/* inftrees.h -- header to use inftrees.c
- * Copyright (C) 1995 Mark Adler
- * For conditions of distribution and use, see copyright notice in zlib.h
+ * 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
subject to change. Applications should only use zlib.h.
*/
-/* Huffman code lookup table entry--this entry is four bytes for machines
- that have 16-bit pointers (e.g. PC's in the small or medium model). */
-
-typedef struct inflate_huft_s FAR inflate_huft;
-
-struct inflate_huft_s {
- union {
- struct {
- Byte Exop; /* number of extra bits or operation */
- Byte Bits; /* number of bits in this code or subcode */
- } what;
- Bytef *pad; /* pad structure to a power of 2 (4 bytes for */
- } word; /* 16-bit, 8 bytes for 32-bit machines) */
- union {
- uInt Base; /* literal, length base, or distance base */
- inflate_huft *Next; /* pointer to next level of table */
- } more;
-};
-
-#ifdef DEBUG
- extern uInt inflate_hufts;
-#endif
-
-extern int inflate_trees_bits OF((
- uIntf *, /* 19 code lengths */
- uIntf *, /* bits tree desired/actual depth */
- inflate_huft * FAR *, /* bits tree result */
- z_stream *)); /* for zalloc, zfree functions */
-
-extern int inflate_trees_dynamic OF((
- uInt, /* number of literal/length codes */
- uInt, /* number of distance codes */
- uIntf *, /* that many (total) code lengths */
- uIntf *, /* literal desired/actual bit depth */
- uIntf *, /* distance desired/actual bit depth */
- inflate_huft * FAR *, /* literal/length tree result */
- inflate_huft * FAR *, /* distance tree result */
- z_stream *)); /* for zalloc, zfree functions */
-
-extern int inflate_trees_fixed OF((
- uIntf *, /* literal desired/actual bit depth */
- uIntf *, /* distance desired/actual bit depth */
- inflate_huft * FAR *, /* literal/length tree result */
- inflate_huft * FAR *)); /* distance tree result */
-
-extern int inflate_trees_free OF((
- inflate_huft *, /* tables to free */
- z_stream *)); /* for zfree function */
+/* 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 distribtution. 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 OF((codetype type, unsigned short FAR *lens,
+ unsigned codes, code FAR * FAR *table,
+ unsigned FAR *bits, unsigned short FAR *work));
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