wimlib.net Git - wimlib/blob - include/wimlib/compress.h

   1 /*
   2  * compress.h
   3  *
   4  * Header for compression code shared by multiple compression formats.
   5  */
   6
   7 #ifndef _WIMLIB_COMPRESS_H
   8 #define _WIMLIB_COMPRESS_H
   9
  10 #include "wimlib/endianness.h"
  11 #include "wimlib/types.h"
  12
  13 typedef u16 output_bitbuf_t;
  14
  15 /* Variable type that can represent all possible window positions.  */
  16 typedef u32 freq_t;
  17 #ifndef INPUT_IDX_T_DEFINED
  18 #define INPUT_IDX_T_DEFINED
  19 typedef u32 input_idx_t;
  20 #endif
  21
  22 /* Structure to keep track of the current position in the compressed output. */
  23 struct output_bitstream {
  24
  25         /* A variable to buffer writing bits to the output and is flushed to the
  26          * compressed output when full. */
  27         output_bitbuf_t bitbuf;
  28
  29         /* Number of free bits in @bitbuf */
  30         unsigned free_bits;
  31
  32         /* Pointer to the start of the output buffer.  */
  33         u8 *output_start;
  34
  35         /* Position at which to write the next 16 bits.  */
  36         u8 *bit_output;
  37
  38         /* Next position to write 16 bits, after they are written to bit_output.
  39          * This is after @next_bit_output and may be separated from @bit_output
  40          * by literal bytes.  */
  41         u8 *next_bit_output;
  42
  43         /* Next position to write literal bytes.  This is after @bit_output and
  44          * @next_bit_output, and may be separated from them by literal bytes.
  45          */
  46         u8 *output;
  47
  48         /* Bytes remaining in @output buffer.  */
  49         input_idx_t bytes_remaining;
  50
  51         /* Set to true if the buffer has been exhausted.  */
  52         bool overrun;
  53 };
  54
  55 extern void
  56 init_output_bitstream(struct output_bitstream *ostream,
  57                       void *data, unsigned num_bytes);
  58
  59 extern input_idx_t
  60 flush_output_bitstream(struct output_bitstream *ostream);
  61
  62 extern void
  63 bitstream_put_bits(struct output_bitstream *ostream,
  64                    u32 bits, unsigned num_bits);
  65
  66 extern void
  67 bitstream_put_byte(struct output_bitstream *ostream, u8 n);
  68
  69 struct lz_params {
  70         unsigned min_match;
  71         unsigned max_match;
  72         unsigned max_offset;
  73         unsigned nice_match;
  74         unsigned good_match;
  75         unsigned max_chain_len;
  76         unsigned max_lazy_match;
  77         unsigned too_far;
  78 };
  79
  80 typedef void (*lz_record_match_t)(unsigned len, unsigned offset, void *ctx);
  81 typedef void (*lz_record_literal_t)(u8 lit, void *ctx);
  82
  83 extern void
  84 lz_analyze_block(const u8 window[],
  85                  input_idx_t window_size,
  86                  lz_record_match_t record_match,
  87                  lz_record_literal_t record_literal,
  88                  void *record_ctx,
  89                  const struct lz_params *params,
  90                  input_idx_t prev_tab[]);
  91
  92 extern void
  93 make_canonical_huffman_code(unsigned num_syms,
  94                             unsigned max_codeword_len,
  95                             const freq_t freq_tab[restrict],
  96                             u8 lens[restrict],
  97                             u16 codewords[restrict]);
  98
  99 #endif /* _WIMLIB_COMPRESS_H */