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Unified Diff: xz/src/liblzma/delta/delta_encoder.c

Issue 2869016: Add an unpatched version of xz, XZ Utils, to /trunk/deps/third_party (Closed) Base URL: svn://svn.chromium.org/chrome/trunk/deps/third_party/
Patch Set: Created 10 years, 6 months ago
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Index: xz/src/liblzma/delta/delta_encoder.c
===================================================================
--- xz/src/liblzma/delta/delta_encoder.c (revision 0)
+++ xz/src/liblzma/delta/delta_encoder.c (revision 0)
@@ -0,0 +1,121 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file delta_encoder.c
+/// \brief Delta filter encoder
+//
+// Author: Lasse Collin
+//
+// This file has been put into the public domain.
+// You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "delta_encoder.h"
+#include "delta_private.h"
+
+
+/// Copies and encodes the data at the same time. This is used when Delta
+/// is the first filter in the chain (and thus the last filter in the
+/// encoder's filter stack).
+static void
+copy_and_encode(lzma_coder *coder,
+ const uint8_t *restrict in, uint8_t *restrict out, size_t size)
+{
+ const size_t distance = coder->distance;
+
+ for (size_t i = 0; i < size; ++i) {
+ const uint8_t tmp = coder->history[
+ (distance + coder->pos) & 0xFF];
+ coder->history[coder->pos-- & 0xFF] = in[i];
+ out[i] = in[i] - tmp;
+ }
+}
+
+
+/// Encodes the data in place. This is used when we are the last filter
+/// in the chain (and thus non-last filter in the encoder's filter stack).
+static void
+encode_in_place(lzma_coder *coder, uint8_t *buffer, size_t size)
+{
+ const size_t distance = coder->distance;
+
+ for (size_t i = 0; i < size; ++i) {
+ const uint8_t tmp = coder->history[
+ (distance + coder->pos) & 0xFF];
+ coder->history[coder->pos-- & 0xFF] = buffer[i];
+ buffer[i] -= tmp;
+ }
+}
+
+
+static lzma_ret
+delta_encode(lzma_coder *coder, lzma_allocator *allocator,
+ const uint8_t *restrict in, size_t *restrict in_pos,
+ size_t in_size, uint8_t *restrict out,
+ size_t *restrict out_pos, size_t out_size, lzma_action action)
+{
+ lzma_ret ret;
+
+ if (coder->next.code == NULL) {
+ const size_t in_avail = in_size - *in_pos;
+ const size_t out_avail = out_size - *out_pos;
+ const size_t size = my_min(in_avail, out_avail);
+
+ copy_and_encode(coder, in + *in_pos, out + *out_pos, size);
+
+ *in_pos += size;
+ *out_pos += size;
+
+ ret = action != LZMA_RUN && *in_pos == in_size
+ ? LZMA_STREAM_END : LZMA_OK;
+
+ } else {
+ const size_t out_start = *out_pos;
+
+ ret = coder->next.code(coder->next.coder, allocator,
+ in, in_pos, in_size, out, out_pos, out_size,
+ action);
+
+ encode_in_place(coder, out + out_start, *out_pos - out_start);
+ }
+
+ return ret;
+}
+
+
+static lzma_ret
+delta_encoder_update(lzma_coder *coder, lzma_allocator *allocator,
+ const lzma_filter *filters_null lzma_attribute((unused)),
+ const lzma_filter *reversed_filters)
+{
+ // Delta doesn't and will never support changing the options in
+ // the middle of encoding. If the app tries to change them, we
+ // simply ignore them.
+ return lzma_next_filter_update(
+ &coder->next, allocator, reversed_filters + 1);
+}
+
+
+extern lzma_ret
+lzma_delta_encoder_init(lzma_next_coder *next, lzma_allocator *allocator,
+ const lzma_filter_info *filters)
+{
+ next->code = &delta_encode;
+ next->update = &delta_encoder_update;
+ return lzma_delta_coder_init(next, allocator, filters);
+}
+
+
+extern lzma_ret
+lzma_delta_props_encode(const void *options, uint8_t *out)
+{
+ // The caller must have already validated the options, so it's
+ // LZMA_PROG_ERROR if they are invalid.
+ if (lzma_delta_coder_memusage(options) == UINT64_MAX)
+ return LZMA_PROG_ERROR;
+
+ const lzma_options_delta *opt = options;
+ out[0] = opt->dist - LZMA_DELTA_DIST_MIN;
+
+ return LZMA_OK;
+}
Property changes on: xz/src/liblzma/delta/delta_encoder.c
___________________________________________________________________
Added: svn:eol-style
+ LF
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