1 files changed, 73 insertions, 0 deletions
diff --git a/src/liblzma/delta/delta_common.c b/src/liblzma/delta/delta_common.c
new file mode 100644
index 0000000..4768201
--- /dev/null
+++ b/src/liblzma/delta/delta_common.c
@@ -0,0 +1,73 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       delta_common.c
+/// \brief      Common stuff for Delta encoder and decoder
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "delta_common.h"
+#include "delta_private.h"
+
+
+static void
+delta_coder_end(void *coder_ptr, const lzma_allocator *allocator)
+{
+	lzma_delta_coder *coder = coder_ptr;
+	lzma_next_end(&coder->next, allocator);
+	lzma_free(coder, allocator);
+	return;
+}
+
+
+extern lzma_ret
+lzma_delta_coder_init(lzma_next_coder *next, const lzma_allocator *allocator,
+		const lzma_filter_info *filters)
+{
+	// Allocate memory for the decoder if needed.
+	lzma_delta_coder *coder = next->coder;
+	if (coder == NULL) {
+		coder = lzma_alloc(sizeof(lzma_delta_coder), allocator);
+		if (coder == NULL)
+			return LZMA_MEM_ERROR;
+
+		next->coder = coder;
+
+		// End function is the same for encoder and decoder.
+		next->end = &delta_coder_end;
+		coder->next = LZMA_NEXT_CODER_INIT;
+	}
+
+	// Validate the options.
+	if (lzma_delta_coder_memusage(filters[0].options) == UINT64_MAX)
+		return LZMA_OPTIONS_ERROR;
+
+	// Set the delta distance.
+	const lzma_options_delta *opt = filters[0].options;
+	coder->distance = opt->dist;
+
+	// Initialize the rest of the variables.
+	coder->pos = 0;
+	memzero(coder->history, LZMA_DELTA_DIST_MAX);
+
+	// Initialize the next decoder in the chain, if any.
+	return lzma_next_filter_init(&coder->next, allocator, filters + 1);
+}
+
+
+extern uint64_t
+lzma_delta_coder_memusage(const void *options)
+{
+	const lzma_options_delta *opt = options;
+
+	if (opt == NULL || opt->type != LZMA_DELTA_TYPE_BYTE
+			|| opt->dist < LZMA_DELTA_DIST_MIN
+			|| opt->dist > LZMA_DELTA_DIST_MAX)
+		return UINT64_MAX;
+
+	return sizeof(lzma_delta_coder);
+}