mirror of
https://github.com/fumiama/go-base16384.git
synced 2026-06-08 12:00:39 +08:00
316 lines
7.3 KiB
Go
316 lines
7.3 KiB
Go
// Package base14 base16384 的 go 接口
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package base14
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import (
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"encoding/binary"
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"errors"
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)
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func EncodeLen(in int) (out int) {
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out = in / 7 * 8
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offset := in % 7
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switch offset { //算上偏移标志字符占用的2字节
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case 0:
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break
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case 1:
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out += 4
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case 2, 3:
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out += 6
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case 4, 5:
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out += 8
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case 6:
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out += 10
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}
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return
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}
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func Encode(b []byte) (encd []byte) {
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outlen := len(b) / 7 * 8
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offset := len(b) % 7
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switch offset { //算上偏移标志字符占用的2字节
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case 0:
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break
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case 1:
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outlen += 4
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case 2, 3:
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outlen += 6
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case 4, 5:
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outlen += 8
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case 6:
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outlen += 10
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}
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encd = make([]byte, outlen)
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var n int
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i := 0
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b = append(b, 0)
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for ; i <= len(b)-7; i += 7 {
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shift := binary.BigEndian.Uint64(b[i:]) >> 2
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sum := shift
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sum &= 0x3fff000000000000
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shift >>= 2
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sum |= shift & 0x00003fff00000000
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shift >>= 2
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sum |= shift & 0x000000003fff0000
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shift >>= 2
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sum |= shift & 0x0000000000003fff
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sum += 0x4e004e004e004e00
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binary.BigEndian.PutUint64(encd[n:], sum)
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n += 8
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}
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if offset > 0 {
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sum := 0x000000000000003f & ((uint64)(b[i]) >> 2)
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sum |= ((uint64)(b[i]) << 14) & 0x000000000000c000
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if offset > 1 {
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sum |= ((uint64)(b[i+1]) << 6) & 0x0000000000003f00
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sum |= ((uint64)(b[i+1]) << 20) & 0x0000000000300000
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if offset > 2 {
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sum |= ((uint64)(b[i+2]) << 12) & 0x00000000000f0000
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sum |= ((uint64)(b[i+2]) << 28) & 0x00000000f0000000
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if offset > 3 {
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sum |= ((uint64)(b[i+3]) << 20) & 0x000000000f000000
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sum |= ((uint64)(b[i+3]) << 34) & 0x0000003c00000000
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if offset > 4 {
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sum |= ((uint64)(b[i+4]) << 26) & 0x0000000300000000
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sum |= ((uint64)(b[i+4]) << 42) & 0x0000fc0000000000
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if offset > 5 {
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sum |= ((uint64)(b[i+5]) << 34) & 0x0000030000000000
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sum |= ((uint64)(b[i+5]) << 48) & 0x003f000000000000
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}
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}
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}
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}
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}
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sum += 0x004e004e004e004e
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var tmp [8]byte
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binary.LittleEndian.PutUint64(tmp[:], sum)
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copy(encd[n:], tmp[:])
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encd[outlen-2] = '='
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encd[outlen-1] = byte(offset)
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}
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return
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}
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func EncodeTo(b, encd []byte) error {
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outlen := len(b) / 7 * 8
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offset := len(b) % 7
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switch offset { //算上偏移标志字符占用的2字节
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case 0:
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break
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case 1:
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outlen += 4
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case 2, 3:
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outlen += 6
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case 4, 5:
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outlen += 8
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case 6:
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outlen += 10
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}
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if len(encd) < outlen {
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return errors.New("encd too small")
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}
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var n int
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i := 0
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b = append(b, 0)
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for ; i <= len(b)-7; i += 7 {
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shift := binary.BigEndian.Uint64(b[i:]) >> 2
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sum := shift
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sum &= 0x3fff000000000000
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shift >>= 2
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sum |= shift & 0x00003fff00000000
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shift >>= 2
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sum |= shift & 0x000000003fff0000
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shift >>= 2
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sum |= shift & 0x0000000000003fff
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sum += 0x4e004e004e004e00
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binary.BigEndian.PutUint64(encd[n:], sum)
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n += 8
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}
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if offset > 0 {
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sum := 0x000000000000003f & ((uint64)(b[i]) >> 2)
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sum |= ((uint64)(b[i]) << 14) & 0x000000000000c000
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if offset > 1 {
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sum |= ((uint64)(b[i+1]) << 6) & 0x0000000000003f00
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sum |= ((uint64)(b[i+1]) << 20) & 0x0000000000300000
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if offset > 2 {
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sum |= ((uint64)(b[i+2]) << 12) & 0x00000000000f0000
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sum |= ((uint64)(b[i+2]) << 28) & 0x00000000f0000000
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if offset > 3 {
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sum |= ((uint64)(b[i+3]) << 20) & 0x000000000f000000
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sum |= ((uint64)(b[i+3]) << 34) & 0x0000003c00000000
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if offset > 4 {
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sum |= ((uint64)(b[i+4]) << 26) & 0x0000000300000000
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sum |= ((uint64)(b[i+4]) << 42) & 0x0000fc0000000000
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if offset > 5 {
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sum |= ((uint64)(b[i+5]) << 34) & 0x0000030000000000
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sum |= ((uint64)(b[i+5]) << 48) & 0x003f000000000000
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}
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}
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}
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}
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}
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sum += 0x004e004e004e004e
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var tmp [8]byte
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binary.LittleEndian.PutUint64(tmp[:], sum)
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copy(encd[n:], tmp[:])
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encd[outlen-2] = '='
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encd[outlen-1] = byte(offset)
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}
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return nil
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}
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func DecodeLen(in, offset int) (out int) {
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out = in
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switch offset { //算上偏移标志字符占用的2字节
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case 0:
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break
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case 1:
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out -= 4
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case 2, 3:
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out -= 6
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case 4, 5:
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out -= 8
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case 6:
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out -= 10
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}
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out = out/8*7 + offset
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return
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}
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func Decode(b []byte) (decd []byte) {
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outlen := len(b)
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offset := 0
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if b[len(b)-2] == '=' {
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offset = int(b[len(b)-1])
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switch offset { //算上偏移标志字符占用的2字节
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case 0:
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break
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case 1:
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outlen -= 4
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case 2, 3:
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outlen -= 6
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case 4, 5:
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outlen -= 8
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case 6:
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outlen -= 10
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}
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}
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outlen = outlen/8*7 + offset
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decd = make([]byte, outlen)
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var n uintptr
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i := 0
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for ; i <= outlen-7; n += 8 {
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shift := binary.BigEndian.Uint64(b[n:]) - 0x4e004e004e004e00
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shift <<= 2
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sum := shift & 0xfffc000000000000
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shift <<= 2
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sum |= shift & 0x0003fff000000000
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shift <<= 2
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sum |= shift & 0x0000000fffc00000
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shift <<= 2
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sum |= shift & 0x00000000003fff00
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binary.BigEndian.PutUint64(decd[i:], sum)
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i += 7
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}
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if offset > 0 {
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var tmp [8]byte
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copy(tmp[:], b[n:])
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sum := binary.LittleEndian.Uint64(tmp[:]) - 0x000000000000004e
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decd[i] = byte(((sum & 0x000000000000003f) << 2) | ((sum & 0x000000000000c000) >> 14))
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i++
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if offset > 1 {
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sum -= 0x00000000004e0000
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decd[i] = byte(((sum & 0x0000000000003f00) >> 6) | ((sum & 0x0000000000300000) >> 20))
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i++
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if offset > 2 {
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decd[i] = byte(((sum & 0x00000000000f0000) >> 12) | ((sum & 0x00000000f0000000) >> 28))
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i++
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if offset > 3 {
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sum -= 0x0000004e00000000
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decd[i] = byte(((sum & 0x000000000f000000) >> 20) | ((sum & 0x0000003c00000000) >> 34))
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i++
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if offset > 4 {
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decd[i] = byte(((sum & 0x0000000300000000) >> 26) | ((sum & 0x0000fc0000000000) >> 42))
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i++
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if offset > 5 {
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sum -= 0x004e000000000000
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decd[i] = byte(((sum & 0x0000030000000000) >> 34) | ((sum & 0x003f000000000000) >> 48))
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i++
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}
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}
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}
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}
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}
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}
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return
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}
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func DecodeTo(b []byte, decd []byte) error {
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outlen := len(b)
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offset := 0
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if b[len(b)-2] == '=' {
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offset = int(b[len(b)-1])
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switch offset { //算上偏移标志字符占用的2字节
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case 0:
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break
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case 1:
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outlen -= 4
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case 2, 3:
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outlen -= 6
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case 4, 5:
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outlen -= 8
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case 6:
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outlen -= 10
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}
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}
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outlen = outlen/8*7 + offset
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if len(decd) < outlen {
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return errors.New("decd too small")
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}
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var n uintptr
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i := 0
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for ; i <= outlen-7; n += 8 {
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shift := binary.BigEndian.Uint64(b[n:]) - 0x4e004e004e004e00
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shift <<= 2
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sum := shift & 0xfffc000000000000
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shift <<= 2
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sum |= shift & 0x0003fff000000000
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shift <<= 2
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sum |= shift & 0x0000000fffc00000
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shift <<= 2
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sum |= shift & 0x00000000003fff00
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binary.BigEndian.PutUint64(decd[i:], sum)
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i += 7
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}
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if offset > 0 {
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var tmp [8]byte
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copy(tmp[:], b[n:])
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sum := binary.LittleEndian.Uint64(tmp[:]) - 0x000000000000004e
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decd[i] = byte(((sum & 0x000000000000003f) << 2) | ((sum & 0x000000000000c000) >> 14))
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i++
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if offset > 1 {
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sum -= 0x00000000004e0000
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decd[i] = byte(((sum & 0x0000000000003f00) >> 6) | ((sum & 0x0000000000300000) >> 20))
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i++
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if offset > 2 {
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decd[i] = byte(((sum & 0x00000000000f0000) >> 12) | ((sum & 0x00000000f0000000) >> 28))
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i++
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if offset > 3 {
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sum -= 0x0000004e00000000
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decd[i] = byte(((sum & 0x000000000f000000) >> 20) | ((sum & 0x0000003c00000000) >> 34))
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i++
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if offset > 4 {
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decd[i] = byte(((sum & 0x0000000300000000) >> 26) | ((sum & 0x0000fc0000000000) >> 42))
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i++
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if offset > 5 {
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sum -= 0x004e000000000000
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decd[i] = byte(((sum & 0x0000030000000000) >> 34) | ((sum & 0x003f000000000000) >> 48))
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i++
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}
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}
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}
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}
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}
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}
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return nil
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}
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