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// Copyright 2014 The zappy Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Copyright 2011 The Snappy-Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the SNAPPY-GO-LICENSE file.
// +build cgo,!purego
package zappy
/*
#include <stdint.h>
#include <string.h>
// supports only uint32 encoded values
int uvarint(unsigned int* n, uint8_t* src, int len) {
int r = 0;
unsigned int v = 0;
unsigned int s = 0;
while ((len-- != 0) && (++r <= 5)) {
uint8_t b = *src++;
v = v | ((b&0x7f)<<s);
if (b < 0x80) {
*n = v;
return r;
}
s += 7;
}
return -1;
}
int varint(int* n, uint8_t* src, int len) {
unsigned int u;
int i = uvarint(&u, src, len);
int x = u>>1;
if ((u&1) != 0)
x = ~x;
*n = x;
return i;
}
int decode(int s, int len_src, uint8_t* src, int len_dst, uint8_t* dst) {
int d = 0;
int length;
while (s < len_src) {
int n, i = varint(&n, src+s, len_src-s);
if (i <= 0) {
return -1;
}
s += i;
if (n >= 0) {
length = n+1;
if ((length > len_dst-d) || (length > len_src-s))
return -1;
memcpy(dst+d, src+s, length);
d += length;
s += length;
continue;
}
length = -n;
int offset;
i = uvarint((unsigned int*)(&offset), src+s, len_src-s);
if (i <= 0)
return -1;
s += i;
if (s > len_src)
return -1;
int end = d+length;
if ((offset > d) || (end > len_dst))
return -1;
for( ; d < end; d++)
*(dst+d) = *(dst+d-offset);
}
return d;
}
*/
import "C"
func puregoDecode() bool { return false }
// Decode returns the decoded form of src. The returned slice may be a sub-
// slice of buf if buf was large enough to hold the entire decoded block.
// Otherwise, a newly allocated slice will be returned.
// It is valid to pass a nil buf.
func Decode(buf, src []byte) ([]byte, error) {
dLen, s, err := decodedLen(src)
if err != nil {
return nil, err
}
if dLen == 0 {
if len(src) == 1 {
return nil, nil
}
return nil, ErrCorrupt
}
if len(buf) < dLen {
buf = make([]byte, dLen)
}
d := int(C.decode(C.int(s), C.int(len(src)), (*C.uint8_t)(&src[0]), C.int(len(buf)), (*C.uint8_t)(&buf[0])))
if d != dLen {
return nil, ErrCorrupt
}
return buf[:d], nil
}
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