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Diffstat (limited to 'lib/zlib/inftrees.h')
-rw-r--r-- | lib/zlib/inftrees.h | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/lib/zlib/inftrees.h b/lib/zlib/inftrees.h new file mode 100644 index 0000000..a10712d --- /dev/null +++ b/lib/zlib/inftrees.h @@ -0,0 +1,62 @@ +/* inftrees.h -- header to use inftrees.c + * Copyright (C) 1995-2005, 2010 Mark Adler + * For conditions of distribution and use, see copyright notice in zlib.h + */ + +/* WARNING: this file should *not* be used by applications. It is + part of the implementation of the compression library and is + subject to change. Applications should only use zlib.h. + */ + +/* Structure for decoding tables. Each entry provides either the + information needed to do the operation requested by the code that + indexed that table entry, or it provides a pointer to another + table that indexes more bits of the code. op indicates whether + the entry is a pointer to another table, a literal, a length or + distance, an end-of-block, or an invalid code. For a table + pointer, the low four bits of op is the number of index bits of + that table. For a length or distance, the low four bits of op + is the number of extra bits to get after the code. bits is + the number of bits in this code or part of the code to drop off + of the bit buffer. val is the actual byte to output in the case + of a literal, the base length or distance, or the offset from + the current table to the next table. Each entry is four bytes. */ +typedef struct { + unsigned char op; /* operation, extra bits, table bits */ + unsigned char bits; /* bits in this part of the code */ + unsigned short val; /* offset in table or code value */ +} code; + +/* op values as set by inflate_table(): + 00000000 - literal + 0000tttt - table link, tttt != 0 is the number of table index bits + 0001eeee - length or distance, eeee is the number of extra bits + 01100000 - end of block + 01000000 - invalid code + */ + +/* Maximum size of the dynamic table. The maximum number of code structures is + 1444, which is the sum of 852 for literal/length codes and 592 for distance + codes. These values were found by exhaustive searches using the program + examples/enough.c found in the zlib distribution. The arguments to that + program are the number of symbols, the initial root table size, and the + maximum bit length of a code. "enough 286 9 15" for literal/length codes + returns returns 852, and "enough 30 6 15" for distance codes returns 592. + The initial root table size (9 or 6) is found in the fifth argument of the + inflate_table() calls in inflate.c and infback.c. If the root table size is + changed, then these maximum sizes would be need to be recalculated and + updated. */ +#define ENOUGH_LENS 852 +#define ENOUGH_DISTS 592 +#define ENOUGH (ENOUGH_LENS+ENOUGH_DISTS) + +/* Type of code to build for inflate_table() */ +typedef enum { + CODES, + LENS, + DISTS +} codetype; + +int ZLIB_INTERNAL inflate_table(codetype type, unsigned short FAR *lens, + unsigned codes, code FAR * FAR *table, + unsigned FAR *bits, unsigned short FAR *work); |