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nushk.c
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nushk.c
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/*
* nushk.c - P8 ShrinkIt compress/uncompress routines
*
* NuLib v3.2 March 1992 Freeware (distribute, don't sell)
* By Andy McFadden (fadden@uts.amdahl.com)
*/
#ifdef APW
segment "Compress"
#endif
#include "nudefs.h"
#include "stdio.h"
#include <fcntl.h>
#ifdef UNIX
# include <sys/types.h>
#endif
#ifdef MSDOS /* For file IO */
# include <io.h>
# include <sys/types.h>
# include <sys/stat.h>
# include <errno.h>
#endif
#include "nuread.h" /* need CalcCRC() */
#include "nupak.h"
#include "nuetc.h"
#ifdef UNIX
# ifdef SYSV
# define BCOPY(src, dst, count) memcpy(dst, src, count)
# else
# define BCOPY(src, dst, count) bcopy(src, dst, count);
# endif
#else
# ifdef APW
# define BCOPY(src, dst, count) memcpy(dst, src, count)
# endif
# ifdef MSDOS /* you may need to change this to memcpy() */
# define BCOPY(src, dst, count) bcopy(src, dst, count);
/*# define BCOPY(src, dst, count) memcpy(dst, src, count)*/
# endif
/* +PORT+ */
#endif
#define BLKSIZ 4096
/*#define DEBUG /* do verbose debugging output */
/*#define DEBUG1 /* debugging output in main routine */
static onebyt *ibuf; /* large buffer (usually set to packBuffer) */
onebyt lbuf[BLKSIZ+7]; /* temporary buffer for storing data after LZW */
onebyt rbuf[BLKSIZ+7]; /* temporary buffer for storing data after RLE */
/*
* P8 ShrinkIt compression routines
* Copyright 1989 Kent Dickey
*
* C translation by Kent Dickey / Andy McFadden
*/
#define ESCAPE_CHAR 0xdb
#define HSIZE 5119 /* Must be prime */
typedef struct ht {
int entry;
int prefix;
onebyt chr;
};
struct ht *htab = NULL; /* allocated first time through */
int s_at_bit;
int s_at_byte;
int mask[] = { 0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f,
0xff, 0x1ff, 0x3ff, 0x7ff, 0xfff };
int bit_tab[] = { 0,9,10, 10, 11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 12, 12 };
/* hash function from UNIX compress */
int hashf[256] = {
0x0000, 0x0204, 0x0408, 0x060c, 0x0810, 0x0a14, 0x0c18, 0x0e1c,
0x0020, 0x0224, 0x0428, 0x062c, 0x0830, 0x0a34, 0x0c38, 0x0e3c,
0x0040, 0x0244, 0x0448, 0x064c, 0x0850, 0x0a54, 0x0c58, 0x0e5c,
0x0060, 0x0264, 0x0468, 0x066c, 0x0870, 0x0a74, 0x0c78, 0x0e7c,
0x0080, 0x0284, 0x0488, 0x068c, 0x0890, 0x0a94, 0x0c98, 0x0e9c,
0x00a0, 0x02a4, 0x04a8, 0x06ac, 0x08b0, 0x0ab4, 0x0cb8, 0x0ebc,
0x00c0, 0x02c4, 0x04c8, 0x06cc, 0x08d0, 0x0ad4, 0x0cd8, 0x0edc,
0x00e0, 0x02e4, 0x04e8, 0x06ec, 0x08f0, 0x0af4, 0x0cf8, 0x0efc,
0x0100, 0x0304, 0x0508, 0x070c, 0x0910, 0x0b14, 0x0d18, 0x0f1c,
0x0120, 0x0324, 0x0528, 0x072c, 0x0930, 0x0b34, 0x0d38, 0x0f3c,
0x0140, 0x0344, 0x0548, 0x074c, 0x0950, 0x0b54, 0x0d58, 0x0f5c,
0x0160, 0x0364, 0x0568, 0x076c, 0x0970, 0x0b74, 0x0d78, 0x0f7c,
0x0180, 0x0384, 0x0588, 0x078c, 0x0990, 0x0b94, 0x0d98, 0x0f9c,
0x01a0, 0x03a4, 0x05a8, 0x07ac, 0x09b0, 0x0bb4, 0x0db8, 0x0fbc,
0x01c0, 0x03c4, 0x05c8, 0x07cc, 0x09d0, 0x0bd4, 0x0dd8, 0x0fdc,
0x01e0, 0x03e4, 0x05e8, 0x07ec, 0x09f0, 0x0bf4, 0x0df8, 0x0ffc,
0x0200, 0x0004, 0x0608, 0x040c, 0x0a10, 0x0814, 0x0e18, 0x0c1c,
0x0220, 0x0024, 0x0628, 0x042c, 0x0a30, 0x0834, 0x0e38, 0x0c3c,
0x0240, 0x0044, 0x0648, 0x044c, 0x0a50, 0x0854, 0x0e58, 0x0c5c,
0x0260, 0x0064, 0x0668, 0x046c, 0x0a70, 0x0874, 0x0e78, 0x0c7c,
0x0280, 0x0084, 0x0688, 0x048c, 0x0a90, 0x0894, 0x0e98, 0x0c9c,
0x02a0, 0x00a4, 0x06a8, 0x04ac, 0x0ab0, 0x08b4, 0x0eb8, 0x0cbc,
0x02c0, 0x00c4, 0x06c8, 0x04cc, 0x0ad0, 0x08d4, 0x0ed8, 0x0cdc,
0x02e0, 0x00e4, 0x06e8, 0x04ec, 0x0af0, 0x08f4, 0x0ef8, 0x0cfc,
0x0300, 0x0104, 0x0708, 0x050c, 0x0b10, 0x0914, 0x0f18, 0x0d1c,
0x0320, 0x0124, 0x0728, 0x052c, 0x0b30, 0x0934, 0x0f38, 0x0d3c,
0x0340, 0x0144, 0x0748, 0x054c, 0x0b50, 0x0954, 0x0f58, 0x0d5c,
0x0360, 0x0164, 0x0768, 0x056c, 0x0b70, 0x0974, 0x0f78, 0x0d7c,
0x0380, 0x0184, 0x0788, 0x058c, 0x0b90, 0x0994, 0x0f98, 0x0d9c,
0x03a0, 0x01a4, 0x07a8, 0x05ac, 0x0bb0, 0x09b4, 0x0fb8, 0x0dbc,
0x03c0, 0x01c4, 0x07c8, 0x05cc, 0x0bd0, 0x09d4, 0x0fd8, 0x0ddc,
0x03e0, 0x01e4, 0x07e8, 0x05ec, 0x0bf0, 0x09f4, 0x0ff8, 0x0dfc,
};
/*
* Output code to buffer.
*/
int
put_code(code, ent, bfr)
int code, ent;
onebyt *bfr;
{
int lo_byte;
register long mycode;
int bits;
register onebyt *cp; /* opt: points to bfr[s_at_byte] */
bits = bit_tab[(ent >> 8)];
if (((s_at_bit + bits + 7) >> 3) + s_at_byte > BLKSIZ) {
return(-1);
}
mycode = (long)(code & mask[bits]);
#ifdef DEBUG2
fprintf(stderr,"Byte: %d, %lx\n", s_at_byte, mycode);
#endif
/* lo_byte = bfr[s_at_byte] & mask[s_at_bit];*/
cp = bfr + s_at_byte; /* - */
lo_byte = *cp & mask[s_at_bit]; /* - */
if (s_at_bit != 0) {
mycode <<= s_at_bit;
}
/* bfr[s_at_byte++] = (onebyt) lo_byte | (onebyt) (mycode & 0xff);*/
*cp = (onebyt) lo_byte | (onebyt) (mycode & 0xff); /* - */
s_at_byte++, cp++;
/* bfr[s_at_byte] = (onebyt) ((mycode >>= 8) & 0xff);*/
*cp = (onebyt) ((mycode >>= 8) & 0xff); /* - */
if ((s_at_bit += bits) >= 16) {
/* bfr[++s_at_byte] = (char)((mycode >>= 8) & 0xff);*/
cp++, s_at_byte++; /* - */
*cp = (onebyt) ((mycode >>= 8) & 0xff); /* - */
}
s_at_bit &= 0x07;
return(0);
}
/*
* Try LZW compression on the buffer.
*
* Compresses from "buffer" to "outbuf". "inlen" is the #of bytes of data in
* "buffer." Returns the #of bytes of data placed into "outbuf", or -1 on
* failure.
*/
int
do_LZW(bufr, inlen, outbuf)
onebyt *bufr;
int inlen;
onebyt *outbuf;
{
register int index;
register onebyt k;
register onebyt *inbuf, *endbuf;
register struct ht *htp; /* opt: htab[index] */
int ent, prefix, hashdelta;
s_at_byte = 0;
s_at_bit =0;
ent = 0x101;
inbuf = bufr;
endbuf = bufr + inlen;
k = ((char)*inbuf++);
Loop0:
prefix = (int)k;
Loop1:
if (inbuf >= endbuf) {
if (put_code(prefix, ent, outbuf) < 0) {
return(BLKSIZ+2);
}
if (s_at_bit == 0) return(s_at_byte);
else return(s_at_byte+1);
}
k = (onebyt)*inbuf++;
#ifdef OLD_HASH
index = (prefix + (k<<4)) & 0xfff;
#else
index = prefix ^ hashf[k]; /* note index always < 4096 */
#endif
Check_ent:
htp = htab + index;
if (htp->entry == 0) {
/* Entry is 0... */
if (put_code(prefix, ent, outbuf) < 0) {
return(-1); /* failed */
}
htp->entry = ent++;
htp->prefix = prefix;
htp->chr = k;
goto Loop0;
}
else if (htp->prefix == prefix) { /* - */
/* Same prefix... */
if (htp->chr == k) {
/* It's HERE! Yeah! */
prefix = htp->entry;
goto Loop1;
}
goto Sec_hash;
}
/* Check for more...secondary hash on index */
else {
Sec_hash:
#ifdef OLD_HASH
/*index = (index + (unsigned int)(k) + 1) % HSIZE;*/
index += (unsigned int)(k) +1;
if (index >= HSIZE) index -= HSIZE;
#else
hashdelta = (0x120 - k) << 2;
if (index >= hashdelta)
index -= hashdelta;
else
index += (HSIZE - hashdelta);
#endif
#ifdef DEBUG2
fprintf(stderr,"New ind: %d, k=%d\n", index, (unsigned int)k);
#endif
goto Check_ent;
}
}
/*
* Clear out the hash table.
*/
void
ClearTab()
{
register int i;
register struct ht *htp; /* opt: htab[i] */
/* for(i=0; i < HSIZE; i++)*/
/* htab[i].entry = 0;*/
htp = htab; /* - */
for (i = HSIZE; i; htp++, i--) /* - */
htp->entry = 0; /* - */
}
/*
* Do run-length encoding
*
* Takes input from srcptr, and writes to dstptr. Maximum expansion is
* (BLKSIZ / 2) + (BLKSIZ / 2) * 3 == 2 * BLKSIZ
* Output of form <DLE> char count where count is #of bytes -1.
*
* This really isn't very pretty, but it works.
*/
int
do_RLE(srcptr, dstptr)
register onebyt *srcptr, *dstptr;
{
#define ALT_RLE /* testing */
#ifndef ALT_RLE
register int found, scount /*, dcount*/;
register onebyt c, lastc, tlastc;
onebyt *dststart = dstptr;
c = *(srcptr++); scount = 1;
/*dcount = 0;*/
found = 1; /* one char has been found */
lastc = '\0';
while (scount < BLKSIZ) {
tlastc = lastc;
lastc = c;
c = *(srcptr++); scount++;
if (found == 1) { /* no run found */
if (c != lastc) { /* no run starting */
if (lastc == ESCAPE_CHAR) {
*(dstptr++) = ESCAPE_CHAR; /*dcount++;*/
*(dstptr++) = lastc; /*dcount++;*/
*(dstptr++) = 0; /*dcount++;*/ /* found one */
} else {
*(dstptr++) = lastc; /*dcount++;*/
}
found = 1;
} else {
found = 2; /* they matched, so two in a row */
}
} else if (found == 2) { /* got two, try for three */
if (c != lastc) { /* only got two in a row */
if (lastc == ESCAPE_CHAR) { /* and tlastc as well */
*(dstptr++) = ESCAPE_CHAR; /*dcount++;*/
*(dstptr++) = lastc; /*dcount++;*/
*(dstptr++) = 1; /*dcount++;*/ /* found two */
} else {
*(dstptr++) = tlastc; /*dcount++;*/
*(dstptr++) = lastc; /*dcount++;*/
}
found = 1;
} else { /* found 3, got a run going */
found = 3;
}
} else { /* (found >= 3), got a run going */
if (c == lastc) { /* found another */
found++;
}
if ((c != lastc) || (found > 256)) { /* end, or too many */
*(dstptr++) = ESCAPE_CHAR; /*dcount++;*/
*(dstptr++) = lastc; /*dcount++;*/
*(dstptr++) = (found > 256) ? 255 : found-1;
/*dcount++;*/
found = 1; /* c has something other than the run char */
/* or found is 257-256 = 1 */
}
}
} /* while */
/* reached end of buffer; flush what was left */
if (found == 1) {
if (c == ESCAPE_CHAR) {
*(dstptr++) = ESCAPE_CHAR; /*dcount++;*/
*(dstptr++) = c; /*dcount++;*/
*(dstptr++) = 0; /*dcount++;*/
} else {
*(dstptr++) = c; /*dcount++;*/
}
} else if (found == 2) {
/* maybe have if lastc == c == ESCAPE_CHAR? */
if (lastc == ESCAPE_CHAR) {
*(dstptr++) = ESCAPE_CHAR; /*dcount++;*/
*(dstptr++) = lastc; /*dcount++;*/
*(dstptr++) = 0; /*dcount++;*/
} else {
*(dstptr++) = lastc; /*dcount++;*/
}
if (c == ESCAPE_CHAR) {
*(dstptr++) = ESCAPE_CHAR; /*dcount++;*/
*(dstptr++) = c; /*dcount++;*/
*(dstptr++) = 0; /*dcount++;*/
} else {
*(dstptr++) = c; /*dcount++;*/
}
} else { /* found >= 3, in the middle of processing a run */
*(dstptr++) = ESCAPE_CHAR; /*dcount++;*/
*(dstptr++) = c; /*dcount++;*/
*(dstptr++) = found-1; /*dcount++;*/
}
/* return (dcount);*/
return (dstptr - dststart);
#else /*ALT_RLE*/
/*
* This was an attempt to write a faster do_RLE routine. However,
* the profiler on my machine showed it to be slower than the big
* wad of stuff above. I decided to leave the code here in case somebody
* wants to play with it.
*/
register onebyt *scanptr;
onebyt *endptr, *dststart;
register onebyt c;
register int i, count;
endptr = srcptr + BLKSIZ; /* where the source ends */
dststart = dstptr; /* where the destination begins */
while (srcptr < endptr) {
c = *srcptr;
scanptr = srcptr+1;
count = 1;
while (*scanptr == c && scanptr < endptr)
scanptr++, count++;
if (count > 3) {
i = count;
do {
*(dstptr++) = ESCAPE_CHAR;
*(dstptr++) = c;
if (i > 256) { /* was count */
*(dstptr++) = 255;
i -= 256;
} else {
*(dstptr++) = i-1; /* was count-1 */
break;
}
} while (i > 0);
} else {
if (c == ESCAPE_CHAR) { /* special case: 1-3 0xDBs */
*(dstptr++) = ESCAPE_CHAR;
*(dstptr++) = ESCAPE_CHAR;
*(dstptr++) = count-1; /* count == 0 is legal */
} else {
i = count;
while (i--)
*(dstptr++) = c;
}
}
srcptr += count;
}
#ifdef DEBUG
if (srcptr > endptr)
printf("BUG: srcptr > endptr in do_RLE\n");
#endif
return (dstptr - dststart);
#endif /*ALT_RLE*/
}
/*
* Main compression entry point.
*
* Returns actual thread_format used.
*
* Note that "copybuf" should be at least twice as big as BLKSIZ.
*/
long
pak_SHK(srcfd, dstfd, length, copybuf)
int srcfd, dstfd;
long length; /* uncompressed size */
onebyt *copybuf;
{
unsigned int partial; /* size for partial read/write */
onebyt *rptr, *out_buf;
register int idx;
onebyt scratch[8];
long srcposn, /* start in source file */
startposn, /* start in dest file */
endposn; /* end in dest file */
long unc_len = length,
comp_len = 0L;
twobyt CRC;
int rlesize, lzwsize, out_size; /* length after compression */
int sc; /* spin counter */
static char *procName = "pak_SHK";
if (htab == NULL)
htab = (struct ht *) Malloc(HSIZE * sizeof(struct ht));
CRC = 0;
if ((srcposn = lseek(srcfd, (off_t) 0, S_REL)) < 0) /* only used if */
Fatal("Bad seek (srcposn)", procName); /* compress fails */
if ((startposn = lseek(dstfd, (off_t) 0, S_REL)) < 0)
Fatal("Bad seek (startposn)", procName);
lseek(dstfd, (off_t) 4, S_REL); /* leave room for 4-byte header */
comp_len += 4L;
sc = 0;
do { /* have to handle when length == 0L */
if (length > (long) BLKSIZ) {
partial = (unsigned int) BLKSIZ;
length -= (long) BLKSIZ;
} else {
partial = (unsigned int) length;
length = 0L;
for (idx = partial; idx < BLKSIZ; idx++) /* fill in zeroes */
*(copybuf + idx) = 0;
}
if (partial > 0) { /* should work anyway, but let's be careful */
if (read(srcfd, copybuf, partial) != partial)
Fatal("Source read failed", procName);
}
/* calc CRC on all 4096 bytes */
CRC = CalcCRC(CRC, (onebyt *) copybuf, BLKSIZ);
rlesize = do_RLE(copybuf, copybuf + BLKSIZ+1); /* pack 4096 bytes */
if (rlesize < 0x1000) { /* did it pack or expand? */
rptr = copybuf + BLKSIZ+1; /* use packed version */
} else {
rlesize = 0x1000; /* just store original */
rptr = copybuf;
}
ClearTab();
lzwsize = do_LZW(rptr, rlesize, lbuf); /* compress from rle to lzw */
if ((lzwsize > rlesize) || (lzwsize < 0)) {
/* lzw failed, use rle'd copy */
scratch[2] = 0;
out_size = rlesize;
out_buf = rptr;
} else {
/* lzw succeeded, use it */
scratch[2] = 1; /* LZW on */
out_size = lzwsize;
out_buf = lbuf;
}
scratch[0] = (onebyt) (rlesize & 0x00ff); /* NOT out_size */
scratch[1] = (onebyt) ((rlesize >> 8) & 0x00ff);
if (write(dstfd, scratch, 3) != 3)
Fatal("Dest hdr write failed", procName);
comp_len += 3;
comp_len += out_size;
if (comp_len > unc_len)
goto bad_compress; /* you didn't see this */
if (write(dstfd, out_buf, out_size) != out_size) /* need to do CRLF */
Fatal("Dest write failed", procName);
sc++;
if (sc == 15) {
sc = 0;
Spin();
}
} while (length != 0L);
if ((endposn = lseek(dstfd, (off_t) 0, S_REL)) < 0)
Fatal("Bad seek (now)", procName);
if (lseek(dstfd, (off_t) startposn, S_ABS) < 0)
Fatal("Bad seek (to4)", procName);
scratch[0] = (char) CRC;
scratch[1] = (char) (CRC >> 8);
scratch[2] = 0;
scratch[3] = ESCAPE_CHAR;
if (write(dstfd, scratch, 4) != 4)
Fatal("Dest hdr write failed", procName);
if (lseek(dstfd, (off_t) endposn, S_ABS) < 0)
Fatal("Bad seek (last)", procName);
if (comp_len != endposn - startposn) {
printf(
"internal error: comp_len=%ld, endposn=%ld, startposn=%ld (%ld)\n",
comp_len, endposn, startposn, endposn - startposn);
}
packedSize = comp_len;
return (0x0002); /* SHK packing */
bad_compress: /* I'm too lazy to do a procedure call... */
if (verbose) { printf("storing..."); fflush(stdout); }
if (lseek(srcfd, (off_t) srcposn, S_ABS) < 0)
Fatal("Bad seek (srcposn in bad_compress)", procName);
if (lseek(dstfd, (off_t) startposn, S_ABS) < 0)
Fatal("Bad seek (startposn in bad_compress)", procName);
FCopy(srcfd, dstfd, unc_len, copybuf, FALSE);
packedSize = unc_len;
return (0x0000); /* no compression */
}
/*
* P8 ShrinkIt uncompression routines
*
* Copyright 1989 Kent Dickey
* C translation by Kent Dickey / Andy McFadden
* Modifications for LZW-II designed by Andy Nicholas
*
* C decoder for LZW-II by Frank Petroski / Kent Dickey (simultaneously
* and independently). Speed optimizations by Kent Dickey.
*/
/*static int inf; /* to make Getc() calls happy */
static BOOLEAN type2; /* true if working with LZW-II format */
static onebyt escape_char;
typedef struct {
unsigned char chr;
int prefix;
} Table_ent;
static Table_ent Real_tab[BLKSIZ-256]; /* first 256 don't exist */
static Table_ent *Table;
static int Mask_tab[17] = {
0x0000, 0x01ff, 0x03ff, 0x03ff, 0x07ff,
0x07ff, 0x07ff, 0x07ff, 0x0fff, 0x0fff,
0x0fff, 0x0fff, 0x0fff, 0x0fff, 0x0fff,
0x0fff, 0x0fff
};
static int Number[17] = {
/* 0,1,2,2,3,3,3,3,4,4,4,4,4,4,4,4,4 };*/
8,9,10,10,11,11,11,11,12,12,12,12,12,12,12,12,12 };
static onebyt *Stack; /* simulated stack <= 64 for LZW-I, <= 4096 for II */
static int out_bytes, stack_ptr, entry, at_bit, at_byte;
static onebyt last_byte; /* used in get_code */
static int reset_fix; /* fix problem unpacking certain LZW-II archives */
/* fake getc() */
# define Getc() *(ibuf++)
/*
* Stack operations; used by undo_LZW and undo_LZW_2
*/
#ifdef DEBUG
# define push(a_byte) \
{ \
if (stack_ptr - Stack > 4096) { \
printf("\n*** stack_ptr exceeded 4096 in push() [%d]\n", \
(int) (stack_ptr - Stack));\
exit (-1); \
} \
*(stack_ptr++) = (onebyt) a_byte; \
}
#else
# define push(a_byte) *(stack_ptr++) = (onebyt) a_byte;
#endif
#ifdef DEBUG
# define dump_stack(buffer) \
{ \
printf("--- Going to dump stack, stack_ptr = %d, out_bytes = %d\n", \
(int) (stack_ptr - Stack), out_bytes); \
while (stack_ptr-- > stack_start) { \
*(buffer++) = *stack_ptr; \
} \
}
#else
# define dump_stack(buffer) \
while (stack_ptr-- > stack_start) { \
*(buffer++) = *stack_ptr; \
}
#endif
/*
* Decipher LZW codes.
*/
int
get_code()
{
register unsigned int num_bits, old_bit, last_bit;
long value, mask;
/* onebyt byte1, byte2, byte3;*/ /* get compressed chars... */
long byte1, byte2, byte3; /* - */
#ifdef DEBUG
printf("ENT: bit=%d byte=%-4d last_byte=$%.2x ",
at_bit, at_byte, last_byte);
printf("Entry: %.4x \n", entry);
#endif
num_bits = ((entry+1) >> 8); /* get hi-byte of entry */
/* last_bit = at_bit + Number[num_bits] + 8;*/
last_bit = at_bit + Number[num_bits];
old_bit = at_bit;
#ifdef DEBUG
if (at_byte >= BLKSIZ) {
fprintf(stderr, "at_byte exceeded BLKSIZ (4096) in get_code()\n");
exit (-1);
}
#endif
if (at_bit == 0)
last_byte = Getc();
/* byte1 = last_byte;*/ /* first byte = last one used */
byte1 = (long) last_byte; /* - */
last_byte = Getc(); /* - */
/* byte2 = Getc(inf);*/
byte2 = ((long) last_byte) << 8; /* - */
if (last_bit > 16) { /* get 3rd byte if nec. */
/* byte3 = Getc(inf);*/
/* last_byte = byte3;*/
last_byte = Getc(); /* - */
byte3 = ((long) last_byte) << 16; /* - */
} else {
byte3 = 0;
/* last_byte = byte2;*/
}
/* value = ((((long)byte3 << 8) + (long)byte2) << 8) + (long)byte1;*/
value = byte3 + byte2 + byte1; /* - */
mask = (long) Mask_tab[num_bits];
at_byte += (last_bit >> 3); /* new byte */
at_bit = (last_bit & 0x07);
#ifdef DEBUG
printf("| EX: value=$%.6x mask=$%.4x return=$%.3x\n",
value, mask, ((value >> old_bit) & mask));
#endif
#ifdef ZERO_SHIFT_BAD
if (old_bit)
return ((value >> old_bit) & mask);
else
return (value & mask); /* shifting by zero may be undefined */
#else
return ((value >> old_bit) & mask);
#endif /*ZERO_SHIFT_BAD*/
}
/*
* Un-LZW a range of bytes
*
* Reads data with get_code() and stores the output in "buffer".
*/
void
undo_LZW(buffer, length)
unsigned char *buffer; /* where to put output */
int length; /* uncompressed length of output */
{
register int oldc, incode, finalc, ptr;
register onebyt *endbuf, *stack_ptr, *stack_start;
/* initialize variables */
Table = Real_tab-256;
entry = 0x101; /* start at $101 */
at_bit = at_byte = 0;
endbuf = buffer + length;
stack_start = stack_ptr = Stack;
last_byte = 0; /* init last_byte */
oldc = incode = get_code(/*buffer*/);
finalc = (oldc & 0xff);
*(buffer++) = (onebyt) incode;
/* main loop */
while (buffer < endbuf) {
incode = ptr = get_code(/*buffer*/);
if (ptr >= entry) { /* handle KwKwK case */
push(finalc);
ptr = oldc;
}
while (ptr > 0xff) { /* fill the stack */
push(Table[ptr].chr);
ptr = Table[ptr].prefix;
}
/* ptr is now < 0x100 */
finalc = ptr;
*(buffer++) = (onebyt) finalc;
while (stack_ptr > stack_start) /* dump the stack */
*(buffer++) = *(--stack_ptr);
Table[entry].chr = (finalc & 0xff); /* mask to get unsigned?? byte */
Table[entry].prefix = oldc;
entry++;
oldc = incode;
}
}
/*
* Un-LZW-II a range of bytes
*
* Reads data with get_code() and stores the output in "buffer". Has
* additional code to support LZW-II's table clears.
*/
void
undo_LZW_2(buffer, length)
unsigned char *buffer; /* where to put output */
int length; /* uncompressed length of output */
{
register int oldc, incode, finalc, ptr;
register onebyt *endbuf, *stack_ptr, *stack_start;
/* initialize variables */
at_bit = at_byte = 0;
/* out_bytes = 0;*/
/* stack_ptr = 0;*/
endbuf = buffer + length;
stack_start = stack_ptr = Stack;
last_byte = 0; /* init last_byte */
/* main loop */
/* while (out_bytes < length) {*/
while (buffer < endbuf) { /* - */
if (entry == 0x101 && !reset_fix) { /* table is really empty */
oldc = incode = get_code(/*buffer*/);
finalc = (oldc & 0xff);
/* *(buffer + out_bytes++) = (unsigned char) incode;*/
*(buffer++) = (onebyt) incode; /* - */
if (buffer >= endbuf) { /* buffer is full? If so, we */
reset_fix = 1; /* want to skip get_code() next time */
break; /* we come through for next chunk */
}
}
incode = ptr = get_code(/*buffer*/);
if (incode == 0x100) { /* Clear table code */
entry = 0x101; /* start at $101 */
Table = Real_tab-256;
reset_fix = 0;
continue;
}
if (ptr >= entry) {
push(finalc);
ptr = oldc;
}
while (ptr > 0xff) {
push(Table[ptr].chr);
ptr = Table[ptr].prefix;
}
/* ptr is now < 0x100 */
finalc = ptr;
/* push(finalc);*/
/* dump_stack(buffer);*/
*(buffer++) = (onebyt) finalc; /* - */
while (stack_ptr > stack_start) /* - */
*(buffer++) = *(--stack_ptr); /* - */
Table[entry].chr = (finalc & 0xff); /* mask to get unsigned?? byte */
Table[entry].prefix = oldc;
entry++;
oldc = incode;
}
}
/*
* Second pass... undo the Run Length Encoding.
*
* Copy data from inbuffer to outbuffer. Keep going until we've got
* exactly BLKSIZ bytes. Note that this uses codes of the form
* <DLE> char count
* which is different from some other programs.
*/
void
undo_RLE(inbuffer, outbuffer)
unsigned char *inbuffer, *outbuffer;
/*int length; /* how many bytes from LZW; just to make sure... */
{
register onebyt c;
register int count; /* count is RLE reps */
register onebyt *outbufend;
#ifdef DEBUG
/*printf("Starting undo_RLE, length = %d\n", length);*/
#endif
outbufend = outbuffer + BLKSIZ;
while (outbuffer < outbufend) {
c = *(inbuffer++); /*length--;*/
if (c == (onebyt) escape_char) {
c = *(inbuffer++); /*length--;*/
count = *(inbuffer++); /*length--;*/
while (count-- >= 0) {
*(outbuffer++) = c; /*Putc(c, outf);*/
}
} else {
*(outbuffer++) = c; /*Putc(c, outf);*/
}
}
if (outbuffer != outbufend)
fprintf(stderr, "internal error: bad undo_RLE\n");
#ifdef DEBUG
/* printf("Exiting undo_RLE, length = %d (should be 0), total = %d (4096)\n",
length, outbufend-outbuffer);*/
#endif
}
/*
* Main entry point.
*
* This is among the more hellish things I've written. Uses
* a large buffer for efficiency reasons, and unpacks a stream of bytes.
*
* If you find this hard to understand, imagine what it was like to debug.
*/
void
unpak_SHK(srcfd,dstfd,comp_thread_eof,thread_eof,buffer, use_type2, thread_crc)
int srcfd, dstfd;
fourbyt comp_thread_eof, thread_eof;
register onebyt *buffer;
BOOLEAN use_type2; /* true if we should expect LZW-II */
twobyt thread_crc;
{
twobyt CRC, blkCRC;
onebyt vol;
onebyt *wrbuf; /* points to buffer we're about to write */
short unlen, lzwflag, rleflag, complen; /* should be short */
unsigned int partial, toread, still_in_buf /*, crcsize*/;
fourbyt tmp4; /* temporary 4-byte variable */
int cc;
static char *procName = "unpak_SHK";
if (Stack == NULL)
Stack = (onebyt *) Malloc(4096);
type2 = use_type2;
if (type2)
CRC = 0xffff; /* different CRC for LZW-II */
else
CRC = 0;
/* initialize variables for LZW-II */
Table = Real_tab-256;
entry = 0x101; /* start at $101 */
reset_fix = 0;
/* read min(PAKBUFSIZ, comp_thread_eof) bytes into buffer */
if (comp_thread_eof > (fourbyt) PAKBUFSIZ) {
toread = (unsigned int) PAKBUFSIZ;
comp_thread_eof -= (fourbyt) PAKBUFSIZ;
} else {
toread = (unsigned int) comp_thread_eof; /* read it all... */
comp_thread_eof = (fourbyt) 0;
}
/* do initial read */
#ifdef DEBUG1
printf("initial read = %u\n", toread);
#endif
if ((cc = read(srcfd, buffer, toread)) < toread) {
#ifdef DEBUG1
printf("Only read %d bytes\n", cc);
#endif
Fatal("Bad read during uncompress", procName);
}
ibuf = buffer; /* set input pointer to start of buffer */
/* get header data */
if (type2) {
blkCRC = thread_crc;
} else {
blkCRC = Getc();
blkCRC += (Getc() << 8);
}
vol = (char) Getc(); /* disk volume #; not used here */
escape_char = (char) Getc(); /* RLE delimiter */
#ifdef DEBUG1
printf("vol = %d, escape_char = %x\n", vol, escape_char);
#endif
/*
* main loop
*/
while (thread_eof != (fourbyt) 0) {
/* note "unlen" is un-LZWed length (i.e., after RLE) */
if (type2) {
unlen = Getc();
unlen += (Getc() << 8);
lzwflag = (unlen & 0x8000) ? 1 : 0; /* flag is hi bit */
unlen &= 0x1fff; /* strip extra stuff */
rleflag = (unlen != BLKSIZ);
if (lzwflag) { /* will the real length bytes please stand up*/
complen = Getc();
complen += (Getc() << 8);
}
} else {
unlen = Getc();
unlen += (Getc() << 8);
lzwflag = Getc();
rleflag = (unlen != BLKSIZ);
}
#ifdef DEBUG1
printf("Length after RLE = %d ($%.4x)\n", unlen, unlen);
printf("LZW flag = %d, RLE flag = %d\n", lzwflag, rleflag);
if (lzwflag != 0 && lzwflag != 1) { /* this is weird... */
for (lzwflag = -6; lzwflag < 3; lzwflag++) {
printf("foo %d: %.2x\n", lzwflag, *(ibuf+lzwflag));
}
}
if (type2 && lzwflag) {
printf("Length after RLE+LZW = %d ($%.4x)\n", complen, complen);
}
#endif
/* If it looks like we're going to run out of room, shift & read
/* Mostly a guess; LZW length is less than unlen... This is
/* complicated and very prone to errors (but we err on the safe side).
/* tmp4 is the number of bytes between the current ptr and the end;
/* some (16-bit) compilers yack if it's all one statement.*/
tmp4 = (fourbyt) buffer + (fourbyt) PAKBUFSIZ;
tmp4 -= (fourbyt) ibuf;
if (tmp4 < (unlen + 6)) { /* 6 = 3/4 byte header + two just in case */
still_in_buf = tmp4;
#ifdef DEBUG1
printf("--- unlen = %d, space left = %d bytes\n",
unlen, still_in_buf);
#endif
/* BCopy((onebyt *) ibuf, (onebyt *) buffer, still_in_buf, FALSE);*/
BCOPY((onebyt *) ibuf, (onebyt *) buffer, still_in_buf);
if (comp_thread_eof != (fourbyt) 0) { /* no read, just shift */
if (comp_thread_eof > ((fourbyt) PAKBUFSIZ - still_in_buf)){
toread = (unsigned int) PAKBUFSIZ - still_in_buf;
comp_thread_eof -= (fourbyt) PAKBUFSIZ - still_in_buf;