--- /dev/null
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file lz_decoder.h
+/// \brief LZ out window
+///
+// Authors: Igor Pavlov
+// Lasse Collin
+//
+// This file has been put into the public domain.
+// You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef LZMA_LZ_DECODER_H
+#define LZMA_LZ_DECODER_H
+
+#include "common.h"
+
+
+typedef struct {
+ /// Pointer to the dictionary buffer. It can be an allocated buffer
+ /// internal to liblzma, or it can a be a buffer given by the
+ /// application when in single-call mode (not implemented yet).
+ uint8_t *buf;
+
+ /// Write position in dictionary. The next byte will be written to
+ /// buf[pos].
+ size_t pos;
+
+ /// Indicates how full the dictionary is. This is used by
+ /// dict_is_distance_valid() to detect corrupt files that would
+ /// read beyond the beginning of the dictionary.
+ size_t full;
+
+ /// Write limit
+ size_t limit;
+
+ /// Size of the dictionary
+ size_t size;
+
+ /// True when dictionary should be reset before decoding more data.
+ bool need_reset;
+
+} lzma_dict;
+
+
+typedef struct {
+ size_t dict_size;
+ const uint8_t *preset_dict;
+ size_t preset_dict_size;
+} lzma_lz_options;
+
+
+typedef struct {
+ /// Data specific to the LZ-based decoder
+ lzma_coder *coder;
+
+ /// Function to decode from in[] to *dict
+ lzma_ret (*code)(lzma_coder *restrict coder,
+ lzma_dict *restrict dict, const uint8_t *restrict in,
+ size_t *restrict in_pos, size_t in_size);
+
+ void (*reset)(lzma_coder *coder, const void *options);
+
+ /// Set the uncompressed size
+ void (*set_uncompressed)(lzma_coder *coder,
+ lzma_vli uncompressed_size);
+
+ /// Free allocated resources
+ void (*end)(lzma_coder *coder, const lzma_allocator *allocator);
+
+} lzma_lz_decoder;
+
+
+#define LZMA_LZ_DECODER_INIT \
+ (lzma_lz_decoder){ \
+ .coder = NULL, \
+ .code = NULL, \
+ .reset = NULL, \
+ .set_uncompressed = NULL, \
+ .end = NULL, \
+ }
+
+
+extern lzma_ret lzma_lz_decoder_init(lzma_next_coder *next,
+ const lzma_allocator *allocator,
+ const lzma_filter_info *filters,
+ lzma_ret (*lz_init)(lzma_lz_decoder *lz,
+ const lzma_allocator *allocator, const void *options,
+ lzma_lz_options *lz_options));
+
+extern uint64_t lzma_lz_decoder_memusage(size_t dictionary_size);
+
+extern void lzma_lz_decoder_uncompressed(
+ lzma_coder *coder, lzma_vli uncompressed_size);
+
+
+//////////////////////
+// Inline functions //
+//////////////////////
+
+/// Get a byte from the history buffer.
+static inline uint8_t
+dict_get(const lzma_dict *const dict, const uint32_t distance)
+{
+ return dict->buf[dict->pos - distance - 1
+ + (distance < dict->pos ? 0 : dict->size)];
+}
+
+
+/// Test if dictionary is empty.
+static inline bool
+dict_is_empty(const lzma_dict *const dict)
+{
+ return dict->full == 0;
+}
+
+
+/// Validate the match distance
+static inline bool
+dict_is_distance_valid(const lzma_dict *const dict, const size_t distance)
+{
+ return dict->full > distance;
+}
+
+
+/// Repeat *len bytes at distance.
+static inline bool
+dict_repeat(lzma_dict *dict, uint32_t distance, uint32_t *len)
+{
+ // Don't write past the end of the dictionary.
+ const size_t dict_avail = dict->limit - dict->pos;
+ uint32_t left = my_min(dict_avail, *len);
+ *len -= left;
+
+ // Repeat a block of data from the history. Because memcpy() is faster
+ // than copying byte by byte in a loop, the copying process gets split
+ // into three cases.
+ if (distance < left) {
+ // Source and target areas overlap, thus we can't use
+ // memcpy() nor even memmove() safely.
+ do {
+ dict->buf[dict->pos] = dict_get(dict, distance);
+ ++dict->pos;
+ } while (--left > 0);
+
+ } else if (distance < dict->pos) {
+ // The easiest and fastest case
+ memcpy(dict->buf + dict->pos,
+ dict->buf + dict->pos - distance - 1,
+ left);
+ dict->pos += left;
+
+ } else {
+ // The bigger the dictionary, the more rare this
+ // case occurs. We need to "wrap" the dict, thus
+ // we might need two memcpy() to copy all the data.
+ assert(dict->full == dict->size);
+ const uint32_t copy_pos
+ = dict->pos - distance - 1 + dict->size;
+ uint32_t copy_size = dict->size - copy_pos;
+
+ if (copy_size < left) {
+ memmove(dict->buf + dict->pos, dict->buf + copy_pos,
+ copy_size);
+ dict->pos += copy_size;
+ copy_size = left - copy_size;
+ memcpy(dict->buf + dict->pos, dict->buf, copy_size);
+ dict->pos += copy_size;
+ } else {
+ memmove(dict->buf + dict->pos, dict->buf + copy_pos,
+ left);
+ dict->pos += left;
+ }
+ }
+
+ // Update how full the dictionary is.
+ if (dict->full < dict->pos)
+ dict->full = dict->pos;
+
+ return unlikely(*len != 0);
+}
+
+
+/// Puts one byte into the dictionary. Returns true if the dictionary was
+/// already full and the byte couldn't be added.
+static inline bool
+dict_put(lzma_dict *dict, uint8_t byte)
+{
+ if (unlikely(dict->pos == dict->limit))
+ return true;
+
+ dict->buf[dict->pos++] = byte;
+
+ if (dict->pos > dict->full)
+ dict->full = dict->pos;
+
+ return false;
+}
+
+
+/// Copies arbitrary amount of data into the dictionary.
+static inline void
+dict_write(lzma_dict *restrict dict, const uint8_t *restrict in,
+ size_t *restrict in_pos, size_t in_size,
+ size_t *restrict left)
+{
+ // NOTE: If we are being given more data than the size of the
+ // dictionary, it could be possible to optimize the LZ decoder
+ // so that not everything needs to go through the dictionary.
+ // This shouldn't be very common thing in practice though, and
+ // the slowdown of one extra memcpy() isn't bad compared to how
+ // much time it would have taken if the data were compressed.
+
+ if (in_size - *in_pos > *left)
+ in_size = *in_pos + *left;
+
+ *left -= lzma_bufcpy(in, in_pos, in_size,
+ dict->buf, &dict->pos, dict->limit);
+
+ if (dict->pos > dict->full)
+ dict->full = dict->pos;
+
+ return;
+}
+
+
+static inline void
+dict_reset(lzma_dict *dict)
+{
+ dict->need_reset = true;
+ return;
+}
+
+#endif
projects / zpackage / blobdiff