/* This program compresses a file without loosing information.

/* This program compresses a file without loosing information.
* The "usq" program is required to unsqueeze the file
* before it can be used.
*
* Typical compression rates are between 30 and 50 percent for text files.
*
* Squeezing a really big file takes a few minutes.
*
* Useage:
* sq [file1] [file2] ... [filen]
*
* where file1 through filen are the names of the files to be squeezed.
* The file type (under CP/M or MS-DOS) is changed to ".?Q?"; under UN*X,
* ".SQ" is appended to the file name. The original file name is stored
* in the squeezed file.
*
* If no file name is given on the command line you will be
* prompted for commands (one at a time). An empty command
* terminates the program.
*
* The transformations compress strings of identical bytes and
* then encode each resulting byte value and EOF as bit strings
* having lengths in inverse proportion to their frequency of
* occurrance in the intermediate input stream. The latter uses
* the Huffman algorithm. Decoding information is included in
* the squeezed file, so squeezing short files or files with
* uniformly distributed byte values will actually increase size.
*/

/* CHANGE HISTORY:
* 1.3 Close files properly in case of error exit.
* 1.4 Break up long introductory lines.
* 1.4 Send introduction only to console.
* 1.4 Send errors only to console.
* 1.5 Fix BUG that caused a rare few squeezed files
* to be incorrect and fail the USQ crc check.
* The problem was that some 17 bit codes were
* generated but are not supported by other code.
* THIS IS A MAJOR CHANGE affecting TR2.C and SQ.H and
* requires recompilation of all files which are part
* of SQ. Two basic changes were made: tree depth is now
* used as a tie breaker when weights are equal. This
* makes the tree shallower. Although that may always be
* sufficient, an error trap was added to cause rescaling
* of the counts if any code > 16 bits long is generated.
* 1.5 Add debugging displays option '-'.
* 1.6 Fixed to work correctly under MP/M II. Also shortened
* signon message.
* 2.0 New version for use with CI-C86 compiler (CP/M-86 and MS-DOS)
* 2.1 Converted for use in MLINK
* 2.2 Converted for use with optimizing CI-C86 compiler (MS-DOS)
* 3.0 Generalized for UN*X use, changed output file naming convention
* 3.2 Change conversion of type from .SQ to .?Q? on non-UNIX machines
*/

/* ejecteject */

/*
* The following define MUST be set to the maximum length of a file name
* on the system "sq" is being compiled for. If not, "sq" will not be
* able to check for whether the output file name it creates is valid
* or not.
*/

#define FNM_LEN 12
/* #define UNIX /* comment out for CP/M, MS-DOS versions */
#define SQMAIN

#define VERSION "3.2 03/12/85"

#include <stdio.h>
#include "sqcom.h"
#include "sq.h"
#define FALSE 0

main(argc, argv)
int argc;
char *argv[];
{
int i,c;
char inparg[128]; /* parameter from input */

debug = FALSE;
printf("File squeezer version %s (original author: R. Greenlaw)\n\n", VERSION);

/* Process the parameters in order */
for(i = 1; i < argc; ++i)
obey(argv[i]);

if(argc < 2) {
printf("Enter file names, one line at a time, or type <RETURN> to quit.");
do {
printf("\n*");
for(i = 0; i < 16; ++i) {
if((c = getchar()) == EOF)
c = '\n'; /* fake empty (exit) command */
if((inparg[i] = c) == '\n') {
inparg[i] = '\0';
break;
}
}
if(inparg[0] != '\0')
obey(inparg);
} while(inparg[0] != '\0');
}
}

/* ejecteject */

obey(p)
char *p;
{
char *q;
char outfile[128]; /* output file spec. */

if(*p == '-') {
/* toggle debug option */
debug = !debug;
return;
}

/* Check for ambiguous (wild-card) name */
for(q = p; *q != '\0'; ++q)
if(*q == '*' || *q == '?') {
printf("\nAmbiguous name %s ignored", p);
return;
}
/* First build output file name */
strcpy(outfile, p); /* copy input name to output */

/* Find and change output file suffix */

if (strlen(outfile) + 3 > FNM_LEN) { /* check for long file name */
q = outfile + FNM_LEN - 3;
*q = '\0'; /* make room for suffix */
}
else {
q = outfile + strlen(outfile);
#ifndef UNIX
for(; --q >= outfile;)
if (*q == '.') {
if (strlen(q) == 1) /* if . */
strcat(outfile,"SQ");
else if (strlen(q) == 2) /* if .X */
strcat(outfile,"Q");
else /* must be .XX or .XXX */
*(q+2) = 'Q';
break;
}
if (q < outfile)
strcat(outfile, ".SQ");
#else
--q;
#endif
}

#ifdef UNIX
strcat(outfile, ".SQ");
#endif

squeeze(p, outfile);
}

/* ejecteject */

squeeze(infile, outfile)
char *infile, *outfile;
{
int i, c,c2;
FILE *inbuff, *outbuff; /* file buffers */

printf("%s -> %s: ", infile, outfile);

if(!(inbuff=fopen(infile, "rb"))) {
printf("Can't open %s for input pass 1\n", infile);
return;
}
if(!(outbuff=fopen(outfile, "wb"))) {
printf("Can't create %s\n", outfile);
fclose(inbuff);
return;
}

/* First pass - get properties of file */
crc = 0; /* initialize checksum */
printf("analyzing, ");
init_ncr();
init_huff(inbuff);
fclose(inbuff);

/* Write output file header with decoding info */
wrt_head(outbuff, infile);

/* Second pass - encode the file */
printf("squeezing,");
if(!(inbuff=fopen(infile, "rb"))) {
printf("Can't open %s for input pass 2\n", infile);
goto closeout;
}
init_ncr(); /* For second pass */

/* Translate the input file into the output file */
while((c = gethuff(inbuff)) != EOF)
putce(c, outbuff);
oflush(outbuff);
printf(" done.\n");
closeall:
fclose(inbuff);
closeout:
fclose(outbuff);
}