New compression/decompression API

[wimlib] / include / wimlib / compress_common.h

diff --git a/include/wimlib/compress_common.h b/include/wimlib/compress_common.h
new file mode 100644 (file)
index 0000000..14b32f4
--- /dev/null
+++ b/include/wimlib/compress_common.h
@@ -0,0 +1,97 @@
+/*
+ * compress_common.h
+ *
+ * Header for compression code shared by multiple compression formats.
+ */
+
+#ifndef _WIMLIB_COMPRESS_COMMON_H
+#define _WIMLIB_COMPRESS_COMMON_H
+
+#include "wimlib/types.h"
+
+/* 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
+
+/* Structure to keep track of the current state sending bits and bytes to the
+ * compressed output buffer.  */
+struct output_bitstream {
+
+       /* Variable that holds up to 16 bits that haven't yet been flushed to
+        * the output.  */
+       u16 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;
+
+       /* 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;
+
+       /* Set to true if the buffer has been exhausted.  */
+       bool overrun;
+};
+
+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 max_lazy_match;
+       unsigned too_far;
+};
+
+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 */