mirror of
https://github.com/rkujawa/rk65c02.git
synced 2024-06-23 08:29:36 +00:00
127 lines
2.2 KiB
C
127 lines
2.2 KiB
C
#include <stdio.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <stdbool.h>
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#include <assert.h>
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#include <string.h>
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#include "bus.h"
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#include "65c02isa.h"
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#include "instruction.h"
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instruction_t
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instruction_fetch(bus_t *b, uint16_t addr)
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{
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instruction_t i;
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uint8_t op;
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op = bus_read_1(b, addr);
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i.def = instrdef_get(op);
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assert(i.def.opcode != OP_UNIMPL);
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/* handle operands */
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switch (i.def.mode) {
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case IMMEDIATE:
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case ZP:
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case ZPX:
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case ZPY:
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case IZP:
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case IZPX:
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case IZPY:
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case RELATIVE:
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i.op1 = bus_read_1(b, addr+1);
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break;
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case ABSOLUTE:
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case ABSOLUTEX:
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case ABSOLUTEY:
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case IABSOLUTE:
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case IABSOLUTEX:
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i.op1 = bus_read_1(b, addr+1);
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i.op2 = bus_read_1(b, addr+2);
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break;
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case IMPLIED:
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default:
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break;
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}
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return i;
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}
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void
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instruction_print(instruction_t *i)
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{
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switch (i->def.mode) {
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case IMPLIED:
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printf("%s", i->def.mnemonic);
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break;
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case ACCUMULATOR:
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printf("%s A", i->def.mnemonic);
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break;
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case IMMEDIATE:
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printf("%s #%X", i->def.mnemonic, i->op1);
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break;
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case ZP:
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printf("%s %X", i->def.mnemonic, i->op1);
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break;
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case ZPX:
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printf("%s %X,X", i->def.mnemonic, i->op1);
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break;
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case ZPY:
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printf("%s %X,Y", i->def.mnemonic, i->op1);
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break;
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case IZP:
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printf("%s (%X)", i->def.mnemonic, i->op1);
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break;
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case IZPX:
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printf("%s (%X,X)", i->def.mnemonic, i->op1);
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break;
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case IZPY:
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printf("%s (%X),Y", i->def.mnemonic, i->op1);
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break;
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case ABSOLUTE:
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printf("%s %02X%02X", i->def.mnemonic, i->op2, i->op1);
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break;
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case ABSOLUTEX:
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printf("%s %02X%02X,X", i->def.mnemonic, i->op2, i->op1);
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break;
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case ABSOLUTEY:
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printf("%s %02X%02X,Y", i->def.mnemonic, i->op2, i->op1);
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break;
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case IABSOLUTE:
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printf("%s (%02X%02X)", i->def.mnemonic, i->op2, i->op1);
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break;
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case IABSOLUTEX:
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printf("%s (%02X%02X,X)", i->def.mnemonic, i->op2, i->op1);
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break;
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case RELATIVE:
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printf("%s %02X%02X", i->def.mnemonic, i->op2, i->op1);
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break;
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}
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}
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void
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disassemble(bus_t *b, uint16_t addr)
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{
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instruction_t i;
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i = instruction_fetch(b, addr);
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printf("%X:\t", addr);
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instruction_print(&i);
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printf("\t\t// %X", i.def.opcode);
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printf("\n");
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}
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instrdef_t
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instrdef_get(uint8_t opcode)
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{
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instrdef_t id;
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id = instrs[opcode];
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return id;
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}
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