hex.go

package winguid

const hextable = "0123456789ABCDEF"

func decodeHexUint32(src []byte) (value uint32, ok bool) {
	var b1, b2, b3, b4 byte
	var ok1, ok2, ok3, ok4 bool
	b1, ok1 = decodeHexByte(src[0], src[1])
	b2, ok2 = decodeHexByte(src[2], src[3])
	b3, ok3 = decodeHexByte(src[4], src[5])
	b4, ok4 = decodeHexByte(src[6], src[7])
	value = (uint32(b1) << 24) | (uint32(b2) << 16) | (uint32(b3) << 8) | uint32(b4)
	ok = ok1 && ok2 && ok3 && ok4
	return
}

func decodeHexUint16(src []byte) (value uint16, ok bool) {
	var b1, b2 byte
	var ok1, ok2 bool
	b1, ok1 = decodeHexByte(src[0], src[1])
	b2, ok2 = decodeHexByte(src[2], src[3])
	value = (uint16(b1) << 8) | uint16(b2)
	ok = ok1 && ok2
	return
}

func decodeHexByte64(s1 []byte, s2 []byte) (value [8]byte, ok bool) {
	var ok1, ok2, ok3, ok4, ok5, ok6, ok7, ok8 bool
	value[0], ok1 = decodeHexByte(s1[0], s1[1])
	value[1], ok2 = decodeHexByte(s1[2], s1[3])
	value[2], ok3 = decodeHexByte(s2[0], s2[1])
	value[3], ok4 = decodeHexByte(s2[2], s2[3])
	value[4], ok5 = decodeHexByte(s2[4], s2[5])
	value[5], ok6 = decodeHexByte(s2[6], s2[7])
	value[6], ok7 = decodeHexByte(s2[8], s2[9])
	value[7], ok8 = decodeHexByte(s2[10], s2[11])
	ok = ok1 && ok2 && ok3 && ok4 && ok5 && ok6 && ok7 && ok8
	return
}

func decodeHexByte(c1, c2 byte) (value byte, ok bool) {
	var n1, n2 byte
	var ok1, ok2 bool
	n1, ok1 = decodeHexChar(c1)
	n2, ok2 = decodeHexChar(c2)
	value = (n1 << 4) | n2
	ok = ok1 && ok2
	return
}

func decodeHexChar(c byte) (byte, bool) {
	switch {
	case '0' <= c && c <= '9':
		return c - '0', true
	case 'a' <= c && c <= 'f':
		return c - 'a' + 10, true
	case 'A' <= c && c <= 'F':
		return c - 'A' + 10, true
	}

	return 0, false
}

func putUint32Hex(b []byte, v uint32) {
	b[0] = hextable[byte(v>>24)>>4]
	b[1] = hextable[byte(v>>24)&0x0f]
	b[2] = hextable[byte(v>>16)>>4]
	b[3] = hextable[byte(v>>16)&0x0f]
	b[4] = hextable[byte(v>>8)>>4]
	b[5] = hextable[byte(v>>8)&0x0f]
	b[6] = hextable[byte(v)>>4]
	b[7] = hextable[byte(v)&0x0f]
}

func putUint16Hex(b []byte, v uint16) {
	b[0] = hextable[byte(v>>8)>>4]
	b[1] = hextable[byte(v>>8)&0x0f]
	b[2] = hextable[byte(v)>>4]
	b[3] = hextable[byte(v)&0x0f]
}

func putByteHex(dst, src []byte) {
	for i := 0; i < len(src); i++ {
		dst[i*2] = hextable[src[i]>>4]
		dst[i*2+1] = hextable[src[i]&0x0f]
	}
}