X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=lzma%2Fcommon%2Fvli_encoder.c;fp=lzma%2Fcommon%2Fvli_encoder.c;h=f8642694e291095538a68135f55667f105e312b4;hb=32b8a6b26ed8843828e03e505d2256960bda0980;hp=0000000000000000000000000000000000000000;hpb=d48fc23a4bcf8ca3c406d6e8c8a6f8c6b0fa2f1e;p=zpackage

diff --git a/lzma/common/vli_encoder.c b/lzma/common/vli_encoder.c
new file mode 100644
index 0000000..f864269
--- /dev/null
+++ b/lzma/common/vli_encoder.c
@@ -0,0 +1,69 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       vli_encoder.c
+/// \brief      Encodes variable-length integers
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "common.h"
+
+
+extern LZMA_API(lzma_ret)
+lzma_vli_encode(lzma_vli vli, size_t *vli_pos,
+		uint8_t *restrict out, size_t *restrict out_pos,
+		size_t out_size)
+{
+	// If we haven't been given vli_pos, work in single-call mode.
+	size_t vli_pos_internal = 0;
+	if (vli_pos == NULL) {
+		vli_pos = &vli_pos_internal;
+
+		// In single-call mode, we expect that the caller has
+		// reserved enough output space.
+		if (*out_pos >= out_size)
+			return LZMA_PROG_ERROR;
+	} else {
+		// This never happens when we are called by liblzma, but
+		// may happen if called directly from an application.
+		if (*out_pos >= out_size)
+			return LZMA_BUF_ERROR;
+	}
+
+	// Validate the arguments.
+	if (*vli_pos >= LZMA_VLI_BYTES_MAX || vli > LZMA_VLI_MAX)
+		return LZMA_PROG_ERROR;
+
+	// Shift vli so that the next bits to encode are the lowest. In
+	// single-call mode this never changes vli since *vli_pos is zero.
+	vli >>= *vli_pos * 7;
+
+	// Write the non-last bytes in a loop.
+	while (vli >= 0x80) {
+		// We don't need *vli_pos during this function call anymore,
+		// but update it here so that it is ready if we need to
+		// return before the whole integer has been decoded.
+		++*vli_pos;
+		assert(*vli_pos < LZMA_VLI_BYTES_MAX);
+
+		// Write the next byte.
+		out[*out_pos] = (uint8_t)(vli) | 0x80;
+		vli >>= 7;
+
+		if (++*out_pos == out_size)
+			return vli_pos == &vli_pos_internal
+					? LZMA_PROG_ERROR : LZMA_OK;
+	}
+
+	// Write the last byte.
+	out[*out_pos] = (uint8_t)(vli);
+	++*out_pos;
+	++*vli_pos;
+
+	return vli_pos == &vli_pos_internal ? LZMA_OK : LZMA_STREAM_END;
+
+}