56 lines
1.5 KiB
Go
56 lines
1.5 KiB
Go
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package lz4
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// #cgo CFLAGS: -O3
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// #include "src/lz4.h"
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// #include "src/lz4.c"
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import "C"
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import (
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"errors"
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"fmt"
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"unsafe"
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)
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// p gets a char pointer to the first byte of a []byte slice
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func p(in []byte) *C.char {
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if len(in) == 0 {
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return (*C.char)(unsafe.Pointer(nil))
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}
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return (*C.char)(unsafe.Pointer(&in[0]))
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}
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// clen gets the length of a []byte slice as a char *
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func clen(s []byte) C.int {
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return C.int(len(s))
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}
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// Uncompress with a known output size. len(out) should be equal to
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// the length of the uncompressed out.
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func Uncompress(in, out []byte) (error) {
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if int(C.LZ4_decompress_safe(p(in), p(out), clen(in), clen(out))) < 0 {
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return errors.New("Malformed compression stream")
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}
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return nil
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}
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// CompressBound calculates the size of the output buffer needed by
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// Compress. This is based on the following macro:
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//
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// #define LZ4_COMPRESSBOUND(isize)
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// ((unsigned int)(isize) > (unsigned int)LZ4_MAX_INPUT_SIZE ? 0 : (isize) + ((isize)/255) + 16)
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func CompressBound(in []byte) int {
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return len(in) + ((len(in) / 255) + 16)
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}
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// Compress compresses in and puts the content in out. len(out)
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// should have enough space for the compressed data (use CompressBound
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// to calculate). Returns the number of bytes in the out slice.
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func Compress(in, out []byte) (outSize int, err error) {
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outSize = int(C.LZ4_compress_limitedOutput(p(in), p(out), clen(in), clen(out)))
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if outSize == 0 {
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err = fmt.Errorf("insufficient space for compression")
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}
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return
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}
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