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author | Wim <wim@42.be> | 2020-10-19 23:40:00 +0200 |
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committer | GitHub <noreply@github.com> | 2020-10-19 23:40:00 +0200 |
commit | 075a84427f6332aab707d283ad770d69f8816032 (patch) | |
tree | 0ff9f56a057919f3fe968e57f6f0b1c0d1f85078 /vendor/github.com/go-asn1-ber/asn1-ber/real.go | |
parent | 950f2759bd2b20aa0bdedc3dc9a74d0dafb606d8 (diff) | |
download | matterbridge-msglm-075a84427f6332aab707d283ad770d69f8816032.tar.gz matterbridge-msglm-075a84427f6332aab707d283ad770d69f8816032.tar.bz2 matterbridge-msglm-075a84427f6332aab707d283ad770d69f8816032.zip |
Update vendor (#1265)
Diffstat (limited to 'vendor/github.com/go-asn1-ber/asn1-ber/real.go')
-rw-r--r-- | vendor/github.com/go-asn1-ber/asn1-ber/real.go | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/vendor/github.com/go-asn1-ber/asn1-ber/real.go b/vendor/github.com/go-asn1-ber/asn1-ber/real.go new file mode 100644 index 00000000..610a003a --- /dev/null +++ b/vendor/github.com/go-asn1-ber/asn1-ber/real.go @@ -0,0 +1,157 @@ +package ber + +import ( + "bytes" + "errors" + "fmt" + "math" + "strconv" + "strings" +) + +func encodeFloat(v float64) []byte { + switch { + case math.IsInf(v, 1): + return []byte{0x40} + case math.IsInf(v, -1): + return []byte{0x41} + case math.IsNaN(v): + return []byte{0x42} + case v == 0.0: + if math.Signbit(v) { + return []byte{0x43} + } + return []byte{} + default: + // we take the easy part ;-) + value := []byte(strconv.FormatFloat(v, 'G', -1, 64)) + var ret []byte + if bytes.Contains(value, []byte{'E'}) { + ret = []byte{0x03} + } else { + ret = []byte{0x02} + } + ret = append(ret, value...) + return ret + } +} + +func ParseReal(v []byte) (val float64, err error) { + if len(v) == 0 { + return 0.0, nil + } + switch { + case v[0]&0x80 == 0x80: + val, err = parseBinaryFloat(v) + case v[0]&0xC0 == 0x40: + val, err = parseSpecialFloat(v) + case v[0]&0xC0 == 0x0: + val, err = parseDecimalFloat(v) + default: + return 0.0, fmt.Errorf("invalid info block") + } + if err != nil { + return 0.0, err + } + + if val == 0.0 && !math.Signbit(val) { + return 0.0, errors.New("REAL value +0 must be encoded with zero-length value block") + } + return val, nil +} + +func parseBinaryFloat(v []byte) (float64, error) { + var info byte + var buf []byte + + info, v = v[0], v[1:] + + var base int + switch info & 0x30 { + case 0x00: + base = 2 + case 0x10: + base = 8 + case 0x20: + base = 16 + case 0x30: + return 0.0, errors.New("bits 6 and 5 of information octet for REAL are equal to 11") + } + + scale := uint((info & 0x0c) >> 2) + + var expLen int + switch info & 0x03 { + case 0x00: + expLen = 1 + case 0x01: + expLen = 2 + case 0x02: + expLen = 3 + case 0x03: + expLen = int(v[0]) + if expLen > 8 { + return 0.0, errors.New("too big value of exponent") + } + v = v[1:] + } + buf, v = v[:expLen], v[expLen:] + exponent, err := ParseInt64(buf) + if err != nil { + return 0.0, err + } + + if len(v) > 8 { + return 0.0, errors.New("too big value of mantissa") + } + + mant, err := ParseInt64(v) + if err != nil { + return 0.0, err + } + mantissa := mant << scale + + if info&0x40 == 0x40 { + mantissa = -mantissa + } + + return float64(mantissa) * math.Pow(float64(base), float64(exponent)), nil +} + +func parseDecimalFloat(v []byte) (val float64, err error) { + switch v[0] & 0x3F { + case 0x01: // NR form 1 + var iVal int64 + iVal, err = strconv.ParseInt(strings.TrimLeft(string(v[1:]), " "), 10, 64) + val = float64(iVal) + case 0x02, 0x03: // NR form 2, 3 + val, err = strconv.ParseFloat(strings.Replace(strings.TrimLeft(string(v[1:]), " "), ",", ".", -1), 64) + default: + err = errors.New("incorrect NR form") + } + if err != nil { + return 0.0, err + } + + if val == 0.0 && math.Signbit(val) { + return 0.0, errors.New("REAL value -0 must be encoded as a special value") + } + return val, nil +} + +func parseSpecialFloat(v []byte) (float64, error) { + if len(v) != 1 { + return 0.0, errors.New(`encoding of "special value" must not contain exponent and mantissa`) + } + switch v[0] { + case 0x40: + return math.Inf(1), nil + case 0x41: + return math.Inf(-1), nil + case 0x42: + return math.NaN(), nil + case 0x43: + return math.Copysign(0, -1), nil + } + return 0.0, errors.New(`encoding of "special value" not from ASN.1 standard`) +} |