Externals: Add libLZMA.

Externals/liblzma/simple/simple_encoder.c

@@ -0,0 +1,38 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       simple_encoder.c
+/// \brief      Properties encoder for simple filters
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "simple_encoder.h"
+
+
+extern lzma_ret
+lzma_simple_props_size(uint32_t *size, const void *options)
+{
+	const lzma_options_bcj *const opt = options;
+	*size = (opt == NULL || opt->start_offset == 0) ? 0 : 4;
+	return LZMA_OK;
+}
+
+
+extern lzma_ret
+lzma_simple_props_encode(const void *options, uint8_t *out)
+{
+	const lzma_options_bcj *const opt = options;
+
+	// The default start offset is zero, so we don't need to store any
+	// options unless the start offset is non-zero.
+	if (opt == NULL || opt->start_offset == 0)
+		return LZMA_OK;
+
+	unaligned_write32le(out, opt->start_offset);
+
+	return LZMA_OK;
+}