Replace fix-rom script with utils binary

src/utils/fix-rom.c

@@ -0,0 +1,36 @@
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+struct stat sbuf;
+
+int main(int argc, char** argv) {
+  FILE* fd = fopen(argv[1], "r+");
+  fstat(fileno(fd), &sbuf);
+  if (sbuf.st_size & 0x1F) {
+    fprintf(stderr, "Filesize is not a multiple of 512 bytes\n");
+    exit(1);
+  }
+
+  // Fill out filesize flag
+  fseek(fd, 2, SEEK_SET);
+  fputc(sbuf.st_size >> 9, fd);
+
+  // Calculate checksum
+  fseek(fd, 0, SEEK_SET);
+  off_t i;
+  uint8_t s;
+  for (i=0; i<sbuf.st_size; i++) {
+    s+=fgetc(fd);
+  }
+
+  // Edit last byte so that checksum is 0
+  fseek(fd, -1, SEEK_END);
+  s=fgetc(fd)-s;
+  fseek(fd, -1, SEEK_END);
+  fputc(s, fd);
+
+  fclose(fd);
+}