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authorMichael Niedermayer <michaelni@gmx.at>2015-06-22 20:46:35 +0200
committerMichael Niedermayer <michaelni@gmx.at>2015-06-22 20:47:21 +0200
commit9e5b0f070b690ce5b217970d4eb9cdf7ef6696e5 (patch)
tree04dbd3b2d012706ee13f97d86ded80d827db5d58 /libavcodec/snappy.c
parentf6276842f38d0511a2d2ab4bb7f5b47b195c8de1 (diff)
parent2ecfd451649c7a08cb633635df98e59f7c6e2140 (diff)
downloadffmpeg-9e5b0f070b690ce5b217970d4eb9cdf7ef6696e5.tar.gz
Merge commit '2ecfd451649c7a08cb633635df98e59f7c6e2140'
* commit '2ecfd451649c7a08cb633635df98e59f7c6e2140': Implement Snappy decompression Merged-by: Michael Niedermayer <michaelni@gmx.at>
Diffstat (limited to 'libavcodec/snappy.c')
-rw-r--r--libavcodec/snappy.c173
1 files changed, 173 insertions, 0 deletions
diff --git a/libavcodec/snappy.c b/libavcodec/snappy.c
new file mode 100644
index 0000000000..553d713281
--- /dev/null
+++ b/libavcodec/snappy.c
@@ -0,0 +1,173 @@
+/*
+ * Snappy decompression algorithm
+ * Copyright (c) 2015 Luca Barbato
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg 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.
+ *
+ * FFmpeg 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.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavutil/mem.h"
+
+#include "bytestream.h"
+#include "snappy.h"
+
+enum {
+ SNAPPY_LITERAL,
+ SNAPPY_COPY_1,
+ SNAPPY_COPY_2,
+ SNAPPY_COPY_4,
+};
+
+static int64_t bytestream2_get_levarint(GetByteContext *gb)
+{
+ uint64_t val = 0;
+ int shift = 0;
+ int tmp;
+
+ do {
+ tmp = bytestream2_get_byte(gb);
+ val |= (tmp & 127) << shift;
+ shift += 7;
+ } while (tmp & 128);
+
+ return val;
+}
+
+static int snappy_literal(GetByteContext *gb, uint8_t *p, int size, int val)
+{
+ unsigned int len = 1;
+
+ switch (val) {
+ case 63:
+ len += bytestream2_get_le32(gb);
+ break;
+ case 62:
+ len += bytestream2_get_le24(gb);
+ break;
+ case 61:
+ len += bytestream2_get_le16(gb);
+ break;
+ case 60:
+ len += bytestream2_get_byte(gb);
+ break;
+ default: // val < 60
+ len += val;
+ }
+
+ if (size < len)
+ return AVERROR_INVALIDDATA;
+
+ bytestream2_get_buffer(gb, p, len);
+
+ return len;
+}
+
+static int snappy_copy(uint8_t *start, uint8_t *p, int size,
+ unsigned int off, int len)
+{
+ uint8_t *q;
+ int i;
+ if (off > p - start || size < len)
+ return AVERROR_INVALIDDATA;
+
+ q = p - off;
+
+ for (i = 0; i < len; i++)
+ p[i] = q[i];
+
+ return len;
+}
+
+static int snappy_copy1(GetByteContext *gb, uint8_t *start, uint8_t *p,
+ int size, int val)
+{
+ int len = 4 + (val & 0x7);
+ unsigned int off = bytestream2_get_byte(gb) | (val & 0x38) << 5;
+
+ return snappy_copy(start, p, size, off, len);
+}
+
+static int snappy_copy2(GetByteContext *gb, uint8_t *start, uint8_t *p,
+ int size, int val)
+{
+ int len = 1 + val;
+ unsigned int off = bytestream2_get_le16(gb);
+
+ return snappy_copy(start, p, size, off, len);
+}
+
+static int snappy_copy4(GetByteContext *gb, uint8_t *start, uint8_t *p,
+ int size, int val)
+{
+ int len = 1 + val;
+ unsigned int off = bytestream2_get_le32(gb);
+
+ return snappy_copy(start, p, size, off, len);
+}
+
+static int64_t decode_len(GetByteContext *gb)
+{
+ int64_t len = bytestream2_get_levarint(gb);
+
+ if (len < 0 || len > UINT_MAX)
+ return AVERROR_INVALIDDATA;
+
+ return len;
+}
+
+int ff_snappy_uncompress(GetByteContext *gb, uint8_t **buf, int64_t *size)
+{
+ int64_t len = decode_len(gb);
+ int ret = 0;
+ uint8_t *p;
+
+ if (len < 0)
+ return len;
+
+ if ((ret = av_reallocp(buf, len)) < 0)
+ return AVERROR(ENOMEM);
+
+ *size = len;
+ p = *buf;
+
+ while (bytestream2_get_bytes_left(gb) > 0) {
+ uint8_t s = bytestream2_get_byte(gb);
+ int val = s >> 2;
+
+ switch (s & 0x03) {
+ case SNAPPY_LITERAL:
+ ret = snappy_literal(gb, p, len, val);
+ break;
+ case SNAPPY_COPY_1:
+ ret = snappy_copy1(gb, *buf, p, len, val);
+ break;
+ case SNAPPY_COPY_2:
+ ret = snappy_copy2(gb, *buf, p, len, val);
+ break;
+ case SNAPPY_COPY_4:
+ ret = snappy_copy4(gb, *buf, p, len, val);
+ break;
+ }
+
+ if (ret < 0)
+ return ret;
+
+ p += ret;
+ len -= ret;
+ }
+
+ return 0;
+}