/*
 * This file is part of the TuxNES project codebase.
 *
 * Please see the README and COPYING files for more information regarding
 * this project.
 *
 * $Id: d6502.c,v 1.9 2001/04/11 21:45:47 tmmm Exp $
 *
 * Description: 6502 CPU disassembler
 */

#include <sys/types.h>
#include <stdio.h>
#include "globals.h"

void	disas(int);

char Opcodes_6502[256][4] =
{
  "BRK", "ORA", "BAD", "BAD", "BAD", "ORA", "ASL", "BAD",
  "PHP", "ORA", "ASL", "BAD", "BAD", "ORA", "ASL", "BAD",
  "BPL", "ORA", "BAD", "BAD", "BAD", "ORA", "ASL", "BAD",
  "CLC", "ORA", "BAD", "BAD", "BAD", "ORA", "ASL", "BAD",
  "JSR", "AND", "BAD", "BAD", "BIT", "AND", "ROL", "BAD",
  "PLP", "AND", "ROL", "BAD", "BIT", "AND", "ROL", "BAD",
  "BMI", "AND", "BAD", "BAD", "BAD", "AND", "ROL", "BAD",
  "SEC", "AND", "BAD", "BAD", "BAD", "AND", "ROL", "BAD",
  "RTI", "EOR", "BAD", "BAD", "BAD", "EOR", "LSR", "BAD",
  "PHA", "EOR", "LSR", "BAD", "JMP", "EOR", "LSR", "BAD",
  "BVC", "EOR", "BAD", "BAD", "BAD", "EOR", "LSR", "BAD",
  "CLI", "EOR", "BAD", "BAD", "BAD", "EOR", "LSR", "BAD",
  "RTS", "ADC", "BAD", "BAD", "BAD", "ADC", "ROR", "BAD",
  "PLA", "ADC", "ROR", "BAD", "JMP", "ADC", "ROR", "BAD",
  "BVS", "ADC", "BAD", "BAD", "BAD", "ADC", "ROR", "BAD",
  "SEI", "ADC", "BAD", "BAD", "BAD", "ADC", "ROR", "BAD",
  "BAD", "STA", "BAD", "BAD", "STY", "STA", "STX", "BAD",
  "DEY", "BAD", "TXA", "BAD", "STY", "STA", "STX", "BAD",
  "BCC", "STA", "BAD", "BAD", "STY", "STA", "STX", "BAD",
  "TYA", "STA", "TXS", "BAD", "BAD", "STA", "BAD", "BAD",
  "LDY", "LDA", "LDX", "BAD", "LDY", "LDA", "LDX", "BAD",
  "TAY", "LDA", "TAX", "BAD", "LDY", "LDA", "LDX", "BAD",
  "BCS", "LDA", "BAD", "BAD", "LDY", "LDA", "LDX", "BAD",
  "CLV", "LDA", "TSX", "BAD", "LDY", "LDA", "LDX", "BAD",
  "CPY", "CMP", "BAD", "BAD", "CPY", "CMP", "DEC", "BAD",
  "INY", "CMP", "DEX", "BAD", "CPY", "CMP", "DEC", "BAD",
  "BNE", "CMP", "BAD", "BAD", "BAD", "CMP", "DEC", "BAD",
  "CLD", "CMP", "BAD", "BAD", "BAD", "CMP", "DEC", "BAD",
  "CPX", "SBC", "BAD", "BAD", "CPX", "SBC", "INC", "BAD",
  "INX", "SBC", "NOP", "BAD", "CPX", "SBC", "INC", "BAD",
  "BEQ", "SBC", "BAD", "BAD", "BAD", "SBC", "INC", "BAD",
  "SED", "SBC", "BAD", "BAD", "BAD", "SBC", "INC", "BAD"};

/* Addressing modes */
#define ZP 1
#define ZPx 2
#define ZPy 3
#define ZPIx 4
#define ZPIy 5
#define ABS 6
#define ABSx 7
#define ABSy 8
#define IND 9
#define REL 10
#define IMM 11
unsigned char Modes_6502[256] =
{
  0, ZPIx, 0, 0, 0, ZP, ZP, 0,
  0, IMM, 0, 0, 0, ABS, ABS, 0,
  REL, ZPIy, 0, 0, 0, ZPx, ZPx, 0,
  0, ABSy, 0, 0, 0, ABSx, ABSx, 0,
  ABS, ZPIx, 0, 0, ZP, ZP, ZP, 0,
  0, IMM, 0, 0, ABS, ABS, ABS, 0,
  REL, ZPIy, 0, 0, 0, ZPx, ZPx, 0,
  0, ABSy, 0, 0, 0, ABSx, ABSx, 0,
  0, ZPIx, 0, 0, 0, ZP, ZP, 0,
  0, IMM, 0, 0, ABS, ABS, ABS, 0,
  REL, ZPIy, 0, 0, 0, ZPx, ZPx, 0,
  0, ABSy, 0, 0, 0, ABSx, ABSx, 0,
  0, ZPIx, 0, 0, 0, ZP, ZP, 0,
  0, IMM, 0, 0, IND, ABS, ABS, 0,
  REL, ZPIy, 0, 0, 0, ZPx, ZPx, 0,
  0, ABSy, 0, 0, 0, ABSx, ABSx, 0,
  0, ZPIx, 0, 0, ZP, ZP, ZP, 0,
  0, 0, 0, 0, ABS, ABS, ABS, 0,
  REL, ZPIy, 0, 0, ZPx, ZPx, ZPy, 0,
  0, ABSy, 0, 0, 0, ABSx, 0, 0,
  IMM, ZPIx, IMM, 0, ZP, ZP, ZP, 0,
  0, IMM, 0, 0, ABS, ABS, ABS, 0,
  REL, ZPIy, 0, 0, ZPx, ZPx, ZPy, 0,
  0, ABSy, 0, 0, ABSx, ABSx, ABSy, 0,
  IMM, ZPIx, 0, 0, ZP, ZP, ZP, 0,
  0, IMM, 0, 0, ABS, ABS, ABS, 0,
  REL, ZPIy, 0, 0, 0, ZPx, ZPx, 0,
  0, ABSy, 0, 0, 0, ABSx, ABSx, 0,
  IMM, ZPIx, 0, 0, ZP, ZP, ZP, 0,
  0, IMM, 0, 0, ABS, ABS, ABS, 0,
  REL, ZPIy, 0, 0, 0, ZPx, ZPx, 0,
  0, ABSy, 0, 0, 0, ABSx, ABSx, 0};

void
disas (int loc)
{
  unsigned char *ptr;
  int x;
  ptr = MAPTABLE[loc >> 12];
  while (loc < 0x10000)
    {
      x = ptr[loc];
      printf ("%4x: %1x%1x-%s ", loc++, x >> 4, x & 15, Opcodes_6502[x]);
      switch (Modes_6502[x])
        {
        case ZP:
          printf ("%1x%1x\n", ptr[loc] >> 4, ptr[loc] & 15);
          loc++;
          break;
        case ZPx:
          printf ("%1x%1x,X\n", ptr[loc] >> 4, ptr[loc] & 15);
          loc++;
          break;
        case ZPy:
          printf ("%1x%1x,Y\n", ptr[loc] >> 4, ptr[loc] & 15);
          loc++;
          break;
        case ZPIx:
          printf ("(%1x%1x,X)\n", ptr[loc] >> 4, ptr[loc] & 15);
          loc++;
          break;
        case ZPIy:
          printf ("(%1x%1x),Y\n", ptr[loc] >> 4, ptr[loc] & 15);
          loc++;
          break;
        case ABS:
          printf ("%1x%1x%1x%1x\n", ptr[loc + 1] >> 4, ptr[loc + 1] & 15,
                  ptr[loc] >> 4, ptr[loc] & 15);
          loc += 2;
          break;
        case ABSx:
          printf ("%1x%1x%1x%1x,X\n", ptr[loc + 1] >> 4, ptr[loc + 1] & 15,
                  ptr[loc] >> 4, ptr[loc] & 15);
          loc += 2;
          break;
        case ABSy:
          printf ("%1x%1x%1x%1x,Y\n", ptr[loc + 1] >> 4, ptr[loc + 1] & 15,
                  ptr[loc] >> 4, ptr[loc] & 15);
          loc += 2;
          break;
        case IND:
          printf ("(%1x%1x%1x%1x)\n", ptr[loc + 1] >> 4, ptr[loc + 1] & 15,
                  ptr[loc] >> 4, ptr[loc] & 15);
          loc += 2;
          break;
        case REL:
          if (ptr[loc] < 128)
            printf ("%4x (+%1x%1x)\n", loc + ptr[loc] + 1, ptr[loc] >> 4,
                    ptr[loc] & 15);
          else
            printf ("%4x (-%1x%1x)\n", loc + ptr[loc] - 255, ((ptr[loc] - 1)
                                                              >> 4) ^ 15,
                    ((ptr[loc] - 1) & 15) ^ 15);
          loc++;
          break;
        case IMM:
          printf ("#%1x%1x\n", ptr[loc] >> 4, ptr[loc] & 15);
          loc++;
          break;
        default:
          printf ("\n");
        }
      if (x == 0x60 || x == 0x00 || x == 0x40 || x == 0x4c || x == 0x6c || x == 0x20)
        break;
    }
}