bytesconv.go
func ParseUfloat(buf []byte) (float64, error) {
	if len(buf) == 0 {
		return -1, errEmptyFloat
	}
	b := buf
	var v uint64
	var offset = 1.0
	var pointFound bool
	for i, c := range b {
		if c < '0' || c > '9' {
			if c == '.' {
				if pointFound {
					return -1, errDuplicateFloatPoint
				}
				pointFound = true
				continue
			}
			if c == 'e' || c == 'E' {
				if i+1 >= len(b) {
					return -1, errUnexpectedFloatEnd
				}
				b = b[i+1:]
				minus := -1
				switch b[0] {
				case '+':
					b = b[1:]
					minus = 1
				case '-':
					b = b[1:]
				default:
					minus = 1
				}
				vv, err := ParseUint(b)
				if err != nil {
					return -1, errInvalidFloatExponent
				}
				return float64(v) * offset * math.Pow10(minus*int(vv)), nil
			}
			return -1, errUnexpectedFloatChar
		}
		v = 10*v + uint64(c-'0')
		if pointFound {
			offset /= 10
		}
	}
	return float64(v) * offset, nil
}
func ParseUfloat(buf []byte) (float64, error) {
	if len(buf) == 0 {
		return -1, errEmptyFloat
	}
	b := buf
	var v uint64
	var offset = 1.0
	var pointFound bool
	for i, c := range b {
		if c < '0' || c > '9' {
			if c == '.' {
				if pointFound {
					return -1, errDuplicateFloatPoint
				}
				pointFound = true
				continue
			}
			if c == 'e' || c == 'E' {
				if i+1 >= len(b) {
					return -1, errUnexpectedFloatEnd
				}
				b = b[i+1:]
				minus := -1
				switch b[0] {
				case '+':
					b = b[1:]
					minus = 1
				case '-':
					b = b[1:]
				default:
					minus = 1
				}
				vv, err := ParseUint(b)
				if err != nil {
					return -1, errInvalidFloatExponent
				}
				return float64(v) * offset * math.Pow10(minus*int(vv)), nil
			}
			return -1, errUnexpectedFloatChar
		}
		v = 10*v + uint64(c-'0')
		if pointFound {
			offset /= 10
		}
	}
	return float64(v) * offset, nil
}
// ParseUfloat parses unsigned float from buf.