764e469ada
Co-authored-by: eMeab <32988354+eMeab@users.noreply.github.com> Co-authored-by: Dreamacro <8615343+Dreamacro@users.noreply.github.com>
58 lines
1.5 KiB
Go
58 lines
1.5 KiB
Go
// Copy from: https://github.com/Equim-chan/leb128
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// License: BSD-3-Clause
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package gun
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var sevenbits = [...]byte{
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0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
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0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
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0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
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0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
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0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f,
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0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,
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0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
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0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f,
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}
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func decodeUleb128(b []byte) (u uint64, n uint8) {
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l := uint8(len(b) & 0xff)
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// The longest LEB128 encoded sequence is 10 byte long (9 0xff's and 1 0x7f)
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// so make sure we won't overflow.
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if l > 10 {
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l = 10
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}
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var i uint8
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for i = 0; i < l; i++ {
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u |= uint64(b[i]&0x7f) << (7 * i)
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if b[i]&0x80 == 0 {
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n = uint8(i + 1)
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return
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}
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}
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return
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}
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func appendUleb128(b []byte, v uint64) []byte {
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// If it's less than or equal to 7-bit
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if v < 0x80 {
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return append(b, sevenbits[v])
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}
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for {
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c := uint8(v & 0x7f)
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v >>= 7
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if v != 0 {
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c |= 0x80
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}
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b = append(b, c)
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if c&0x80 == 0 {
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break
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}
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}
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return b
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}
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