home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Crawly Crypt Collection 1
/
crawlyvol1.bin
/
program
/
grfx_snd
/
tifflib
/
source
/
tif_sgi.c
< prev
next >
Wrap
C/C++ Source or Header
|
1992-11-10
|
9KB
|
239 lines
#pragma warn -use
static char *sccsid = "@(#)TIFF/tif_sgi.c 1.06, Copyright (c) Sam Leffler, Dieter Linde, "__DATE__;
#pragma warn .use
/*
* Copyright (c) 1988, 1990 by Sam Leffler, Oct 8 1990
* All rights reserved.
*
* This file is provided for unrestricted use provided that this legend is included on all tape media and as a part of the
* software program in whole or part. Users may copy, modify or distribute this file at will.
*
* TIFF Library.
*
* SGI RLE Compression Algorithm Support
*/
#include "tiffio.h"
#define MAXRUN 126 /* max length of a run */
#define LITBIT 0x80 /* bit indicating a literal string */
/****************************************************************************
* Encode a scanline of pixels (this is basically the PackBits encoding).
*/
static int
SGIEncode(
TIFF *tif,
u_char *bp,
register int cc
)
{
register char *op, *lastliteral;
register int n, b;
enum {
BASE,
LITERAL,
RUN,
LITERAL_RUN
} state;
char *ep;
int slop;
/*** XXX 16 bits/sample case ***/
op = (char *)tif->tif_rawcp;
ep = (char *)(tif->tif_rawdata + tif->tif_rawdatasize);
state = BASE;
lastliteral = 0;
while (cc > 0) {
/*
* Find the longest string of identical bytes.
*/
b = *bp++;
cc--;
n = 1;
for (; cc > 0 && b == *bp; cc--, bp++)
n++;
again:
if (op + 2 >= ep) { /* insure space for new data */
/*
* Be careful about writing the last literal. Must write up to that point
* and then copy the remainder to the front of the buffer.
*/
if (state == LITERAL || state == LITERAL_RUN) {
slop = (int)(op - lastliteral);
tif->tif_rawcc += ((u_char *)lastliteral - tif->tif_rawcp);
if (!TIFFFlushData(tif))
return(-1);
op = (char *)tif->tif_rawcp;
for (; slop-- > 0; *op++ = *lastliteral++)
;
lastliteral = (char *)tif->tif_rawcp;
}
else {
tif->tif_rawcc += ((u_char *)op - tif->tif_rawcp);
if (!TIFFFlushData(tif))
return(-1);
op = (char *)tif->tif_rawcp;
}
}
switch (state) {
case BASE: /* initial state, set run/literal */
if (n > 1) {
state = RUN;
if (n > MAXRUN) {
*op++ = MAXRUN;
*op++ = b;
n -= MAXRUN;
goto again;
}
*op++ = n;
*op++ = b;
}
else {
lastliteral = op;
*op++ = 1;
*op++ = b;
state = LITERAL;
}
break;
case LITERAL: /* last object was literal string */
if (n > 1) {
state = LITERAL_RUN;
if (n > MAXRUN) {
*op++ = MAXRUN;
*op++ = b;
n -= MAXRUN;
goto again;
}
*op++ = n; /* encode run */
*op++ = b;
}
else { /* extend literal */
if (++(*lastliteral) == MAXRUN) {
*lastliteral |= LITBIT;
state = BASE;
}
*op++ = b;
}
break;
case RUN: /* last object was run */
if (n > 1) {
if (n > MAXRUN) {
*op++ = MAXRUN;
*op++ = b;
n -= MAXRUN;
goto again;
}
*op++ = n;
*op++ = b;
}
else {
lastliteral = op;
*op++ = 1;
*op++ = b;
state = LITERAL;
}
break;
case LITERAL_RUN: /* literal followed by a run */
/*
* Check to see if previous run should be converted to a literal, in which
* case we convert literal-run-literal to a single literal.
*/
if (n == 1 && op[-2] == (char)-1 && *lastliteral < MAXRUN - 2) {
if ((*lastliteral += 2) == MAXRUN) {
*lastliteral |= LITBIT;
state = BASE;
}
else
state = LITERAL;
op[-2] = op[-1]; /* replicate */
}
else {
*lastliteral |= LITBIT;
state = RUN;
}
goto again;
}
}
if (state == LITERAL || state == LITERAL_RUN)
*lastliteral |= LITBIT;
tif->tif_rawcc += ((u_char *)op - tif->tif_rawcp);
tif->tif_rawcp = (u_char *)op;
return(1);
}
#define DECODE(cc, bp, occ, op, size) while (cc > 0 && occ > 0) { \
pixel = *bp++; \
cc--; \
n = pixel &~ LITBIT; \
if (n == 0) \
continue; \
if (pixel & LITBIT) { \
bcopy(bp, op, size * n); \
op += size * n; \
occ -= size * n; \
bp += size * n; \
cc -= size * n; \
} \
else { \
pixel = *bp++; \
cc--; \
occ -= size * n; \
while (n-- > 0) \
*op++ = pixel; \
} \
}
/****************************************************************************
*
*/
static int
SGIDecode(
TIFF *tif,
u_char *buf,
register int occ
)
{
register int n, pixel;
register long cc;
cc = tif->tif_rawcc;
if (tif->tif_dir.td_bitspersample <= 8) {
register u_char *bp, *op;
bp = (u_char *)tif->tif_rawcp;
op = buf;
DECODE(cc, bp, occ, op, (int)sizeof(char));
tif->tif_rawcp = bp;
}
else {
register u_short *bp, *op;
bp = (u_short *)tif->tif_rawcp;
op = (u_short *)buf;
DECODE(cc, bp, occ, op, (int)sizeof(short));
tif->tif_rawcp = (u_char *)bp;
}
tif->tif_rawcc = cc;
if (occ > 0) {
TIFFError(tif->tif_name, "SGIDecode: Not enough data for scanline %d", tif->tif_row);
return(0);
}
return(1);
}
/****************************************************************************
*
*/
int
TIFFInitSGI(
TIFF *tif
)
{
tif->tif_decoderow = SGIDecode;
tif->tif_encoderow = SGIEncode;
return(1);
}