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Allow deflatePrime() to insert bits in the middle of a stream.

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This allows the insertion of multiple empty static blocks for the
purpose of efficiently bringing a stream to a byte boundary.
This commit is contained in:
Mark Adler 2012-01-07 09:54:40 -08:00
parent 19761b8506
commit 263b1a05b0
4 changed files with 26 additions and 13 deletions
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22
deflate.c
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@ -1,5 +1,5 @@
/* deflate.c -- compress data using the deflation algorithm /* deflate.c -- compress data using the deflation algorithm
* Copyright (C) 1995-2011 Jean-loup Gailly and Mark Adler * Copyright (C) 1995-2012 Jean-loup Gailly and Mark Adler
* For conditions of distribution and use, see copyright notice in zlib.h * For conditions of distribution and use, see copyright notice in zlib.h
*/ */
@ -52,7 +52,7 @@
#include "deflate.h" #include "deflate.h"
const char deflate_copyright[] = const char deflate_copyright[] =
" deflate 1.2.5.3 Copyright 1995-2011 Jean-loup Gailly and Mark Adler "; " deflate 1.2.5.3 Copyright 1995-2012 Jean-loup Gailly and Mark Adler ";
/* /*
If you use the zlib library in a product, an acknowledgment is welcome If you use the zlib library in a product, an acknowledgment is welcome
in the documentation of your product. If for some reason you cannot in the documentation of your product. If for some reason you cannot
@ -464,9 +464,23 @@ int ZEXPORT deflatePrime (strm, bits, value)
int bits; int bits;
int value; int value;
{ {
deflate_state *s;
int put;
if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
strm->state->bi_valid = bits; s = strm->state;
strm->state->bi_buf = (ush)(value & ((1 << bits) - 1)); if ((Bytef *)(s->d_buf) < s->pending_out + ((Buf_size + 7) >> 3))
return Z_BUF_ERROR;
do {
put = Buf_size - s->bi_valid;
if (put > bits)
put = bits;
s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid);
s->bi_valid += put;
_tr_flush_bits(s);
value >>= put;
bits -= put;
} while (bits);
return Z_OK; return Z_OK;
} }

5
deflate.h
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@ -1,5 +1,5 @@
/* deflate.h -- internal compression state /* deflate.h -- internal compression state
* Copyright (C) 1995-2010 Jean-loup Gailly * Copyright (C) 1995-2012 Jean-loup Gailly
* For conditions of distribution and use, see copyright notice in zlib.h * For conditions of distribution and use, see copyright notice in zlib.h
*/ */
@ -48,6 +48,9 @@
#define MAX_BITS 15 #define MAX_BITS 15
/* All codes must not exceed MAX_BITS bits */ /* All codes must not exceed MAX_BITS bits */
#define Buf_size 16
/* size of bit buffer in bi_buf */
#define INIT_STATE 42 #define INIT_STATE 42
#define EXTRA_STATE 69 #define EXTRA_STATE 69
#define NAME_STATE 73 #define NAME_STATE 73

7
trees.c
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@ -1,5 +1,5 @@
/* trees.c -- output deflated data using Huffman coding /* trees.c -- output deflated data using Huffman coding
* Copyright (C) 1995-2010 Jean-loup Gailly * Copyright (C) 1995-2012 Jean-loup Gailly
* detect_data_type() function provided freely by Cosmin Truta, 2006 * detect_data_type() function provided freely by Cosmin Truta, 2006
* For conditions of distribution and use, see copyright notice in zlib.h * For conditions of distribution and use, see copyright notice in zlib.h
*/ */
@ -74,11 +74,6 @@ local const uch bl_order[BL_CODES]
* probability, to avoid transmitting the lengths for unused bit length codes. * probability, to avoid transmitting the lengths for unused bit length codes.
*/ */
#define Buf_size (8 * 2*sizeof(char))
/* Number of bits used within bi_buf. (bi_buf might be implemented on
* more than 16 bits on some systems.)
*/
/* =========================================================================== /* ===========================================================================
* Local data. These are initialized only once. * Local data. These are initialized only once.
*/ */

5
zlib.h
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@ -734,8 +734,9 @@ ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
than or equal to 16, and that many of the least significant bits of value than or equal to 16, and that many of the least significant bits of value
will be inserted in the output. will be inserted in the output.
deflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source deflatePrime returns Z_OK if success, Z_BUF_ERROR if there was not enough
stream state was inconsistent. room in the internal buffer to insert the bits, or Z_STREAM_ERROR if the
source stream state was inconsistent.
*/ */
ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm, ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,