debug.c

#include <stdio.h>
#include "debug.h"
#include "chunk.h"
#include "object.h"

void disassembleChunk(Chunk* chunk, const char *name) {
    printf("== %s ==\n", name); 
    for (int offset = 0; offset < chunk->count;) 
        offset = disassembleInstruction(chunk, offset);
}

static int simpleInstruction(const char* name, int offset) {
    printf("%s\n", name);
    return offset + 1;
}

static int byteInstruction(const char* name, Chunk* chunk, int offset) {
    uint8_t slot = chunk->code[offset + 1];
    printf("%-16s %4d\n", name, slot);
    return offset + 2;
}

static int jumpInstruction(const char* name, int sign, Chunk* chunk, int offset) {
    uint16_t jump = (uint16_t)(chunk->code[offset + 1] << 8);
    jump |= chunk->code[offset + 2];
    printf("%-16s %4d -> %d\n", name, offset, offset + 3 + sign * jump);
    return offset + 3;
}

static int constantInstruction(const char* name, Chunk* chunk, int offset) {
    uint8_t constant = chunk->code[offset + 1]; // accessing index of the constant
    printf("%-16s %d '", name, constant);
    printValue(chunk->constants.values[constant]);
    printf("'\n");

    return offset + 2;
}

/*
    disassembleInstruction returns a number to tell the caller the 
    offset of the beginning of the next instruction
*/
int disassembleInstruction(Chunk* chunk, int offset) {
    printf("%04d ", offset); // prints the byte offset of each instruction
    
    if (offset > 0 && chunk->lines[offset] == chunk->lines[offset - 1])
        printf("    | "); // we show a '|' for any instruction that comes from the same source line as the preceding one
    else printf("%4d ", chunk->lines[offset]);

    uint8_t instruction = chunk->code[offset]; // reads single byte from bytecode
    switch (instruction) {
        case OP_CONSTANT:
            return constantInstruction("OP_CONSTANT", chunk, offset);
        case OP_NIL:
            return simpleInstruction("OP_NIL", offset);
        case OP_TRUE:
            return simpleInstruction("OP_TRUE", offset);
        case OP_FALSE:
            return simpleInstruction("OP_FALSE", offset);
        case OP_POP:
            return simpleInstruction("OP_POP", offset);
        case OP_GET_LOCAL:
            return byteInstruction("OP_GET_LOCAL", chunk, offset);
        case OP_SET_LOCAL:
            return byteInstruction("OP_SET_LOCAL", chunk, offset);
        case OP_GET_GLOBAL:
            return constantInstruction("OP_GET_GLOBAL", chunk, offset);
        case OP_DEFINE_GLOBAL:
            return constantInstruction("OP_DEFINE_GLOBAL", chunk, offset);
        case OP_SET_GLOBAL:
            return  constantInstruction("OP_SET_GLOBAL", chunk, offset);
        case OP_GET_UPVALUE:
            return byteInstruction("OP_GET_UPVALUE", chunk, offset);
        case OP_SET_UPVALUE:
            return byteInstruction("OP_SET_UPVALUE", chunk, offset);
        case OP_EQUAL:
            return simpleInstruction("OP_EQUAL", offset);
        case OP_GREATER:
            return simpleInstruction("OP_GREATER", offset);
        case OP_LESS:
            return simpleInstruction("OP_LESS", offset);
        case OP_ADD:
            return simpleInstruction("OP_ADD", offset);
        case OP_SUBTRACT:
            return simpleInstruction("OP_SUBTRACT", offset);
        case OP_MULTIPLY:
            return simpleInstruction("OP_MULTIPLY", offset);
        case OP_DIVIDE:
            return simpleInstruction("OP_DIVIDE", offset);
        case OP_NOT:
            return simpleInstruction("OP_NOT", offset);
        case OP_NEGATE:
            return simpleInstruction("OP_NEGATE", offset);
        case OP_PRINT:
            return simpleInstruction("OP_PRINT", offset);
        case OP_JUMP:
            return jumpInstruction("OP_JUMP", 1, chunk, offset);
        case OP_JUMP_IF_FALSE:
            return jumpInstruction("OP_JUMP_IF_FALSE", 1, chunk, offset);
        case OP_LOOP:
            return jumpInstruction("OP_LOOP", -1, chunk, offset);
        case OP_CALL:
            return byteInstruction("OP_CALL", chunk, offset);
        case OP_CLOSURE: {
            offset++;
            uint8_t constant = chunk->code[offset++];
            printf("%-16s %4d ", "OP_CLOSURE", constant);
            printValue(chunk->constants.values[constant]);
            printf("\n");

            ObjFunction* function = AS_FUNCTION(
                chunk->constants.values[constant]
            );

            for (int j = 0; j < function->upvalueCount; ++j) {
                int isLocal = chunk->code[offset++];
                int index = chunk->code[offset++];
                printf("%04d        |                 %s %d\n",
                        offset - 2, isLocal ? "local" : "upvalue",
                        index);
            }

            return offset;
        }
        case OP_CLOSE_UPVALUE:
            return simpleInstruction("OP_CLOSE_UPVALUE", offset);
        case OP_RETURN:
            return simpleInstruction("OP_RETURN", offset);
        default:
            printf("Unknown opcode %d\n", instruction);
            return offset + 1;
    }
}

/*
    Example:

    == test chunk ==
    0000 OP_RETURN
*/