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cpu.c
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cpu.c
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#include"cpu.h"
#include<stdlib.h>
cpu_t* cpu_create()
{
cpu_t* cpu = malloc(sizeof(cpu_t));
cpu_reset(cpu);
return cpu;
}
void cpu_reset(cpu_t* cpu)
{
cpu->reg_a = 0x00;
cpu->reg_x = 0x00;
cpu->reg_y = 0x00;
cpu->reg_p = 0x00;
cpu->reg_sp = 0x00;
cpu->reg_pc = 0x0000;
}
void cpu_execute(cpu_t* cpu, memory_t* memory)
{
cpu->opcode = memory_read(memory, cpu->reg_pc);
//cpu->cycles = instruction_table[opcode];
switch(cpu->opcode)
{
case 0x00:
i_brk(cpu);
break;
case 0x01:
m_izx(cpu);
i_ora(cpu);
break;
case 0x05:
m_zp(cpu);
i_ora(cpu);
break;
default:
return;
}
}
void cpu_close(cpu_t* cpu)
{
free(cpu);
}
/* operations */
void o_push(cpu_t* cpu, memory_t* memory, uint8_t element)
{
/*memory->ram[cpu->reg_sp] = element;*/
cpu->reg_sp--;
}
void o_pop(cpu_t* cpu, memory_t* memory)
{
}
void o_set_flag(cpu_t* cpu, char flag, uint8_t value)
{
if(value == 1)
switch(flag)
{
case 'C':
cpu->reg_p = cpu->reg_p | 0x01;
break;
case 'Z':
cpu->reg_p = cpu->reg_p | 0x02;
break;
case 'I':
cpu->reg_p = cpu->reg_p | 0x04;
break;
case 'D':
cpu->reg_p = cpu->reg_p | 0x08;
break;
case 'V':
cpu->reg_p = cpu->reg_p | 0x40;
break;
case 'N':
cpu->reg_p = cpu->reg_p | 0x80;
break;
}
else if(value == 0)
switch(flag)
{
case 'C':
cpu->reg_p = cpu->reg_p & ~0x01;
break;
case 'Z':
cpu->reg_p = cpu->reg_p & ~0x02;
break;
case 'I':
cpu->reg_p = cpu->reg_p & ~0x04;
break;
case 'D':
cpu->reg_p = cpu->reg_p & ~0x08;
break;
case 'V':
cpu->reg_p = cpu->reg_p & ~0x40;
break;
case 'N':
cpu->reg_p = cpu->reg_p & ~0x80;
break;
}
}
/* addressing modes */
void m_abs(cpu_t* cpu)
{
}
void m_abx(cpu_t* cpu)
{
}
void m_aby(cpu_t* cpu)
{
}
void m_imp(cpu_t* cpu)
{
}
void m_imm(cpu_t* cpu)
{
}
void m_ind(cpu_t* cpu)
{
}
void m_izx(cpu_t* cpu)
{
}
void m_izy(cpu_t* cpu)
{
}
void m_rel(cpu_t* cpu)
{
}
void m_zp(cpu_t* cpu)
{
}
void m_zpx(cpu_t* cpu)
{
}
void m_zpy(cpu_t* cpu)
{
}
/* instructions */
void i_brk(cpu_t* cpu)
{
/*o_push(cpu, cpu->reg_pc);
o_push(cpu, cpu->reg_p);*/
}
void i_ora(cpu_t* cpu, memory_t* memory)
{
/*cpu->reg_a = cpu->reg_a | memory_read(cpu->pc);*/
o_set_flag(cpu, 'Z', (cpu->reg_a == 0x00));
o_set_flag(cpu, 'N', ((cpu->reg_a >> 7) == 1));
}