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#include <stdint.h>
struct cpu_flags {
uint8_t carry : 1;
uint8_t zero : 1;
uint8_t interrupt_disable : 1;
uint8_t decimal_mode : 1;
uint8_t brk : 1;
uint8_t unused : 1;
uint8_t overflow : 1;
uint8_t negative : 1;
};
struct registers {
uint8_t acc, x, y, sp;
struct cpu_flags status;
uint16_t pc;
};
struct registers regs;
enum addressing_mode {
AM_ACCUMULATOR,
AM_IMMEDIATE,
AM_ZERO_PAGE,
AM_ZERO_PAGE_X,
AM_ZERO_PAGE_Y,
AM_RELATIVE,
AM_ABSOLUTE,
AM_ABSOLUTE_X,
AM_ABSOLUTE_Y,
AM_INDIRECT,
AM_INDIRECT_X,
AM_INDIRECT_Y,
AM_INDEXED_INDIRECT,
AM_INDIRECT_INDEXED,
};
uint8_t addrbus[0x10000];
/* example program taken from https://bugzmanov.github.io/nes_ebook/chapter_3_1.html */
uint8_t program[] = { 0xa9, 0xc0, 0xaa, 0xe8, 0x00 };
void interpret(void)
{
uint8_t opcode;
regs.pc = 0;
for (;;) {
opcode = program[regs.pc++];
switch (opcode) {
default:
break;
}
}
}
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