c0vm_main.c

/**************************************************************************/
/*              COPYRIGHT Carnegie Mellon University 2024                 */
/* Do not post this file or any derivative on a public site or repository */
/**************************************************************************/
/* C0VM, main file
 * 15-122, Fall 2010
 * William Lovas, Tom Cortina, Frank Pfenning
 *
 * Performs some OS compatibility checks before
 * running the VM.
 */
#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <alloca.h>
#include "lib/c0vm.h"

/* for the args library */
int c0_argc;
char **c0_argv;

/* fail-fast file function wrappers */
FILE *xfopen(const char *filename, const char *mode, char *error) {
  FILE *f = fopen(filename, mode);
  if (f == NULL) {
    perror(error);
    exit(EXIT_FAILURE);
  }
  return f;
}

void xfwrite(const void *ptr, size_t size, size_t nitems, FILE *stream,
         char *error) {
  if (fwrite(ptr, size, nitems, stream) < nitems) {
    perror(error);
    exit(EXIT_FAILURE);
  }
}

void xfclose(FILE *stream, char *error) {
  if (fclose(stream) != 0) {
    perror(error);
    exit(EXIT_FAILURE);
  }
}

int main(int argc, char **argv) {
  if (argc < 2) {
    fprintf(stderr, "usage: %s <bc0_file> [args...]\n", argv[0]);
    exit(1);
  }

  /* test for two's complement */
  if (~(-1) != 0) {
    fprintf(stderr, "Error: not a two's complement machine\n");
    exit(1);
  }

  /* test representation sizes */
  if (sizeof(int) != 4) {
    fprintf(stderr, "Error: sizeof(int) == %zd != 4\n", sizeof(int));
    exit(1);
  }

  if (CHAR_BIT != 8) {
    fprintf(stderr, "Error: CHAR_BITS == %d != 8\n", CHAR_BIT);
    exit(1);
  }

  /* test of sign-extending shift */
  if ((int)(-1) >> 31 != -1) {
    fprintf(stderr, "Error: right shift does not sign-extend\n");
    exit(1);
  }

  /* for the args library -- skip the binary name */
  c0_argc = argc - 1;
  c0_argv = argv + 1;

  char *filename = getenv("C0_RESULT_FILE");

  struct bc0_file *bc0 = read_program(argv[1]);

  // Move string pool to stack
  char *stack_allocate_string_pool = alloca(bc0->string_count);
  for (size_t i = 0; i < bc0->string_count; i++) {
    stack_allocate_string_pool[i] = bc0->string_pool[i];
  }
  free(bc0->string_pool);
    bc0->string_pool = stack_allocate_string_pool;

  if (filename == NULL) {
    int result = execute(bc0);
    printf("%d\n", result);
  } else {
    FILE *f = xfopen(filename, "w", "Couldn't open $C0_RESULT_FILE");
    xfwrite("\0", 1, 1, f, "Couldn't write to $C0_RESULT_FILE");
    int result = execute(bc0);
    printf("Result = %d\n", result);
    xfwrite(&result, sizeof(int), 1, f, "Couldn't write to $C0_RESULT_FILE");
    xfclose(f, "Couldn't close $C0_RESULT_FILE");
  }

  free_program(bc0);
  return 0;
}