D PRG/ATOB-22.C

/*
 * atob  version 2.2 for cpm/msdos on packet radio
 *       a program to transform binary to printable ASCII at a minimal*
 *       'cost' in conversion space - ratio is about 5/4
 *
 * atob: version 4.0
 * stream filter to change printable ascii from "btoa" back into 8 bit*
 * bytes if bad chars, or Csums do not match: exit(1) [and NO output] *
 *
 *  Paul Rutter      Joe Orost
 *  philabs!per      petsd!joe
 *
 *
 *                                                                    *
 *  86May30 - corrected 'y' as file name in duplicate target file and *
 *            added ability to have garbage in front of, on the same  *
 *            line with the 'xbtoa Begin' line |br| ka2bqe         *
 *  86May19 - modified to command line parsing, and recovery of input *
 *            file name from header line. Should be able to handle ver*
 *            sion 1.0 files w/o file name in header |br| - ka2bqe    *
 *  86May05 - modified to compile/run for packet radio under cpm-80 & *
 *            msdos by Brian B. Riley (ka2bqe) - RATS            *
 *  Hacked to work with non-UNIX machines by Brian Lloyd, 86/04/17    *
 *                                                                    *
 */

#include <stdio.h>
#define reg register
#define streq(s0, s1)  strcmp(s0, s1) == 0
#define times85(x)   ((((((x<<2)+x)<<2)+x)<<2)+x)

long int Ceor = 0;
long int Csum = 0;
long int Crot = 0;
long int word = 0;
long int bcount = 0;

FILE *      inf;
FILE *      outf;

#define DE(c) ((c) - '!')

/*
 * main - this is the ASCII-to-BINARY recovery routine. It queries for
 *        and opens files and stream decodes and verifies checksum
 */

main(argc, argv)
char **argv;
{
   reg c;
   reg long int i;
   char   infile[64];
   char   outfile[64];
   char   buf[100];
   long int n1, n2, oeor, osum, orot;

   printf("\n atob: Ascii-to-Binary recovery\n RATS v2.2\n");

   if(argc<2) {printf("Usage: atob infile \n");exit(2);}
   strcpy(infile,argv[1]);  /* get inputfile name */
   while ((inf = fopen(infile, "r")) == NULL) {
       printf("\n Error opening file - %s\n Input file:  ",infile);
       if (gets(infile)==NULL) exit();
        }

   /*search for header line*/
   while ((c=getc(inf))!=EOF) {/* look for 'x'*/
       if (c=='x') {
      if (fgets(buf, sizeof buf, inf) != NULL) {
          if (strncmp(buf, "btoa Begin",10) == 0) break;
      } else {printf("\n\7 *** EOF in header scan.\n" ); exit(0);}
       }
   }
   if (c==EOF) {printf("\n\7 *** EOF in header scan.\n");exit(0);}

   outfile[0] = '\0';   /* null outfile name string */
   sscanf(buf,"btoa Begin %s\n",outfile);
        if (strlen(outfile) ) {
       printf("\n Header found ===> File: [%s] ",outfile);
   } else {
       printf( "\n Possible OLD header - Enter output file:  ");
       if (gets(outfile)==NULL) exit();
        }
   while ((outf = fopen(outfile,"r")) != NULL) {
       fclose(outf);
       printf("\n Target file name exists! Overwrite (Y/N) ? ");
       gets(buf);
       if (toupper(buf[0]) == 'Y') {break;}
        else {
      printf (" Enter new output filename : ");
      gets(outfile);
       }
   }
   fclose(outf);
   printf(" ===> Decoding ");
        if ((outf = fopen(outfile, "w")) == NULL) {
       printf( " File OPEN ERROR - [%s] - Disk full ???\n",outfile);
       fclose(outf);
       exit();
        }

   while ((c = getc(inf)) != EOF) {
      if (c == '\n') {continue;}
       else if (c=='\r') {continue;}
       else if (c == 'x') {break;}
       else {decode(c);}
   }

   printf(" ===> *** EOF ***\n Checking trailer now");

   if(fscanf(inf,"btoa End N %ld %lx E %lx S %lx R %lx\n",
             &n1, &n2, &oeor, &osum, &orot) != 5) {
      printf(" ===> \7Failure reading the trailer line.\n" );
      exit(0);
   }
   if ((n1 != n2) || (oeor != Ceor) || (osum != Csum) || (orot != Crot)) {
      printf(" ===> \7File checksum is bad.\n");
      exit(0);
   } else {
      printf(" ===> File checksum is good.\n");
   }
   fclose( inf );
   fclose( outf );
   exit(0);
}

/*
 * byteout - outputs a single binary byte to file                       *
 */
byteout(c)
   reg c;
{
   Ceor ^= c;
   Csum += c;
   Csum += 1;
   if ((Crot & 0x80000000L)) {
      Crot <<= 1;
      Crot += 1;
   } else {
      Crot <<= 1;
   }
   Crot += c;
   putc(c, outf);
}


/*
 * decode - stream decodes 5 'digit' ASCII  back to 4 byte binary       *
 */
decode(c)
   reg c;
{

   if (c == 'z') {
      if (bcount != 0) {
         printf("z not on word boundary in decode.\n");
         exit(0);
      } else {
         byteout(0);
         byteout(0);
         byteout(0);
         byteout(0);
      }
   } else if ((c >= '!') && (c < ('!' + 85))) {
      if (bcount == 0) {
         word = DE(c);
         ++bcount;
      } else if (bcount < 4) {
         word = times85(word);
         word += DE(c);
         ++bcount;
      } else {
         word = times85(word) + DE(c);
         byteout((int)((word >> 24) & 255));
         byteout((int)((word >> 16) & 255));
         byteout((int)((word >> 8) & 255));
         byteout((int)(word & 255));
         word = 0;
         bcount = 0;
      }
   } else {
      printf("Input character out of range in decode.(%02x)\n",c);
      exit(0);
   }
}