tif_swab.c

一个国人自己实现图像库的程序（有参考价值）

/* $Header: /cvsroot/osrs/libtiff/libtiff/tif_swab.c,v 1.1.1.1 1999/07/27 21:50:27 mike Exp $ */

/*
 * Copyright (c) 1988-1997 Sam Leffler
 * Copyright (c) 1991-1997 Silicon Graphics, Inc.
 *
 * Permission to use, copy, modify, distribute, and sell this software and 
 * its documentation for any purpose is hereby granted without fee, provided
 * that (i) the above copyright notices and this permission notice appear in
 * all copies of the software and related documentation, and (ii) the names of
 * Sam Leffler and Silicon Graphics may not be used in any advertising or
 * publicity relating to the software without the specific, prior written
 * permission of Sam Leffler and Silicon Graphics.
 * 
 * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND, 
 * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY 
 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.  
 * 
 * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
 * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
 * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
 * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF 
 * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE 
 * OF THIS SOFTWARE.
 */

/*
 * TIFF Library Bit & Byte Swapping Support.
 *
 * XXX We assume short = 16-bits and long = 32-bits XXX
 */
#include "tiffiop.h"

#ifndef TIFFSwabShort
void
TIFFSwabShort(uint16* wp)
{
	register u_char* cp = (u_char*) wp;
	int t;

	t = cp[1]; cp[1] = cp[0]; cp[0] = t;
}
#endif

#ifndef TIFFSwabLong
void
TIFFSwabLong(uint32* lp)
{
	register u_char* cp = (u_char*) lp;
	int t;

	t = cp[3]; cp[3] = cp[0]; cp[0] = t;
	t = cp[2]; cp[2] = cp[1]; cp[1] = t;
}
#endif

#ifndef TIFFSwabArrayOfShort
void
TIFFSwabArrayOfShort(uint16* wp, register u_long n)
{
	register u_char* cp;
	register int t;

	/* XXX unroll loop some */
	while (n-- > 0) {
		cp = (u_char*) wp;
		t = cp[1]; cp[1] = cp[0]; cp[0] = t;
		wp++;
	}
}
#endif

#ifndef TIFFSwabArrayOfLong
void
TIFFSwabArrayOfLong(register uint32* lp, register u_long n)
{
	register unsigned char *cp;
	register int t;

	/* XXX unroll loop some */
	while (n-- > 0) {
		cp = (unsigned char *)lp;
		t = cp[3]; cp[3] = cp[0]; cp[0] = t;
		t = cp[2]; cp[2] = cp[1]; cp[1] = t;
		lp++;
	}
}
#endif

#ifndef TIFFSwabDouble
void
TIFFSwabDouble(double *dp)
{
        register uint32* lp = (uint32*) dp;
        uint32 t;

	TIFFSwabArrayOfLong(lp, 2);
	t = lp[0]; lp[0] = lp[1]; lp[1] = t;
}
#endif

#ifndef TIFFSwabArrayOfDouble
void
TIFFSwabArrayOfDouble(double* dp, register u_long n)
{
	register uint32* lp = (uint32*) dp;
        register uint32 t;

	TIFFSwabArrayOfLong(lp, n + n);
        while (n-- > 0) {
		t = lp[0]; lp[0] = lp[1]; lp[1] = t;
                lp += 2;
        }
}
#endif

/*
 * Bit reversal tables.  TIFFBitRevTable[<byte>] gives
 * the bit reversed value of <byte>.  Used in various
 * places in the library when the FillOrder requires
 * bit reversal of byte values (e.g. CCITT Fax 3
 * encoding/decoding).  TIFFNoBitRevTable is provided
 * for algorithms that want an equivalent table that
 * do not reverse bit values.
 */
static const unsigned char TIFFBitRevTable[256] = {
    0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0,
    0x10, 0x90, 0x50, 0xd0, 0x30, 0xb0, 0x70, 0xf0,
    0x08, 0x88, 0x48, 0xc8, 0x28, 0xa8, 0x68, 0xe8,
    0x18, 0x98, 0x58, 0xd8, 0x38, 0xb8, 0x78, 0xf8,
    0x04, 0x84, 0x44, 0xc4, 0x24, 0xa4, 0x64, 0xe4,
    0x14, 0x94, 0x54, 0xd4, 0x34, 0xb4, 0x74, 0xf4,
    0x0c, 0x8c, 0x4c, 0xcc, 0x2c, 0xac, 0x6c, 0xec,
    0x1c, 0x9c, 0x5c, 0xdc, 0x3c, 0xbc, 0x7c, 0xfc,
    0x02, 0x82, 0x42, 0xc2, 0x22, 0xa2, 0x62, 0xe2,
    0x12, 0x92, 0x52, 0xd2, 0x32, 0xb2, 0x72, 0xf2,
    0x0a, 0x8a, 0x4a, 0xca, 0x2a, 0xaa, 0x6a, 0xea,
    0x1a, 0x9a, 0x5a, 0xda, 0x3a, 0xba, 0x7a, 0xfa,
    0x06, 0x86, 0x46, 0xc6, 0x26, 0xa6, 0x66, 0xe6,
    0x16, 0x96, 0x56, 0xd6, 0x36, 0xb6, 0x76, 0xf6,
    0x0e, 0x8e, 0x4e, 0xce, 0x2e, 0xae, 0x6e, 0xee,
    0x1e, 0x9e, 0x5e, 0xde, 0x3e, 0xbe, 0x7e, 0xfe,
    0x01, 0x81, 0x41, 0xc1, 0x21, 0xa1, 0x61, 0xe1,
    0x11, 0x91, 0x51, 0xd1, 0x31, 0xb1, 0x71, 0xf1,
    0x09, 0x89, 0x49, 0xc9, 0x29, 0xa9, 0x69, 0xe9,
    0x19, 0x99, 0x59, 0xd9, 0x39, 0xb9, 0x79, 0xf9,
    0x05, 0x85, 0x45, 0xc5, 0x25, 0xa5, 0x65, 0xe5,
    0x15, 0x95, 0x55, 0xd5, 0x35, 0xb5, 0x75, 0xf5,
    0x0d, 0x8d, 0x4d, 0xcd, 0x2d, 0xad, 0x6d, 0xed,
    0x1d, 0x9d, 0x5d, 0xdd, 0x3d, 0xbd, 0x7d, 0xfd,
    0x03, 0x83, 0x43, 0xc3, 0x23, 0xa3, 0x63, 0xe3,
    0x13, 0x93, 0x53, 0xd3, 0x33, 0xb3, 0x73, 0xf3,
    0x0b, 0x8b, 0x4b, 0xcb, 0x2b, 0xab, 0x6b, 0xeb,
    0x1b, 0x9b, 0x5b, 0xdb, 0x3b, 0xbb, 0x7b, 0xfb,
    0x07, 0x87, 0x47, 0xc7, 0x27, 0xa7, 0x67, 0xe7,
    0x17, 0x97, 0x57, 0xd7, 0x37, 0xb7, 0x77, 0xf7,
    0x0f, 0x8f, 0x4f, 0xcf, 0x2f, 0xaf, 0x6f, 0xef,
    0x1f, 0x9f, 0x5f, 0xdf, 0x3f, 0xbf, 0x7f, 0xff
};
static const unsigned char TIFFNoBitRevTable[256] = {
    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 
    0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 
    0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 
    0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 
    0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 
    0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 
    0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 
    0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, 
    0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 
    0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, 
    0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 
    0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f, 
    0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 
    0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 
    0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 
    0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, 
    0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 
    0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, 
    0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 
    0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f, 
    0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7, 
    0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf, 
    0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, 
    0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf, 
    0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, 
    0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf, 
    0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 
    0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf, 
    0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 
    0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef, 
    0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 
    0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff, 
};

const unsigned char*
TIFFGetBitRevTable(int reversed)
{
	return (reversed ? TIFFBitRevTable : TIFFNoBitRevTable);
}

void
TIFFReverseBits(register u_char* cp, register u_long n)
{
	for (; n > 8; n -= 8) {
		cp[0] = TIFFBitRevTable[cp[0]];
		cp[1] = TIFFBitRevTable[cp[1]];
		cp[2] = TIFFBitRevTable[cp[2]];
		cp[3] = TIFFBitRevTable[cp[3]];
		cp[4] = TIFFBitRevTable[cp[4]];
		cp[5] = TIFFBitRevTable[cp[5]];
		cp[6] = TIFFBitRevTable[cp[6]];
		cp[7] = TIFFBitRevTable[cp[7]];
		cp += 8;
	}
	while (n-- > 0)
		*cp = TIFFBitRevTable[*cp], cp++;
}