X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=lzma%2Flz%2Flz_decoder.h;fp=lzma%2Flz%2Flz_decoder.h;h=277900afb71454f0daa597ea6994a0e39f27f341;hb=32b8a6b26ed8843828e03e505d2256960bda0980;hp=0000000000000000000000000000000000000000;hpb=d48fc23a4bcf8ca3c406d6e8c8a6f8c6b0fa2f1e;p=zpackage

diff --git a/lzma/lz/lz_decoder.h b/lzma/lz/lz_decoder.h
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+++ b/lzma/lz/lz_decoder.h
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+///////////////////////////////////////////////////////////////////////////////
+//
+/// \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