BRNSystems/RISC-B
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Do some stuff

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This commit is contained in:
Bruno Rybársky
2025-02-05 20:32:36 +01:00
parent 2daec68484
commit 9837729656
7 changed files with 630 additions and 396 deletions
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52
cpu/memory.c
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@@ -37,8 +37,8 @@ uint32_t read_mem32(CPU *cpu, uint32_t addr) {
return read_mem16(cpu, addr) | (read_mem16(cpu, addr + 2) << 16);
}
uint32_t read_address(CPU *cpu) {
uint32_t out = read_mem16(cpu, cpu->pc) | (read_mem16(cpu, cpu->pc + 2) << 16);
uint32_t read_address_argument(CPU *cpu) {
uint32_t out = read_mem32(cpu, cpu->pc);
cpu->pc += 4;
if (out >= MEM_SIZE) {
out = MEM_SIZE - 1;
@@ -46,6 +46,54 @@ uint32_t read_address(CPU *cpu) {
return out;
}
// Push a 32-bit program counter (PC) onto the stack
void write_stack(CPU *cpu) {
if (cpu->pc >= MEM_SIZE) {
return; // Invalid memory address
}
if (cpu->stack_ptr >= STACK_SIZE - 1) {
return; // Stack overflow protection
}
cpu->stack[++cpu->stack_ptr] = cpu->pc;
for (uint32_t reg = 0; reg < REG_COUNT; reg += 4) {
uint32_t packed = cpu->regs[reg] |
((reg + 1 < REG_COUNT) ? (cpu->regs[reg + 1] << 8) : 0) |
((reg + 2 < REG_COUNT) ? (cpu->regs[reg + 2] << 16) : 0) |
((reg + 3 < REG_COUNT) ? (cpu->regs[reg + 3] << 24) : 0);
cpu->stack[++cpu->stack_ptr] = packed;
}
cpu->stack[++cpu->stack_ptr] = cpu->flags;
}
// Pop a 32-bit program counter (PC) and registers from the stack
void read_stack(CPU *cpu) {
if (cpu->stack_ptr == 0) {
return; // Stack underflow protection
}
// Restore flags
cpu->flags = cpu->stack[cpu->stack_ptr--];
// Restore registers
for (int32_t reg = REG_COUNT - 1; reg >= 0; reg -= 4) {
if (cpu->stack_ptr == 0) {
return; // Stack underflow protection
}
uint32_t packed = cpu->stack[cpu->stack_ptr--];
cpu->regs[reg] = (packed & 0xFF);
if (reg - 1 >= 0) cpu->regs[reg - 1] = ((packed >> 8) & 0xFF);
if (reg - 2 >= 0) cpu->regs[reg - 2] = ((packed >> 16) & 0xFF);
if (reg - 3 >= 0) cpu->regs[reg - 3] = ((packed >> 24) & 0xFF);
}
// Restore PC
if (cpu->stack_ptr == 0) {
return; // Stack underflow protection
}
cpu->pc = cpu->stack[cpu->stack_ptr--];
}
uint8_t read_reg_number(CPU *cpu) {
uint8_t out = read_mem(cpu, cpu->pc++);
if (out >= REG_COUNT) {