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/* ARC - Archive utility - ARCPACK
Version 3.49, created on 04/21/87 at 11:26:51
(C) COPYRIGHT 1985-87 by System Enhancement Associates.
You may copy and distribute this program freely,
under the terms of the General Public License.
By: Thom Henderson
Description:
This file contains the routines used to compress a file
when placing it in an archive.
Language:
Computer Innovations Optimizing C86
*/
#include <stdio.h>
#include "arc.h"
#if _MTS
#include <ctype.h>
#endif
#include "proto.h"
VOID setcode(), init_cm(), codebuf();
VOID arcdie(), init_sq(), flsh_cm();
int crcbuf();
u_int ncr_buf();
int lastc;
/* stuff for non-repeat packing */
#define DLE 0x90 /* repeat sequence marker */
u_char state; /* current packing state */
/* non-repeat packing states */
#define NOHIST 0 /* don't consider previous input */
#define SENTCHAR 1 /* lastchar set, no lookahead yet */
extern u_char *pinbuf;
extern u_char *pakbuf; /* worst case, 2*inbuf */
/* packing results */
long stdlen; /* length for standard packing */
short crcval; /* CRC check value */
VOID
pack(f, t, hdr) /* pack file into an archive */
FILE *f, *t; /* source, destination */
struct heads *hdr; /* pointer to header data */
{
long ncrlen; /* length after packing */
long huflen; /* length after squeezing */
long lzwlen; /* length after crunching */
long pred_sq(), head_sq(), huf_buf(); /* stuff for squeezing */
long pred_cm(); /* dynamic crunching cleanup */
long tloc, ftell(); /* start of output */
u_int inbytes = 0, pakbytes = 0;
/* first pass - see which method is best */
tloc = ftell(t); /* note start of output */
if (!nocomp) { /* if storage kludge not active */
if (note) {
printf(" analyzing, ");
fflush(stdout);
}
state = NOHIST; /* initialize ncr packing */
stdlen = ncrlen = 0; /* reset size counters */
huflen = lzwlen = 0;
crcval = 0; /* initialize CRC check value */
setcode(); /* initialize encryption */
init_sq(); /* initialize for squeeze scan */
inbytes = getbuf(f);
if (inbytes) {
init_cm(pinbuf);
for (;; inbytes = getbuf(f)) {
pakbytes = ncr_buf(inbytes);
ncrlen += pakbytes;
hufb_tab(pakbuf, pakbytes);
if (dosquash)
lzw_buf(pinbuf, inbytes, t);
else
lzw_buf(pakbuf, pakbytes, t);
if (inbytes < MYBUF)
break;
}
lzwlen = pred_cm(t);
huflen = pred_sq();
}
} else { /* else kludge the method */
stdlen = 0; /* make standard look best */
ncrlen = huflen = lzwlen = 1;
}
/* standard set-ups common to all methods */
hdr->crc = crcval; /* note CRC check value */
hdr->length = stdlen; /* set actual file length */
if (stdlen > MYBUF) {
fseek(f, 0L, 0);/* rewind input */
state = NOHIST; /* reinitialize ncr packing */
setcode(); /* reinitialize encryption */
} else
inbytes = stdlen;
/* choose and use the shortest method */
if (kludge && note)
printf("\n\tS:%ld P:%ld S:%ld C:%ld,\t ",
stdlen, ncrlen, huflen, lzwlen);
if (stdlen <= ncrlen && stdlen <= huflen && stdlen <= lzwlen) {
if (note) {
printf("storing, "); /* store without compression */
fflush(stdout);
}
hdrver = 2; /* note packing method */
fseek(t, tloc, 0); /* reset output for new method */
if (nocomp || (stdlen > MYBUF)) {
stdlen = crcval = 0;
while ((inbytes = getbuf(f)) != 0)
putb_pak(pinbuf, inbytes, t); /* store it straight */
} else
putb_pak(pinbuf, inbytes, t);
hdr->crc = crcval;
hdr->length = hdr->size = stdlen;
} else if (ncrlen < lzwlen && ncrlen < huflen) {
if (note) {
printf("packing, "); /* pack with repeat */
fflush(stdout); /* suppression */
}
hdrver = 3; /* note packing method */
hdr->size = ncrlen; /* set data length */
fseek(t, tloc, 0); /* reset output for new method */
if (stdlen > MYBUF) {
do {
inbytes = getbuf(f);
pakbytes = ncr_buf(inbytes);
putb_pak(pakbuf, pakbytes, t);
} while (inbytes != 0);
} else
putb_pak(pakbuf, pakbytes, t);
} else if (huflen < lzwlen) {
if (note) {
printf("squeezing, ");
fflush(stdout);
}
hdrver = 4; /* note packing method */
fseek(t, tloc, 0); /* reset output for new method */
huflen = head_sq();
if (stdlen > MYBUF) {
do {
inbytes = getbuf(f);
pakbytes = ncr_buf(inbytes);
huflen += huf_buf(pakbuf, pakbytes, inbytes, t);
} while (inbytes != 0);
} else
huflen += huf_buf(pakbuf, pakbytes, 0, t);
hdr->size = huflen; /* note final size */
} else {
if (note)
printf(dosquash ? "squashed, " : "crunched, ");
flsh_cm(t);
hdrver = dosquash ? 9 : 8;
hdr->size = lzwlen; /* size should not change */
}
/* standard cleanups common to all methods */
if (note)
printf("done. (%ld%%)\n", hdr->length == 0 ?
0L : 100L - (100L * hdr->size) / hdr->length);
}
/*
* Non-repeat compression - text is passed through normally, except that a
* run of more than two is encoded as:
*
* <char> <DLE> <count>
*
* Special case: a count of zero indicates that the DLE is really a DLE, not a
* repeat marker.
*/
u_int
ncr_buf(inbytes)
u_int inbytes; /* number of bytes in inbuf */
{
u_int i;
int c;
reg u_char *inptr, *pakptr;
static int cnt;
inptr = pinbuf;
pakptr = pakbuf;
if (state == NOHIST) {
lastc = (-1);
cnt = 1;
state = SENTCHAR;
}
for (i = 0; i < inbytes; i++) {
c = *inptr++;
if (c == lastc && cnt < 255)
cnt++;
else {
if (cnt == 2) {
*pakptr++ = lastc;
} else if (cnt > 2) {
*pakptr++ = DLE;
*pakptr++ = cnt;
}
*pakptr++ = c;
lastc = c;
cnt = 1;
}
if (c == DLE) {
*pakptr++ = '\0';
lastc = (-1);
}
}
if (inbytes < MYBUF && cnt > 1) { /* trailing stuff */
if (cnt == 2)
*pakptr++ = lastc;
else {
*pakptr++ = DLE;
*pakptr++ = cnt;
}
}
return (pakptr - pakbuf);
}
u_int
getbuf(f)
FILE *f;
{
u_int i;
#if !DOS
int c;
static int cr = 0;
register u_char *ptr;
if (image) {
#endif
i = fread(pinbuf, 1, MYBUF, f);
#if !DOS
} else {
ptr = pinbuf;
for (i = 0, c = 0; (c != EOF) && (i < MYBUF); i++) {
if (cr) {
c = '\n';
cr = 0;
} else {
c = fgetc(f);
if (c == EOF)
break;
else if (c == '\n') {
c = '\r';
cr = 1;
}
}
*ptr++ = c;
}
#if _MTS
etoa(pinbuf, i);
#endif /* _MTS */
}
#endif /* !DOS */
crcval = crcbuf(crcval, i, pinbuf);
stdlen += i;
return (i);
}
VOID
putb_pak(buf, len, f)
u_char *buf;
u_int len;
FILE *f;
{
u_int i;
if (f && len) {
if (password)
codebuf(buf, len);
i = fwrite(buf, 1, len, f);
if (i != len)
arcdie("Write failed");
}
}
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