#include "boot.h"
#include "cpu.h"
#include "insn.h"
#include "psx.h"

#include <assert.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

static const uint8_t MAGIC[0x10] = "PS-X EXE";
static const uint8_t RESERVED[0x10] = {0};

psx_header_t parse_psx_header(byte_arr_t *prgm)
{
    psx_header_t header;

    // TODO: Convert asserts into recoverable error
    assert(sizeof header == 0x38 - 0x10);
    assert(prgm->size >= 0x800);
    assert(memcmp(MAGIC, prgm->data, sizeof MAGIC) == 0);
    memcpy(&header, &prgm->data[sizeof MAGIC], sizeof header);

    assert(header.size_file == prgm->size - 0x800);
    assert(memcmp(RESERVED, &prgm->data[0x38], sizeof RESERVED) == 0);

    return header;
}

uint32_t translate_addr(uint32_t addr)
{
    if (addr >= 0xA0000000)
    {
        addr = addr - 0xA0000000;
    }
    else if (addr >= 0x80000000)
    {
        addr = addr - 0x80000000;
    }

    return addr;
}

void boot_psx_prgm(byte_arr_t *prgm)
{
    printf("parsing program header\n");

    psx_header_t header = parse_psx_header(prgm);

    printf("=== header ===\n");
    printf("pc = %08x, gp = %08x\n", header.pc, header.gp);
    printf("sp = %08x, fp = %08x\n", header.sp, header.fp);
    printf("data = %08x (%u bytes)\n", header.addr_data, header.size_data);
    printf("bss = %08x (%u bytes)\n", header.addr_bss, header.size_bss);
    printf("dest = %08x\n", header.addr_dest);
    printf("size = %08x (%u bytes)\n", header.size_file, header.size_file);

    cpu_t *cpu = malloc(sizeof *cpu);

    uint32_t start = translate_addr(header.addr_dest);
    assert(start + header.size_file < MAIN_RAM_SIZE);
    memcpy(&cpu->main_ram[start], &prgm->data[0x800], header.size_file);

    cpu->pc = header.pc;
    cpu->regs[REG_GP] = header.gp;
    cpu->regs[REG_SP] = header.sp;
    cpu->regs[REG_FP] = header.fp;

    psx_t psx = {header, cpu};
    const int max_insns = 1;

    for (int i = 0; i < max_insns; i++)
    {
        printf("=== insn ===\n");
        printf("pc = %08x\n", psx.cpu->pc);

        const uint32_t insn = cpu_read32(cpu, psx.cpu->pc);
        insn_execute(cpu, insn);

        psx.cpu->pc += 1;
    }
}