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#define _XOPEN_SOURCE 500
#include <ctype.h>
#include <errno.h>
#include <getopt.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/wait.h>
#include <unistd.h>
#ifdef __linux__
#define NASM_FORMAT "elf64"
#endif
#ifdef __APPLE__
#define NASM_FORMAT "macho64"
#endif
#ifndef NASM_FORMAT
#error "architecture not supported"
#endif
#define LABEL_COUNT_STACK_SIZE 4096
static size_t label_stack[LABEL_COUNT_STACK_SIZE + 1] = {0};
static size_t label_stack_frame = 0;
static bool compile_to_exec = true;
static char *output_filename = NULL;
static size_t buffer_len = 256;
static size_t buffer_elem_bytes = 1;
static char *elem_bytes_asm_str = "byte";
static char *elem_bytes_asm_str_res = "resb";
#define TMP_FILEPATH_TEMPLATE "/tmp/bfc_asm_XXXXXX"
#define TMP_OBJ_FILEPATH_TEMPLATE (TMP_FILEPATH_TEMPLATE ".o")
static char tmp_filepath[] = TMP_FILEPATH_TEMPLATE;
static char tmp_obj_filepath[] = TMP_OBJ_FILEPATH_TEMPLATE;
static void
die(const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
fputs("bfc: ", stderr);
vfprintf(stderr, fmt, ap);
fputc('\n', stderr);
va_end(ap);
exit(EXIT_FAILURE);
}
static size_t
xatoul(char *s)
{
if (!isdigit(*s))
die("'%s' is not a valid number", s);
char *end;
size_t num = strtoul(s, &end, 10);
if (*end != '\0')
die("'%s' is not a valid number", s);
return num;
}
static void
run_subprocess(char *name, char *const argv[])
{
pid_t pid = fork();
if (pid == -1)
die("%s", strerror(errno));
if (pid == 0)
{
execvp(name, argv);
die("%s", strerror(errno));
}
waitpid(pid, &pid, 0);
int status = WEXITSTATUS(pid);
if (status != 0)
die("%s process failed with %d\n", name, status);
}
static void
remove_tmp_file(void)
{
if (strcmp(tmp_filepath, TMP_FILEPATH_TEMPLATE) != 0)
remove(tmp_filepath);
if (strcmp(tmp_obj_filepath, TMP_OBJ_FILEPATH_TEMPLATE) != 0)
remove(tmp_obj_filepath);
}
int
main(int argc, char *argv[])
{
int option;
while ((option = getopt(argc, argv, "So:b:e:h")) != -1)
{
switch (option)
{
case 'S':
compile_to_exec = false;
break;
case 'o':
output_filename = optarg;
break;
case 'b':
buffer_len = xatoul(optarg);
break;
case 'e':
buffer_elem_bytes = xatoul(optarg);
switch (buffer_elem_bytes)
{
case 1:
elem_bytes_asm_str = "byte";
elem_bytes_asm_str_res = "resb";
break;
case 2:
elem_bytes_asm_str = "word";
elem_bytes_asm_str_res = "resw";
break;
case 4:
elem_bytes_asm_str = "dword";
elem_bytes_asm_str_res = "resd";
break;
case 8:
elem_bytes_asm_str = "qword";
elem_bytes_asm_str_res = "resq";
break;
default:
die("%lu: is not a valid number of bytes for buffer element", buffer_elem_bytes);
}
break;
case 'h':
puts("Usage: bfc [-h] [-S] [-o file] [-b buffer_len] [-e "
"buffer_elem_bytes] [INPUT_FILE]");
puts("");
puts("INPUT_FILE Brainfuck source (read stdin if not present)");
puts("");
puts("-h Print this message");
puts("-S Output assembly instead of compiled executable");
puts("-o Output filename ('-' for stdout)");
puts("-b Length of the buffer available the program");
puts("-e Number of bytes in each element of the program's "
"buffer");
puts(" (can only be: 1, 2, 4 or 8)");
exit(EXIT_SUCCESS);
}
}
if (optind > argc + 1)
die("Unexpected argument: %s\n", argv[optind + 1]);
if (output_filename == NULL)
output_filename = compile_to_exec ? "a.out" : "a.asm";
atexit(remove_tmp_file);
FILE *input_file = NULL;
if (optind == argc)
input_file = stdin;
else
{
input_file = fopen(argv[optind], "r");
if (input_file == NULL)
die("%s: %s\n", strerror(errno), argv[optind]);
}
FILE *output_file = NULL;
if (strcmp(output_filename, "-") == 0)
output_file = stdout;
else
{
if (compile_to_exec)
output_file = fdopen(mkstemp(tmp_filepath), "w");
else
output_file = fopen(output_filename, "w");
if (output_file == NULL)
die("%s: %s\n", strerror(errno), argv[optind]);
}
fprintf(output_file,
"global _start\n\n"
"section .bss\n"
"\tbuffer: %s %zu\n\n"
"section .text\n"
"_start:\n"
"\tmov rbx, buffer\n",
elem_bytes_asm_str_res,
buffer_len);
size_t label_frame_id;
char c;
while ((c = fgetc(input_file)) != EOF)
{
switch (c)
{
case '>':
fprintf(output_file, " add rbx, %zu ; >\n", buffer_elem_bytes);
break;
case '<':
fprintf(output_file, " sub rbx, %zu ; <\n", buffer_elem_bytes);
break;
case '+':
fprintf(output_file, " inc %s [rbx] ; +\n", elem_bytes_asm_str);
break;
case '-':
fprintf(output_file, " dec %s [rbx] ; -\n", elem_bytes_asm_str);
break;
case '.':
fprintf(output_file, " mov rdi, 1 ; .\n");
fprintf(output_file, " mov rsi, rbx ; .\n");
fprintf(output_file, " mov rdx, 1 ; .\n");
fprintf(output_file, " mov rax, 1 ; .\n");
fprintf(output_file, " syscall ; .\n");
break;
case ',':
fprintf(output_file, " mov rdi, 0 ; ,\n");
fprintf(output_file, " mov rsi, rbx ; ,\n");
fprintf(output_file, " mov rdx, 1 ; ,\n");
fprintf(output_file, " mov rax, 0 ; ,\n");
fprintf(output_file, " syscall ; ,\n");
break;
case '[':
label_frame_id = label_stack[label_stack_frame];
fprintf(output_file,
"label_open_%03zu_%03zu: ; [\n",
label_stack_frame,
label_frame_id);
fprintf(output_file, " cmp %s [rbx], 0 ; [\n", elem_bytes_asm_str);
fprintf(output_file,
" je label_close_%03zu_%03zu ; [\n",
label_stack_frame,
label_frame_id);
label_stack_frame++;
break;
case ']':
label_stack_frame--;
label_frame_id = label_stack[label_stack_frame];
fprintf(output_file,
"label_close_%03zu_%03zu: ; ]\n",
label_stack_frame,
label_frame_id);
fprintf(output_file, " cmp %s [rbx], 0 ; ]\n", elem_bytes_asm_str);
fprintf(output_file,
" jne label_open_%03zu_%03zu ; ]\n",
label_stack_frame,
label_frame_id);
label_stack[label_stack_frame]++;
break;
case ';':
while (c != EOF && c != '\n')
c = fgetc(input_file);
break;
default:
break;
}
}
if (input_file != stdin)
fclose(input_file);
fprintf(output_file, "\n");
fprintf(output_file, " mov rdi, 0 ; exit\n");
fprintf(output_file, " mov rax, 60 ; exit\n");
fprintf(output_file, " syscall ; exit\n");
if (output_file != stdout)
fclose(output_file);
if (compile_to_exec)
{
strcpy(tmp_obj_filepath, tmp_filepath);
strcat(tmp_obj_filepath, ".o");
char *const nasm_argv[] = {
"nasm", "-f", NASM_FORMAT, "-o", tmp_obj_filepath, tmp_filepath, NULL};
run_subprocess("nasm", nasm_argv);
char *const ld_argv[] = {"ld", "-o", output_filename, tmp_obj_filepath, NULL};
run_subprocess("ld", ld_argv);
}
return 0;
}
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