diff options
Diffstat (limited to 'vendor/github.com/klauspost/compress/zstd/bitreader.go')
| -rw-r--r-- | vendor/github.com/klauspost/compress/zstd/bitreader.go | 25 |
1 files changed, 20 insertions, 5 deletions
diff --git a/vendor/github.com/klauspost/compress/zstd/bitreader.go b/vendor/github.com/klauspost/compress/zstd/bitreader.go index 15d79d439..854458537 100644 --- a/vendor/github.com/klauspost/compress/zstd/bitreader.go +++ b/vendor/github.com/klauspost/compress/zstd/bitreader.go @@ -5,6 +5,7 @@ package zstd import ( + "encoding/binary" "errors" "io" "math/bits" @@ -34,8 +35,12 @@ func (b *bitReader) init(in []byte) error { } b.bitsRead = 64 b.value = 0 - b.fill() - b.fill() + if len(in) >= 8 { + b.fillFastStart() + } else { + b.fill() + b.fill() + } b.bitsRead += 8 - uint8(highBits(uint32(v))) return nil } @@ -63,21 +68,31 @@ func (b *bitReader) fillFast() { if b.bitsRead < 32 { return } - // Do single re-slice to avoid bounds checks. - v := b.in[b.off-4 : b.off] + // 2 bounds checks. + v := b.in[b.off-4:] + v = v[:4] low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24) b.value = (b.value << 32) | uint64(low) b.bitsRead -= 32 b.off -= 4 } +// fillFastStart() assumes the bitreader is empty and there is at least 8 bytes to read. +func (b *bitReader) fillFastStart() { + // Do single re-slice to avoid bounds checks. + b.value = binary.LittleEndian.Uint64(b.in[b.off-8:]) + b.bitsRead = 0 + b.off -= 8 +} + // fill() will make sure at least 32 bits are available. func (b *bitReader) fill() { if b.bitsRead < 32 { return } if b.off >= 4 { - v := b.in[b.off-4 : b.off] + v := b.in[b.off-4:] + v = v[:4] low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24) b.value = (b.value << 32) | uint64(low) b.bitsRead -= 32 |