80 lines
1.7 KiB
Go
80 lines
1.7 KiB
Go
// Copyright 2014-2019 Ulrich Kunitz. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package xz
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import (
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"errors"
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"io"
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)
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// putUint32LE puts the little-endian representation of x into the first
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// four bytes of p.
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func putUint32LE(p []byte, x uint32) {
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p[0] = byte(x)
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p[1] = byte(x >> 8)
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p[2] = byte(x >> 16)
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p[3] = byte(x >> 24)
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}
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// putUint64LE puts the little-endian representation of x into the first
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// eight bytes of p.
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func putUint64LE(p []byte, x uint64) {
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p[0] = byte(x)
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p[1] = byte(x >> 8)
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p[2] = byte(x >> 16)
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p[3] = byte(x >> 24)
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p[4] = byte(x >> 32)
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p[5] = byte(x >> 40)
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p[6] = byte(x >> 48)
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p[7] = byte(x >> 56)
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}
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// uint32LE converts a little endian representation to an uint32 value.
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func uint32LE(p []byte) uint32 {
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return uint32(p[0]) | uint32(p[1])<<8 | uint32(p[2])<<16 |
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uint32(p[3])<<24
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}
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// putUvarint puts a uvarint representation of x into the byte slice.
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func putUvarint(p []byte, x uint64) int {
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i := 0
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for x >= 0x80 {
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p[i] = byte(x) | 0x80
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x >>= 7
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i++
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}
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p[i] = byte(x)
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return i + 1
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}
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// errOverflow indicates an overflow of the 64-bit unsigned integer.
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var errOverflowU64 = errors.New("xz: uvarint overflows 64-bit unsigned integer")
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// readUvarint reads a uvarint from the given byte reader.
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func readUvarint(r io.ByteReader) (x uint64, n int, err error) {
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const maxUvarintLen = 10
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var s uint
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i := 0
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for {
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b, err := r.ReadByte()
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if err != nil {
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return x, i, err
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}
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i++
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if i > maxUvarintLen {
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return x, i, errOverflowU64
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}
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if b < 0x80 {
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if i == maxUvarintLen && b > 1 {
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return x, i, errOverflowU64
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}
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return x | uint64(b)<<s, i, nil
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}
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x |= uint64(b&0x7f) << s
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s += 7
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}
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}
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