf[1] >> 11) & 0x1f)
#define IMM5 ((cpu->buf[1] >> 6) & 0x1f)
#define CMT ((cpu->buf[1] >> 6) & 0xfffff)
#define SOP (cpu->buf[1] & 0x3f)
#define IMM26 (cpu->buf[1] & 0x3ffffff)
#define IMM16 (cpu->buf[1] & 0xffff)
#define OP ((cpu->opcode >> 26) & 0x3f)
#define S ((cpu->opcode >> 21) & 0x1f)
#define T ((cpu->opcode >> 16) & 0x1f)
#define D ((cpu->opcode >> 11) & 0x1f)
#define IMM5 ((cpu->opcode >> 6) & 0x1f)
#define CMT ((cpu->opcode >> 6) & 0xfffff)
#define SOP (cpu->opcode & 0x3f)
#define IMM26 (cpu->opcode & 0x3ffffff)
#define IMM16 (cpu->opcode & 0xffff)
#define IMM16S ((int32_t)((int16_t)IMM16))

#define R_R0 (cpu->r[0])
Expand Down Expand Up @@ -128,7 +128,7 @@ uint32_t g_psx_cpu_cop0_write_mask_table[] = {
#define R_FP (cpu->r[30])
#define R_RA (cpu->r[31])

// #define CPU_TRACE
#define CPU_TRACE

#ifdef CPU_TRACE
#define TRACE_M(m) \
Expand Down Expand Up @@ -210,6 +210,12 @@ uint32_t g_psx_cpu_cop0_write_mask_table[] = {
#define SE8(v) ((int32_t)((int8_t)v))
#define SE16(v) ((int32_t)((int16_t)v))

#define BRANCH(offset) \
cpu->next_pc = cpu->next_pc + (offset); \
cpu->next_pc = cpu->next_pc - 4; \
cpu->branch = 1; \
cpu->branch_taken = 1;

const char* g_mips_cop0_register_names[] = {
"cop0_r0",
"cop0_r1",
Expand Down Expand Up @@ -288,28 +294,13 @@ void cpu_a_kcall_hook(psx_cpu_t*);
void cpu_b_kcall_hook(psx_cpu_t*);

void psx_cpu_fetch(psx_cpu_t* cpu) {
cpu->buf[0] = psx_bus_read32(cpu->bus, cpu->pc);
cpu->pc += 4;
//cpu->buf[0] = psx_bus_read32(cpu->bus, cpu->pc);
//cpu->pc += 4;

// Discard fetch cycles
psx_bus_get_access_cycles(cpu->bus);
}

void psx_cpu_init(psx_cpu_t* cpu, psx_bus_t* bus) {
memset(cpu, 0, sizeof(psx_cpu_t));

psx_cpu_set_a_kcall_hook(cpu, cpu_a_kcall_hook);
psx_cpu_set_b_kcall_hook(cpu, cpu_b_kcall_hook);

cpu->bus = bus;
cpu->pc = 0xbfc00000;

cpu->cop0_r[COP0_SR] = 0x10900000;
cpu->cop0_r[COP0_PRID] = 0x00000002;

psx_cpu_fetch(cpu);
}

void psx_cpu_destroy(psx_cpu_t* cpu) {
free(cpu);
}
Expand All @@ -330,28 +321,43 @@ void psx_cpu_load_state(psx_cpu_t* cpu, FILE* file) {
fread((char*)cpu, sizeof(*cpu) - sizeof(psx_bus_t*), 1, file);
}

void psx_cpu_cycle(psx_cpu_t* cpu) {
if ((cpu->pc & 0x3fffffff) == 0x000000a4)
if (cpu->a_function_hook) cpu->a_function_hook(cpu);
void psx_cpu_init(psx_cpu_t* cpu, psx_bus_t* bus) {
memset(cpu, 0, sizeof(psx_cpu_t));

psx_cpu_set_a_kcall_hook(cpu, cpu_a_kcall_hook);
psx_cpu_set_b_kcall_hook(cpu, cpu_b_kcall_hook);

cpu->bus = bus;
cpu->pc = 0xbfc00000;
cpu->next_pc = cpu->pc + 4;

cpu->cop0_r[COP0_SR] = 0x10900000;
cpu->cop0_r[COP0_PRID] = 0x00000002;
}

void psx_cpu_cycle(psx_cpu_t* cpu) {
if ((cpu->pc & 0x3fffffff) == 0x000000b4)
if (cpu->a_function_hook) cpu->b_function_hook(cpu);
if (cpu->b_function_hook) cpu->b_function_hook(cpu);

cpu->buf[1] = cpu->buf[0];
cpu->saved_pc = cpu->pc;
cpu->delay_slot = cpu->branch;
cpu->branch = 0;
cpu->branch_taken = 0;

if (cpu->pc & 0x3) {
if (cpu->saved_pc & 3) {
psx_cpu_exception(cpu, CAUSE_ADEL);

return;
}

if (psx_cpu_check_irq(cpu))
return;
cpu->opcode = psx_bus_read32(cpu->bus, cpu->pc);

psx_cpu_fetch(cpu);
cpu->pc = cpu->next_pc;
cpu->next_pc += 4;

cpu->delay_slot = cpu->branch;
cpu->branch = 0;
if (psx_cpu_check_irq(cpu)) {
psx_cpu_exception(cpu, CAUSE_INT);

return;
}

g_psx_cpu_primary_table[OP](cpu);

Expand All @@ -362,33 +368,25 @@ void psx_cpu_cycle(psx_cpu_t* cpu) {
}

int psx_cpu_check_irq(psx_cpu_t* cpu) {
if ((cpu->cop0_r[COP0_SR] & SR_IEC) && (cpu->cop0_r[COP0_SR] & cpu->cop0_r[COP0_CAUSE] & 0x00000700)) {
psx_cpu_exception(cpu, CAUSE_INT);

return 1;
}

return 0;
return (cpu->cop0_r[COP0_SR] & SR_IEC) && (cpu->cop0_r[COP0_SR] & cpu->cop0_r[COP0_CAUSE] & 0x00000700);
}

void psx_cpu_exception(psx_cpu_t* cpu, uint32_t cause) {
cpu->cop0_r[COP0_CAUSE] &= 0x0000ff00;

// Set excode and clear 3 LSBs
cpu->cop0_r[COP0_CAUSE] &= 0xffffff80;
cpu->cop0_r[COP0_CAUSE] |= cause;

if (cause == CAUSE_INT) {
cpu->cop0_r[COP0_EPC] = cpu->pc - 4;
} else {
cpu->cop0_r[COP0_EPC] = cpu->pc - 8;
}
cpu->cop0_r[COP0_EPC] = cpu->saved_pc;

// If we're in a delay slot, set delay slot bit
// on CAUSE
if (cpu->delay_slot) {
cpu->cop0_r[COP0_EPC] -= 4;
cpu->cop0_r[COP0_CAUSE] |= 0x80000000;
} else {
cpu->cop0_r[COP0_CAUSE] &= 0x7fffffff;
}

if ((cause == CAUSE_INT) && (cpu->cop0_r[COP0_EPC] & 0xfe000000) == 0x4a000000) {
cpu->cop0_r[COP0_EPC] += 4;
}

// Do exception stack push
Expand All @@ -399,21 +397,15 @@ void psx_cpu_exception(psx_cpu_t* cpu, uint32_t cause) {

// Set PC to the vector selected on BEV
cpu->pc = (cpu->cop0_r[COP0_SR] & SR_BEV) ? 0xbfc00180 : 0x80000080;

// Simulate pipeline flush
psx_cpu_fetch(cpu);

cpu->buf[1] = cpu->buf[0];
cpu->next_pc = cpu->pc + 4;
}

void psx_cpu_irq(psx_cpu_t* cpu, uint32_t irq) {
// Set interrupt pending field
cpu->cop0_r[COP0_CAUSE] &= ~SR_IM2;
cpu->cop0_r[COP0_CAUSE] |= irq ? SR_IM2 : 0;
}

void psx_cpu_i_invalid(psx_cpu_t* cpu) {
log_fatal("%08x: Illegal instruction %08x", cpu->pc - 8, cpu->buf[1]);
log_fatal("%08x: Illegal instruction %08x", cpu->pc - 8, cpu->opcode);

psx_cpu_exception(cpu, CAUSE_RI);
}
Expand All @@ -425,6 +417,7 @@ void psx_cpu_i_special(psx_cpu_t* cpu) {

void psx_cpu_i_bxx(psx_cpu_t* cpu) {
cpu->branch = 1;
cpu->branch_taken = 0;

g_psx_cpu_bxx_table[T](cpu);
}
Expand All @@ -438,8 +431,7 @@ void psx_cpu_i_bltz(psx_cpu_t* cpu) {
DO_PENDING_LOAD;

if ((int32_t)s < (int32_t)0) {
cpu->pc -= 4;
cpu->pc += (IMM16S << 2);
BRANCH(IMM16S << 2);
}
}

Expand All @@ -451,8 +443,7 @@ void psx_cpu_i_bgez(psx_cpu_t* cpu) {
DO_PENDING_LOAD;

if ((int32_t)s >= (int32_t)0) {
cpu->pc -= 4;
cpu->pc += (IMM16S << 2);
BRANCH(IMM16S << 2);
}
}

Expand All @@ -463,11 +454,10 @@ void psx_cpu_i_bltzal(psx_cpu_t* cpu) {

DO_PENDING_LOAD;

R_RA = cpu->pc;
R_RA = cpu->next_pc;

if ((int32_t)s < (int32_t)0) {
cpu->pc -= 4;
cpu->pc += (IMM16S << 2);
BRANCH(IMM16S << 2);
}
}

Expand All @@ -478,11 +468,10 @@ void psx_cpu_i_bgezal(psx_cpu_t* cpu) {

DO_PENDING_LOAD;

R_RA = cpu->pc;
R_RA = cpu->next_pc;

if ((int32_t)s >= (int32_t)0) {
cpu->pc -= 4;
cpu->pc += (IMM16S << 2);
BRANCH(IMM16S << 2);
}
}

Expand All @@ -493,7 +482,7 @@ void psx_cpu_i_j(psx_cpu_t* cpu) {

DO_PENDING_LOAD;

cpu->pc = (cpu->pc & 0xf0000000) | (IMM26 << 2);
cpu->next_pc = (cpu->next_pc & 0xf0000000) | (IMM26 << 2);
}

void psx_cpu_i_jal(psx_cpu_t* cpu) {
Expand All @@ -503,13 +492,14 @@ void psx_cpu_i_jal(psx_cpu_t* cpu) {

DO_PENDING_LOAD;

cpu->r[31] = cpu->pc;
R_RA = cpu->next_pc;

cpu->pc = (cpu->pc & 0xf0000000) | (IMM26 << 2);
cpu->next_pc = (cpu->next_pc & 0xf0000000) | (IMM26 << 2);
}

void psx_cpu_i_beq(psx_cpu_t* cpu) {
cpu->branch = 1;
cpu->branch_taken = 0;

TRACE_B("beq");

Expand All @@ -519,13 +509,13 @@ void psx_cpu_i_beq(psx_cpu_t* cpu) {
DO_PENDING_LOAD;

if (s == t) {
cpu->pc -= 4;
cpu->pc += (IMM16S << 2);
BRANCH(IMM16S << 2);
}
}

void psx_cpu_i_bne(psx_cpu_t* cpu) {
cpu->branch = 1;
cpu->branch_taken = 0;

TRACE_B("bne");

Expand All @@ -535,13 +525,13 @@ void psx_cpu_i_bne(psx_cpu_t* cpu) {
DO_PENDING_LOAD;

if (s != t) {
cpu->pc -= 4;
cpu->pc += (IMM16S << 2);
BRANCH(IMM16S << 2);
}
}

void psx_cpu_i_blez(psx_cpu_t* cpu) {
cpu->branch = 1;
cpu->branch_taken = 0;

TRACE_B("blez");

Expand All @@ -550,13 +540,13 @@ void psx_cpu_i_blez(psx_cpu_t* cpu) {
DO_PENDING_LOAD;

if ((int32_t)s <= (int32_t)0) {
cpu->pc -= 4;
cpu->pc += (IMM16S << 2);
BRANCH(IMM16S << 2);
}
}

void psx_cpu_i_bgtz(psx_cpu_t* cpu) {
cpu->branch = 1;
cpu->branch_taken = 0;

TRACE_B("bgtz");

Expand All @@ -565,8 +555,7 @@ void psx_cpu_i_bgtz(psx_cpu_t* cpu) {
DO_PENDING_LOAD;

if ((int32_t)s > (int32_t)0) {
cpu->pc -= 4;
cpu->pc += (IMM16S << 2);
BRANCH(IMM16S << 2);
}
}

Expand Down Expand Up @@ -1002,7 +991,7 @@ void psx_cpu_i_jr(psx_cpu_t* cpu) {

DO_PENDING_LOAD;

cpu->pc = s;
cpu->next_pc = s;
}

void psx_cpu_i_jalr(psx_cpu_t* cpu) {
Expand All @@ -1014,15 +1003,13 @@ void psx_cpu_i_jalr(psx_cpu_t* cpu) {

DO_PENDING_LOAD;

cpu->r[D] = cpu->pc;
cpu->r[D] = cpu->next_pc;

cpu->pc = s;
cpu->next_pc = s;
}

void psx_cpu_i_syscall(psx_cpu_t* cpu) {
TRACE_I20("syscall");

//log_info("SYS(%02xh): %s()", cpu->r[4], g_psx_cpu_syscall_function_symbol_table[cpu->r[4]]);

DO_PENDING_LOAD;

Expand Down
6 changes: 3 additions & 3 deletions psx/cpu.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -66,13 +66,13 @@ typedef void (*psx_cpu_kcall_hook_t)(psx_cpu_t*);

struct psx_cpu_t {
uint32_t r[32];
uint32_t buf[2];
uint32_t pc;
uint32_t opcode;
uint32_t pc, next_pc, saved_pc;
uint32_t hi, lo;
uint32_t load_d, load_v;
uint32_t last_cycles;
uint32_t total_cycles;
int branch, delay_slot;
int branch, delay_slot, branch_taken;

uint32_t cop0_r[16];

Expand Down
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