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authorLasse Collin <lasse.collin@tukaani.org>2007-12-09 00:42:33 +0200
committerLasse Collin <lasse.collin@tukaani.org>2007-12-09 00:42:33 +0200
commit5d018dc03549c1ee4958364712fb0c94e1bf2741 (patch)
tree1b211911fb33fddb3f04b77f99e81df23623ffc4 /src/liblzma/simple/x86.c
downloadxz-5d018dc03549c1ee4958364712fb0c94e1bf2741.tar.xz
Imported to git.
Diffstat (limited to 'src/liblzma/simple/x86.c')
-rw-r--r--src/liblzma/simple/x86.c161
1 files changed, 161 insertions, 0 deletions
diff --git a/src/liblzma/simple/x86.c b/src/liblzma/simple/x86.c
new file mode 100644
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--- /dev/null
+++ b/src/liblzma/simple/x86.c
@@ -0,0 +1,161 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file x86.c
+/// \brief Filter for x86 binaries (BCJ filter)
+//
+// Copyright (C) 1999-2006 Igor Pavlov
+// Copyright (C) 2007 Lasse Collin
+//
+// This library is free software; you can redistribute it and/or
+// modify it under the terms of the GNU Lesser General Public
+// License as published by the Free Software Foundation; either
+// version 2.1 of the License, or (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// Lesser General Public License for more details.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "simple_private.h"
+
+
+#define Test86MSByte(b) ((b) == 0 || (b) == 0xFF)
+
+
+struct lzma_simple_s {
+ uint32_t prev_mask;
+ uint32_t prev_pos;
+};
+
+
+static size_t
+x86_code(lzma_simple *simple, uint32_t now_pos, bool is_encoder,
+ uint8_t *buffer, size_t size)
+{
+ static const bool MASK_TO_ALLOWED_STATUS[8]
+ = { true, true, true, false, true, false, false, false };
+
+ static const uint32_t MASK_TO_BIT_NUMBER[8]
+ = { 0, 1, 2, 2, 3, 3, 3, 3 };
+
+ uint32_t prev_mask = simple->prev_mask;
+ uint32_t prev_pos = simple->prev_pos;
+
+ if (size < 5)
+ return 0;
+
+ if (now_pos - prev_pos > 5)
+ prev_pos = now_pos - 5;
+
+ const size_t limit = size - 5;
+ size_t buffer_pos = 0;
+
+ while (buffer_pos <= limit) {
+ uint8_t b = buffer[buffer_pos];
+ if (b != 0xE8 && b != 0xE9) {
+ ++buffer_pos;
+ continue;
+ }
+
+ const uint32_t offset = now_pos + (uint32_t)(buffer_pos)
+ - prev_pos;
+ prev_pos = now_pos + (uint32_t)(buffer_pos);
+
+ if (offset > 5) {
+ prev_mask = 0;
+ } else {
+ for (uint32_t i = 0; i < offset; ++i) {
+ prev_mask &= 0x77;
+ prev_mask <<= 1;
+ }
+ }
+
+ b = buffer[buffer_pos + 4];
+
+ if (Test86MSByte(b)
+ && MASK_TO_ALLOWED_STATUS[(prev_mask >> 1) & 0x7]
+ && (prev_mask >> 1) < 0x10) {
+
+ uint32_t src = ((uint32_t)(b) << 24)
+ | ((uint32_t)(buffer[buffer_pos + 3]) << 16)
+ | ((uint32_t)(buffer[buffer_pos + 2]) << 8)
+ | (buffer[buffer_pos + 1]);
+
+ uint32_t dest;
+ while (true) {
+ if (is_encoder)
+ dest = src + (now_pos + (uint32_t)(
+ buffer_pos) + 5);
+ else
+ dest = src - (now_pos + (uint32_t)(
+ buffer_pos) + 5);
+
+ if (prev_mask == 0)
+ break;
+
+ const uint32_t i = MASK_TO_BIT_NUMBER[
+ prev_mask >> 1];
+
+ b = (uint8_t)(dest >> (24 - i * 8));
+
+ if (!Test86MSByte(b))
+ break;
+
+ src = dest ^ ((1 << (32 - i * 8)) - 1);
+ }
+
+ buffer[buffer_pos + 4]
+ = (uint8_t)(~(((dest >> 24) & 1) - 1));
+ buffer[buffer_pos + 3] = (uint8_t)(dest >> 16);
+ buffer[buffer_pos + 2] = (uint8_t)(dest >> 8);
+ buffer[buffer_pos + 1] = (uint8_t)(dest);
+ buffer_pos += 5;
+ prev_mask = 0;
+
+ } else {
+ ++buffer_pos;
+ prev_mask |= 1;
+ if (Test86MSByte(b))
+ prev_mask |= 0x10;
+ }
+ }
+
+ simple->prev_mask = prev_mask;
+ simple->prev_pos = prev_pos;
+
+ return buffer_pos;
+}
+
+
+static lzma_ret
+x86_coder_init(lzma_next_coder *next, lzma_allocator *allocator,
+ const lzma_filter_info *filters, bool is_encoder)
+{
+ const lzma_ret ret = lzma_simple_coder_init(next, allocator, filters,
+ &x86_code, sizeof(lzma_simple), 5, is_encoder);
+
+ if (ret == LZMA_OK) {
+ next->coder->simple->prev_mask = 0;
+ next->coder->simple->prev_pos = (uint32_t)(-5);
+ }
+
+ return ret;
+}
+
+
+extern lzma_ret
+lzma_simple_x86_encoder_init(lzma_next_coder *next, lzma_allocator *allocator,
+ const lzma_filter_info *filters)
+{
+ return x86_coder_init(next, allocator, filters, true);
+}
+
+
+extern lzma_ret
+lzma_simple_x86_decoder_init(lzma_next_coder *next, lzma_allocator *allocator,
+ const lzma_filter_info *filters)
+{
+ return x86_coder_init(next, allocator, filters, false);
+}