compiler.c

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#include <stdlib.h>

#include "common.h"

#define BUF_SIZE 256

int compile(FILE *in, FILE *out, int stack_size, int array_size)
{
        int c, ret = 0;
        unsigned long label_num = 0L;
        int stack_ptr = 0;
        unsigned long *stack = malloc(stack_size * sizeof *stack);
        if (stack == NULL) {
                fprintf(stderr, "error: couldn't allocate stack (%lu bytes)\n", stack_size * sizeof *stack);
                ret = -1;
                goto cleanup;
        }
        char buf[BUF_SIZE];
        snprintf(buf, BUF_SIZE, "\t.lcomm buffer %d\n", array_size);
        fputs("\t.section .bss\n", out);
        fputs(buf, out);
        fputs("\n", out);
        fputs("\t.section .text\n", out);
        fputs("\t.globl _start\n", out);
        fputs("_start:\n", out);
        fputs("\tmovl $buffer, %edi\n", out);
        fputs("\n", out);
        while ((c = fgetc(in)) != EOF) {
                switch (c) {
                case '>':
                        fputs("\tinc %edi\n", out);
                        fputs("\n", out);
                        break;
                case '<':
                        fputs("\tdec %edi\n", out);
                        fputs("\n", out);
                        break;
                case '+':
                        fputs("\tincb (%edi)\n", out);
                        fputs("\n", out);
                        break;
                case '-':
                        fputs("\tdecb (%edi)\n", out);
                        fputs("\n", out);
                        break;
                case '.':
                        fputs("\tmovl $4, %eax\n", out);
                        fputs("\tmovl $1, %ebx\n", out);
                        fputs("\tmovl %edi, %ecx\n", out);
                        fputs("\tmovl $1, %edx\n", out);
                        fputs("\tint $0x80\n", out);
                        fputs("\n", out);
                        break;
                case ',':
                        fputs("\tmovl $3, %eax\n", out);
                        fputs("\tmovl $0, %ebx\n", out);
                        fputs("\tmovl %edi, %ecx\n", out);
                        fputs("\tmovl $1, %edx\n", out);
                        fputs("\tint $0x80\n", out);
                        fputs("\n", out);
                        break;
                case '[':
                        if (stack_ptr == stack_size) {
                                stack_size *= 2;
                                unsigned long *temp = realloc(stack, stack_size * sizeof *stack);
                                if (temp == NULL) {
                                        fprintf(stderr, "error: couldn't reallocate stack (%lu bytes)\n", stack_size * sizeof *stack);
                                        ret = -1;
                                        goto cleanup;
                                }
                                stack = temp;
                        }
                        stack[stack_ptr++] = ++label_num;
                        fputs("\tcmpb $0, (%edi)\n", out);
                        snprintf(buf, BUF_SIZE, "\tjz .LE%lu\n", label_num);
                        fputs(buf, out);
                        snprintf(buf, BUF_SIZE, ".LB%lu:\n", label_num);
                        fputs(buf, out);
                        break;
                case ']':
                        fputs("\tcmpb $0, (%edi)\n", out);
                        snprintf(buf, BUF_SIZE, "\tjnz .LB%lu\n", stack[--stack_ptr]);
                        fputs(buf, out);
                        snprintf(buf, BUF_SIZE, ".LE%lu:\n", stack[stack_ptr]);
                        fputs(buf, out);
                        break;
                default:
                        break;
                }
        }
        fputs("\n", out);
        fputs("\tmovl $1, %eax\n", out);
        fputs("\tmovl $0, %ebx\n", out);
        fputs("\tint $0x80\n", out);
        fputs("\n", out);
cleanup:
        if (stack)
                free(stack);
        return ret;
}