cod2mod.c

#include <stdio.h>
#include <stdint.h>
#include <string.h>

#define BASE 48
#define STOP_BASE 35

int main(void) {
  char line[128];
  int factor;
  int rest;
  int div;
  uint8_t c, byte;

  gets(line); printf("%s\n", line);
  gets(line);

  factor = 1;
  div = 256;

  while (1) {
    if (gets(line) == 0) break;

    for (int i=0; i<strlen(line); i++) {
      c = (uint8_t)line[i];
      if (c >= BASE + 64) break;
      byte = c - BASE;
      if (factor != 1) {
        putchar(rest + (byte % div) * factor);
        rest = byte / div; 
        div = div * 4; 
        factor = factor / 4;
      } else {
        rest = byte; 
        div = 4; 
        factor = 64;
      }
    }
  }

  byte = c - STOP_BASE;
  int ok = ((byte == 0) & (div == 256)) | ((byte == 1) && (div = 16)) | ((byte == 2) && (div == 64) && (rest == 0));
  if (!ok) {
    fprintf(stderr, "decode failed!\n");
  }
}

A quick and dirty decoder to convert "AsciiCoder"-encoded (similar to base64) uncompressedd Oberon .Cod files to .Mod files