mirror of
https://github.com/VictoriaMetrics/VictoriaMetrics.git
synced 2024-12-23 08:56:31 +01:00
113 lines
3.4 KiB
Go
113 lines
3.4 KiB
Go
// Copyright 2018 Klaus Post. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
// Based on work Copyright (c) 2013, Yann Collet, released under BSD License.
|
|
|
|
package zstd
|
|
|
|
// bitWriter will write bits.
|
|
// First bit will be LSB of the first byte of output.
|
|
type bitWriter struct {
|
|
bitContainer uint64
|
|
nBits uint8
|
|
out []byte
|
|
}
|
|
|
|
// bitMask16 is bitmasks. Has extra to avoid bounds check.
|
|
var bitMask16 = [32]uint16{
|
|
0, 1, 3, 7, 0xF, 0x1F,
|
|
0x3F, 0x7F, 0xFF, 0x1FF, 0x3FF, 0x7FF,
|
|
0xFFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF, 0xFFFF,
|
|
0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
|
|
0xFFFF, 0xFFFF} /* up to 16 bits */
|
|
|
|
var bitMask32 = [32]uint32{
|
|
0, 1, 3, 7, 0xF, 0x1F, 0x3F, 0x7F, 0xFF,
|
|
0x1FF, 0x3FF, 0x7FF, 0xFFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF,
|
|
0x1ffff, 0x3ffff, 0x7FFFF, 0xfFFFF, 0x1fFFFF, 0x3fFFFF, 0x7fFFFF, 0xffFFFF,
|
|
0x1ffFFFF, 0x3ffFFFF, 0x7ffFFFF, 0xfffFFFF, 0x1fffFFFF, 0x3fffFFFF, 0x7fffFFFF,
|
|
} // up to 32 bits
|
|
|
|
// addBits16NC will add up to 16 bits.
|
|
// It will not check if there is space for them,
|
|
// so the caller must ensure that it has flushed recently.
|
|
func (b *bitWriter) addBits16NC(value uint16, bits uint8) {
|
|
b.bitContainer |= uint64(value&bitMask16[bits&31]) << (b.nBits & 63)
|
|
b.nBits += bits
|
|
}
|
|
|
|
// addBits32NC will add up to 31 bits.
|
|
// It will not check if there is space for them,
|
|
// so the caller must ensure that it has flushed recently.
|
|
func (b *bitWriter) addBits32NC(value uint32, bits uint8) {
|
|
b.bitContainer |= uint64(value&bitMask32[bits&31]) << (b.nBits & 63)
|
|
b.nBits += bits
|
|
}
|
|
|
|
// addBits64NC will add up to 64 bits.
|
|
// There must be space for 32 bits.
|
|
func (b *bitWriter) addBits64NC(value uint64, bits uint8) {
|
|
if bits <= 31 {
|
|
b.addBits32Clean(uint32(value), bits)
|
|
return
|
|
}
|
|
b.addBits32Clean(uint32(value), 32)
|
|
b.flush32()
|
|
b.addBits32Clean(uint32(value>>32), bits-32)
|
|
}
|
|
|
|
// addBits32Clean will add up to 32 bits.
|
|
// It will not check if there is space for them.
|
|
// The input must not contain more bits than specified.
|
|
func (b *bitWriter) addBits32Clean(value uint32, bits uint8) {
|
|
b.bitContainer |= uint64(value) << (b.nBits & 63)
|
|
b.nBits += bits
|
|
}
|
|
|
|
// addBits16Clean will add up to 16 bits. value may not contain more set bits than indicated.
|
|
// It will not check if there is space for them, so the caller must ensure that it has flushed recently.
|
|
func (b *bitWriter) addBits16Clean(value uint16, bits uint8) {
|
|
b.bitContainer |= uint64(value) << (b.nBits & 63)
|
|
b.nBits += bits
|
|
}
|
|
|
|
// flush32 will flush out, so there are at least 32 bits available for writing.
|
|
func (b *bitWriter) flush32() {
|
|
if b.nBits < 32 {
|
|
return
|
|
}
|
|
b.out = append(b.out,
|
|
byte(b.bitContainer),
|
|
byte(b.bitContainer>>8),
|
|
byte(b.bitContainer>>16),
|
|
byte(b.bitContainer>>24))
|
|
b.nBits -= 32
|
|
b.bitContainer >>= 32
|
|
}
|
|
|
|
// flushAlign will flush remaining full bytes and align to next byte boundary.
|
|
func (b *bitWriter) flushAlign() {
|
|
nbBytes := (b.nBits + 7) >> 3
|
|
for i := uint8(0); i < nbBytes; i++ {
|
|
b.out = append(b.out, byte(b.bitContainer>>(i*8)))
|
|
}
|
|
b.nBits = 0
|
|
b.bitContainer = 0
|
|
}
|
|
|
|
// close will write the alignment bit and write the final byte(s)
|
|
// to the output.
|
|
func (b *bitWriter) close() {
|
|
// End mark
|
|
b.addBits16Clean(1, 1)
|
|
// flush until next byte.
|
|
b.flushAlign()
|
|
}
|
|
|
|
// reset and continue writing by appending to out.
|
|
func (b *bitWriter) reset(out []byte) {
|
|
b.bitContainer = 0
|
|
b.nBits = 0
|
|
b.out = out
|
|
}
|