/*
* compress.h
*
- * Functions useful for compression, mainly bitstreams.
+ * Header for compression code shared by multiple compression formats.
*/
#ifndef _WIMLIB_COMPRESS_H
#define _WIMLIB_COMPRESS_H
-#include "wimlib/endianness.h"
#include "wimlib/types.h"
-typedef u16 output_bitbuf_t;
+/* Variable type that can represent all possible window positions. */
+#ifndef INPUT_IDX_T_DEFINED
+#define INPUT_IDX_T_DEFINED
+typedef u32 input_idx_t;
+#endif
-/* Assuming that WIM chunks are at most 32768 bytes, 16 bits is enough for any
- * symbol frequency. */
-typedef u16 freq_t;
-
-/* Structure to keep track of the current position in the compressed output. */
+/* Structure to keep track of the current state sending bits and bytes to the
+ * compressed output buffer. */
struct output_bitstream {
- /* A variable to buffer writing bits to the output and is flushed to the
- * compressed output when full. */
- output_bitbuf_t bitbuf;
+ /* Variable that holds up to 16 bits that haven't yet been flushed to
+ * the output. */
+ u16 bitbuf;
- /* Number of free bits in @bitbuf */
+ /* Number of free bits in @bitbuf; that is, 16 minus the number of valid
+ * bits in @bitbuf. */
unsigned free_bits;
+ /* Pointer to the start of the output buffer. */
+ u8 *output_start;
+
+ /* Position at which to write the next 16 bits. */
u8 *bit_output;
+
+ /* Next position to write 16 bits, after they are written to bit_output.
+ * This is after @next_bit_output and may be separated from @bit_output
+ * by literal bytes. */
u8 *next_bit_output;
- /* Pointer to the next byte in the compressed output. */
+ /* Next position to write literal bytes. This is after @bit_output and
+ * @next_bit_output, and may be separated from them by literal bytes.
+ */
u8 *output;
+ /* Number of bytes remaining in the @output buffer. */
+ input_idx_t bytes_remaining;
- /* Number of bytes left in the memory pointed to by @output. */
- int num_bytes_remaining;
+ /* Set to true if the buffer has been exhausted. */
+ bool overrun;
};
-static inline int bitstream_put_byte(struct output_bitstream *ostream,
- u8 n)
-{
- if (ostream->num_bytes_remaining < 1)
- return 1;
- *ostream->output = n;
- ostream->output++;
- ostream->num_bytes_remaining--;
- return 0;
-}
-
-static inline int bitstream_put_two_bytes(struct output_bitstream *ostream,
- u16 n)
-{
- if (ostream->num_bytes_remaining < 2)
- return 1;
- *(u16*)ostream->output = cpu_to_le16(n);
- ostream->output += 2;
- ostream->num_bytes_remaining -= 2;
- return 0;
-}
+extern void
+init_output_bitstream(struct output_bitstream *ostream,
+ void *data, unsigned num_bytes);
+
+extern input_idx_t
+flush_output_bitstream(struct output_bitstream *ostream);
+
+extern void
+bitstream_put_bits(struct output_bitstream *ostream,
+ u32 bits, unsigned num_bits);
+
+extern void
+bitstream_put_byte(struct output_bitstream *ostream, u8 n);
struct lz_params {
unsigned min_match;
unsigned max_match;
+ unsigned max_offset;
unsigned nice_match;
unsigned good_match;
unsigned max_chain_len;
unsigned too_far;
};
-typedef unsigned (*lz_record_match_t)(unsigned, unsigned, void *, void *);
-typedef unsigned (*lz_record_literal_t)(u8, void *);
-
-extern unsigned lz_analyze_block(const u8 uncompressed_data[],
- unsigned uncompressed_len,
- u32 match_tab[],
- lz_record_match_t record_match,
- lz_record_literal_t record_literal,
- void *record_match_arg1,
- void *record_match_arg2,
- void *record_literal_arg,
- const struct lz_params *params);
-
-extern int bitstream_put_bits(struct output_bitstream *ostream,
- output_bitbuf_t bits, unsigned num_bits);
-
-extern void init_output_bitstream(struct output_bitstream *ostream,
- void *data, unsigned num_bytes);
-
-extern int flush_output_bitstream(struct output_bitstream *ostream);
-
-extern void make_canonical_huffman_code(unsigned num_syms,
- unsigned max_codeword_len,
- const freq_t freq_tab[],
- u8 lens[],
- u16 codewords[]);
+typedef void (*lz_record_match_t)(unsigned len, unsigned offset, void *ctx);
+typedef void (*lz_record_literal_t)(u8 lit, void *ctx);
+
+extern void
+lz_analyze_block(const u8 window[restrict],
+ input_idx_t window_size,
+ lz_record_match_t record_match,
+ lz_record_literal_t record_literal,
+ void *record_ctx,
+ const struct lz_params *params,
+ input_idx_t prev_tab[restrict]);
+
+extern void
+make_canonical_huffman_code(unsigned num_syms,
+ unsigned max_codeword_len,
+ const input_idx_t freq_tab[restrict],
+ u8 lens[restrict],
+ u16 codewords[restrict]);
#endif /* _WIMLIB_COMPRESS_H */