1 files changed, 141 insertions, 0 deletions
diff --git a/src/liblzma/common/microlzma_encoder.c b/src/liblzma/common/microlzma_encoder.c
new file mode 100644
index 0000000..a787ca2
--- /dev/null
+++ b/src/liblzma/common/microlzma_encoder.c
@@ -0,0 +1,141 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       microlzma_encoder.c
+/// \brief      Encode into MicroLZMA format
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "lzma_encoder.h"
+
+
+typedef struct {
+	/// LZMA1 encoder
+	lzma_next_coder lzma;
+
+	/// LZMA properties byte (lc/lp/pb)
+	uint8_t props;
+} lzma_microlzma_coder;
+
+
+static lzma_ret
+microlzma_encode(void *coder_ptr, const 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_microlzma_coder *coder = coder_ptr;
+
+	// Remember *out_pos so that we can overwrite the first byte with
+	// the LZMA properties byte.
+	const size_t out_start = *out_pos;
+
+	// Remember *in_pos so that we can set it based on how many
+	// uncompressed bytes were actually encoded.
+	const size_t in_start = *in_pos;
+
+	// Set the output size limit based on the available output space.
+	// We know that the encoder supports set_out_limit() so
+	// LZMA_OPTIONS_ERROR isn't possible. LZMA_BUF_ERROR is possible
+	// but lzma_code() has an assertion to not allow it to be returned
+	// from here and I don't want to change that for now, so
+	// LZMA_BUF_ERROR becomes LZMA_PROG_ERROR.
+	uint64_t uncomp_size;
+	if (coder->lzma.set_out_limit(coder->lzma.coder,
+			&uncomp_size, out_size - *out_pos) != LZMA_OK)
+		return LZMA_PROG_ERROR;
+
+	// set_out_limit fails if this isn't true.
+	assert(out_size - *out_pos >= 6);
+
+	// Encode as much as possible.
+	const lzma_ret ret = coder->lzma.code(coder->lzma.coder, allocator,
+			in, in_pos, in_size, out, out_pos, out_size, action);
+
+	if (ret != LZMA_STREAM_END) {
+		if (ret == LZMA_OK) {
+			assert(0);
+			return LZMA_PROG_ERROR;
+		}
+
+		return ret;
+	}
+
+	// The first output byte is bitwise-negation of the properties byte.
+	// We know that there is space for this byte because set_out_limit
+	// and the actual encoding succeeded.
+	out[out_start] = (uint8_t)(~coder->props);
+
+	// The LZMA encoder likely read more input than it was able to encode.
+	// Set *in_pos based on uncomp_size.
+	assert(uncomp_size <= in_size - in_start);
+	*in_pos = in_start + (size_t)(uncomp_size);
+
+	return ret;
+}
+
+
+static void
+microlzma_encoder_end(void *coder_ptr, const lzma_allocator *allocator)
+{
+	lzma_microlzma_coder *coder = coder_ptr;
+	lzma_next_end(&coder->lzma, allocator);
+	lzma_free(coder, allocator);
+	return;
+}
+
+
+static lzma_ret
+microlzma_encoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
+		const lzma_options_lzma *options)
+{
+	lzma_next_coder_init(&microlzma_encoder_init, next, allocator);
+
+	lzma_microlzma_coder *coder = next->coder;
+
+	if (coder == NULL) {
+		coder = lzma_alloc(sizeof(lzma_microlzma_coder), allocator);
+		if (coder == NULL)
+			return LZMA_MEM_ERROR;
+
+		next->coder = coder;
+		next->code = &microlzma_encode;
+		next->end = &microlzma_encoder_end;
+
+		coder->lzma = LZMA_NEXT_CODER_INIT;
+	}
+
+	// Encode the properties byte. Bitwise-negation of it will be the
+	// first output byte.
+	if (lzma_lzma_lclppb_encode(options, &coder->props))
+		return LZMA_OPTIONS_ERROR;
+
+	// Initialize the LZMA encoder.
+	const lzma_filter_info filters[2] = {
+		{
+			.id = LZMA_FILTER_LZMA1,
+			.init = &lzma_lzma_encoder_init,
+			.options = (void *)(options),
+		}, {
+			.init = NULL,
+		}
+	};
+
+	return lzma_next_filter_init(&coder->lzma, allocator, filters);
+}
+
+
+extern LZMA_API(lzma_ret)
+lzma_microlzma_encoder(lzma_stream *strm, const lzma_options_lzma *options)
+{
+	lzma_next_strm_init(microlzma_encoder_init, strm, options);
+
+	strm->internal->supported_actions[LZMA_FINISH] = true;
+
+	return LZMA_OK;
+
+}