diff options
Diffstat (limited to 'cpan/Compress-Raw-Zlib/zlib-src/trees.c')
| -rw-r--r-- | cpan/Compress-Raw-Zlib/zlib-src/trees.c | 40 |
1 files changed, 30 insertions, 10 deletions
diff --git a/cpan/Compress-Raw-Zlib/zlib-src/trees.c b/cpan/Compress-Raw-Zlib/zlib-src/trees.c index de0b7f210c..d9c807d561 100644 --- a/cpan/Compress-Raw-Zlib/zlib-src/trees.c +++ b/cpan/Compress-Raw-Zlib/zlib-src/trees.c @@ -1,5 +1,5 @@ /* trees.c -- output deflated data using Huffman coding - * Copyright (C) 1995-2012 Jean-loup Gailly + * Copyright (C) 1995-2010 Jean-loup Gailly * detect_data_type() function provided freely by Cosmin Truta, 2006 * For conditions of distribution and use, see copyright notice in zlib.h */ @@ -74,6 +74,11 @@ local const uch bl_order[BL_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. */ @@ -394,6 +399,7 @@ void ZLIB_INTERNAL _tr_init( s->bi_buf = 0; s->bi_valid = 0; + s->last_eob_len = 8; /* enough lookahead for inflate */ #ifdef DEBUG s->compressed_len = 0L; s->bits_sent = 0L; @@ -879,17 +885,15 @@ void ZLIB_INTERNAL _tr_stored_block( } /* =========================================================================== - * Flush the bits in the bit buffer to pending output (leaves at most 7 bits) - */ -void ZLIB_INTERNAL _tr_flush_bits( - deflate_state *s) -{ - bi_flush(s); -} - -/* =========================================================================== * Send one empty static block to give enough lookahead for inflate. * This takes 10 bits, of which 7 may remain in the bit buffer. + * The current inflate code requires 9 bits of lookahead. If the + * last two codes for the previous block (real code plus EOB) were coded + * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode + * the last real code. In this case we send two empty static blocks instead + * of one. (There are no problems if the previous block is stored or fixed.) + * To simplify the code, we assume the worst case of last real code encoded + * on one bit only. */ void ZLIB_INTERNAL _tr_align( deflate_state *s) @@ -900,6 +904,20 @@ void ZLIB_INTERNAL _tr_align( s->compressed_len += 10L; /* 3 for block type, 7 for EOB */ #endif bi_flush(s); + /* Of the 10 bits for the empty block, we have already sent + * (10 - bi_valid) bits. The lookahead for the last real code (before + * the EOB of the previous block) was thus at least one plus the length + * of the EOB plus what we have just sent of the empty static block. + */ + if (1 + s->last_eob_len + 10 - s->bi_valid < 9) { + send_bits(s, STATIC_TREES<<1, 3); + send_code(s, END_BLOCK, static_ltree); +#ifdef DEBUG + s->compressed_len += 10L; +#endif + bi_flush(s); + } + s->last_eob_len = 7; } /* =========================================================================== @@ -1102,6 +1120,7 @@ local void compress_block( } while (lx < s->last_lit); send_code(s, END_BLOCK, ltree); + s->last_eob_len = ltree[END_BLOCK].Len; } /* =========================================================================== @@ -1209,6 +1228,7 @@ local void copy_block( int header) { bi_windup(s); /* align on byte boundary */ + s->last_eob_len = 8; /* enough lookahead for inflate */ if (header) { put_short(s, (ush)len); |