libkern/zlib/inflate.c

7  * as defined in and that are subject to the Apple Public Source License
8  * Version 2.0 (the 'License'). You may not use this file except in
30  * For conditions of distribution and use, see copyright notice in zlib.h
43  * - Use pointers for available input and output checking in inffast.c
44  * - Remove input and output counters in inffast.c
46  * - Remove unnecessary second byte pull from length extra in inffast.c
47  * - Unroll direct copy to three copies per loop in inffast.c
51  * - Correct filename to inffixed.h for fixed tables in inflate.c
52  * - Make hbuf[] unsigned char to match parameter type in inflate.c
54  *   to avoid negation problem on Alphas (64 bit) in inflate.c
57  * - Add comments on state->bits assertion in inffast.c
58  * - Add comments on op field in inftrees.h
59  * - Fix bug in reuse of allocated window after inflateReset()
61  * - Remove distance extra == 0 check in inflate_fast()--only helps for lengths
62  * - Change post-increments to pre-increments in inflate_fast(), PPC biased?
64  * - Make MATCH copy in inflate() much faster for when inflate_fast() not used
66  *   buffer and bit count in inflate()--for speed when inflate_fast() not used
69  * - Split ptr - 257 statements in inflate_table() to avoid compiler warnings
71  * - Add comments in inffast.c to introduce the inflate_fast() routine
72  * - Rearrange window copies in inflate_fast() for speed and simplification
73  * - Unroll last copy for window match in inflate_fast()
74  * - Use local copies of window variables in inflate_fast() for speed
75  * - Pull out common write == 0 case for speed in inflate_fast()
76  * - Make op and len in inflate_fast() unsigned for consistency
77  * - Add FAR to lcode and dcode declarations in inflate_fast()
78  * - Simplified bad distance check in inflate_fast()
79  * - Added inflateBackInit(), inflateBack(), and inflateBackEnd() in new
86  *   input in strm.
87  * - Fixed stored blocks bug in inflateBack()
90  * - Added comments in inffast.c on effectiveness of POSTINC
94  * - Changed type of window in inflateBackInit() to unsigned char *
102  *   for the in() and out() functions
107  * The history for versions after 1.2.0 are in ChangeLog in zlib distribution.
183     strm->msg = Z_NULL;                 /* in case we return an error */
229    thereafter.  This reduces the size of the code by about 2K bytes, in
341    when a window is already in use, or when output has been written during this
349    output will fall in the output data, making match copies simpler and faster.
369     /* if window not in use yet, initialize */
431 /* Load registers with state in inflate() for speed */
442 /* Restore state from registers in inflate() */
470 /* Assure that there are at least n bits in the bit accumulator.  If there is
496 /* Reverse the bytes in a 32-bit value */
530    gives the low n bits in the accumulator.  When done, DROPBITS(n) drops
534    and a NEEDBITS(8), then BITS(8) would return the next byte in the stream.
538    PULLBYTE() directly in order to pull just enough bytes to decode the next
543    if NEEDBITS() returns in the loop.  For example, want, need, and keep
544    would all have to actually be part of the saved state in case NEEDBITS()
565    during that inflate() call in order to return the proper return code.
566    Progress is defined as a change in either strm->avail_in or strm->avail_out.
568    output written.  If a goto inf_leave occurs in the middle of decompression
575    documented in zlib.h of Z_SYNC_FLUSH.  Furthermore, inflate() always defers
577    provides the effect documented in zlib.h for Z_FINISH when the entire input
592     unsigned bits;              /* bits in bit buffer */
593     unsigned in, out;           /* save starting available input and output */
613     in = have;
954             /* handle error breaks in while */
1169     in -= strm->avail_in;
1171     strm->total_in += in;
1179     if (((in == 0 && out == 0) || flush == Z_FINISH) && ret == Z_OK)
1260    found in order so far, in 0..3.  On return *have is updated to the new
1295     unsigned long in, out;      /* temporary to save total_in and total_out */
1304     /* if first time, start search in bit buffer */
1327     in = strm->total_in;  out = strm->total_out;
1329     strm->total_in = in;  strm->total_out = out;