wimlib.net Git - wimlib/blob - src/comp.h

   1 /*
   2  * comp.h
   3  *
   4  * Functions useful for compression, mainly bitstreams.
   5  */
   6
   7 #ifndef _WIMLIB_COMP_H
   8 #define _WIMLIB_COMP_H
   9
  10 #include "util.h"
  11 #include "endianness.h"
  12
  13 typedef u16 output_bitbuf_t;
  14
  15 /* Structure to keep track of the current position in the compressed output. */
  16 struct output_bitstream {
  17
  18         /* A variable to buffer writing bits to the output and is flushed to the
  19          * compressed output when full. */
  20         output_bitbuf_t bitbuf;
  21
  22         /* Number of free bits in @bitbuf */
  23         uint free_bits;
  24
  25         u8 *bit_output;
  26         u8 *next_bit_output;
  27
  28         /* Pointer to the next byte in the compressed output. */
  29         u8 *output;
  30
  31
  32         /* Number of bytes left in the memory pointed to by @output. */
  33         int num_bytes_remaining;
  34 };
  35
  36 static inline int bitstream_put_byte(struct output_bitstream *ostream,
  37                                      u8 n)
  38 {
  39         if (ostream->num_bytes_remaining < 1)
  40                 return 1;
  41         *ostream->output = n;
  42         ostream->output++;
  43         ostream->num_bytes_remaining--;
  44         return 0;
  45 }
  46
  47 static inline int bitstream_put_two_bytes(struct output_bitstream *ostream,
  48                                           u16 n)
  49 {
  50         if (ostream->num_bytes_remaining < 2)
  51                 return 1;
  52         *(u16*)ostream->output = cpu_to_le16(n);
  53         ostream->output += 2;
  54         ostream->num_bytes_remaining -= 2;
  55         return 0;
  56 }
  57
  58 struct lz_params {
  59         uint min_match;
  60         uint max_match;
  61         uint nice_match;
  62         uint good_match;
  63         uint max_chain_len;
  64         uint max_lazy_match;
  65         uint too_far;
  66 };
  67
  68 typedef uint (*lz_record_match_t)(uint, uint, void *, void *);
  69 typedef uint (*lz_record_literal_t)(u8, void *);
  70
  71 extern uint lz_analyze_block(const u8 uncompressed_data[],
  72                              uint uncompressed_len,
  73                              u32 match_tab[],
  74                              lz_record_match_t record_match,
  75                              lz_record_literal_t record_literal,
  76                              void *record_match_arg1,
  77                              void *record_match_arg2,
  78                              void *record_literal_arg,
  79                              const struct lz_params *params);
  80
  81 extern int bitstream_put_bits(struct output_bitstream *ostream,
  82                               output_bitbuf_t bits, unsigned num_bits);
  83
  84 extern void init_output_bitstream(struct output_bitstream *ostream,
  85                                   void *data, unsigned num_bytes);
  86
  87 extern int flush_output_bitstream(struct output_bitstream *ostream);
  88
  89 extern void make_canonical_huffman_code(uint num_syms, uint max_codeword_len,
  90                                         const u32 freq_tab[], u8 lens[],
  91                                         u16 codewords[]);
  92
  93 #endif /* _WIMLIB_COMP_H */