janet/disasm.c

#include "disasm.h"

/* Width of padded opcode names */
#define OP_WIDTH 20

/* Print various register and arguments to instructions */
static void dasm_print_slot(FILE * out, uint16_t index) { fprintf(out, "%d ", index); }
static void dasm_print_i16(FILE * out, int16_t number) { fprintf(out, "#%d ", number); }
static void dasm_print_i32(FILE * out, int32_t number) { fprintf(out, "#%d ", number); }
static void dasm_print_f64(FILE * out, double number) { fprintf(out, "#%f ", number); }
static void dasm_print_literal(FILE * out, uint16_t index) { fprintf(out, "(%d) ", index); }
static void dasm_print_upvalue(FILE * out, uint16_t level, uint16_t index) {
    fprintf(out, "<%d, %d> ", level, index);
}

/* Print the name of the argument but pad it */
static void dasm_print_arg(FILE * out, const char * name) { 
    uint32_t i = 0;
    char c;
    while ((c = *name++)) {
        putc(c, out);
        ++i;
    }
    for (; i < OP_WIDTH; ++i)
        fputc(' ', out);
}

/* Print instructions that take a fixed number of arguments */
static uint32_t dasm_fixed_op(FILE * out, const uint16_t * current,
        const char * name, uint32_t size) {
    uint32_t i;
    dasm_print_arg(out, name);
    for (i = 1; i <= size; ++i)
        dasm_print_slot(out, current[i]);
    return size + 1;
}

/* Print instructions that take a variable number of arguments */
static uint32_t dasm_varg_op(FILE * out, const uint16_t * current,
        const char * name, uint32_t extra) {
    uint32_t i, argCount;
    dasm_print_arg(out, name);
    for (i = 0; i < extra; ++i) {
        dasm_print_slot(out, current[i + 1]);
    }
    argCount = current[extra + 1];
    fprintf(out, ": "); /* Argument separator */
    for (i = 0; i < argCount; ++i) {
        dasm_print_slot(out, current[i + extra + 2]);
    }
    return argCount + extra + 2;
}

/* Print the disassembly for a function definition */
void gst_dasm_funcdef(FILE * out, GstFuncDef * def) {
    gst_dasm(out, def->byteCode, def->byteCodeLen);
}

/* Print the disassembly for a function */
void gst_dasm_function(FILE * out, GstFunction * f) {
    gst_dasm(out, f->def->byteCode, f->def->byteCodeLen);
}

/* Disassemble some bytecode and display it as opcode + arguments assembly */
void gst_dasm(FILE * out, uint16_t *byteCode, uint32_t len) {
    uint16_t *current = byteCode;
    uint16_t *end = byteCode + len;

    while (current < end) {
        switch (*current) {
            default:
                current += dasm_fixed_op(out, current, "unknown", 0);
                break;
            case GST_OP_ADD:
                current += dasm_fixed_op(out, current, "add", 3);
                break;
            case GST_OP_SUB:
                current += dasm_fixed_op(out, current, "sub", 3);
                break;      
            case GST_OP_MUL:
                current += dasm_fixed_op(out, current, "mul", 3);
                break;      
            case GST_OP_DIV:
                current += dasm_fixed_op(out, current, "div", 3);
                break;
            case GST_OP_NOT:
                current += dasm_fixed_op(out, current, "not", 2);
                break;
            case GST_OP_FLS:
                current += dasm_fixed_op(out, current, "loadFalse", 1);
                break;
            case GST_OP_TRU:
                current += dasm_fixed_op(out, current, "loadTrue", 1);
                break;
            case GST_OP_NIL:
                current += dasm_fixed_op(out, current, "loadNil", 1);
                break;
            case GST_OP_I16:
                dasm_print_arg(out, "loadInt16");
                dasm_print_slot(out, current[1]);
                dasm_print_i16(out, ((int16_t *)current)[2]);
                current += 3;
                break;
            case GST_OP_UPV:
                dasm_print_arg(out, "loadUpValue");
                dasm_print_slot(out, current[1]);
                dasm_print_upvalue(out, current[2], current[3]);
                current += 4;
                break;
            case GST_OP_JIF:
                dasm_print_arg(out, "jumpIf");
                dasm_print_slot(out, current[1]);
                dasm_print_i32(out, ((int32_t *)(current + 2))[0]);
                current += 4;
                break;
            case GST_OP_JMP:
                dasm_print_arg(out, "jump");
                dasm_print_i32(out, ((int32_t *)(current + 1))[0]);
                current += 3;
                break;
            case GST_OP_SUV:
                dasm_print_arg(out, "setUpValue");
                dasm_print_slot(out, current[1]);
                dasm_print_upvalue(out, current[2], current[3]);
                current += 4;
                break;
            case GST_OP_CST:
                dasm_print_arg(out, "loadLiteral");
                dasm_print_slot(out, current[1]);
                dasm_print_literal(out, current[2]);
                current += 3;
                break;
            case GST_OP_I32:
                dasm_print_arg(out, "loadInt32");
                dasm_print_slot(out, current[1]);
                dasm_print_i32(out, ((int32_t *)(current + 2))[0]);
                current += 4;
                break;
            case GST_OP_F64:
                dasm_print_arg(out, "loadFloat64");
                dasm_print_slot(out, current[1]);
                dasm_print_f64(out, ((double *)(current + 2))[0]);
                current += 6;
                break;
            case GST_OP_MOV:
                current += dasm_fixed_op(out, current, "move", 2);
                break;
            case GST_OP_CLN:
                dasm_print_arg(out, "makeClosure");
                dasm_print_slot(out, current[1]);
                dasm_print_literal(out, current[2]);
                current += 3;
                break;
            case GST_OP_EQL:
                current += dasm_fixed_op(out, current, "equals", 3);
                break;
            case GST_OP_LTN:
                current += dasm_fixed_op(out, current, "lessThan", 3);
                break;
            case GST_OP_LTE:
                current += dasm_fixed_op(out, current, "lessThanEquals", 3);
                break;
            case GST_OP_ARR:
                current += dasm_varg_op(out, current, "array", 1);
                break;
            case GST_OP_DIC:
                current += dasm_varg_op(out, current, "object", 1);
                break;
            case GST_OP_TUP:
                current += dasm_varg_op(out, current, "tuple", 1);
                break;
            case GST_OP_GET:
                current += dasm_fixed_op(out, current, "get", 3);
                break;
            case GST_OP_SET:
                current += dasm_fixed_op(out, current, "set", 3);
                break;
            case GST_OP_ERR:
                current += dasm_fixed_op(out, current, "error", 1);
                break;
            case GST_OP_TRY:
                dasm_print_arg(out, "try");
                dasm_print_slot(out, current[1]);
                dasm_print_i32(out, *(int32_t *)(current + 2));
                current += 4;
                break;
            case GST_OP_UTY:
                current += dasm_fixed_op(out, current, "untry", 0);
                break;
            case GST_OP_RET:
                current += dasm_fixed_op(out, current, "return", 1);
                break;
            case GST_OP_RTN:
                current += dasm_fixed_op(out, current, "returnNil", 0);
                break;
            case GST_OP_CAL:
                current += dasm_varg_op(out, current, "call", 2);
                break;
            case GST_OP_TCL:
                current += dasm_varg_op(out, current, "tailCall", 1);
                break;
        }
        fprintf(out, "\n");
    }
}