diff options
Diffstat (limited to 'libgo/go/strconv/ftoa.go')
| -rw-r--r-- | libgo/go/strconv/ftoa.go | 108 |
1 files changed, 44 insertions, 64 deletions
diff --git a/libgo/go/strconv/ftoa.go b/libgo/go/strconv/ftoa.go index 1a9c41b85a8..468c37fafb9 100644 --- a/libgo/go/strconv/ftoa.go +++ b/libgo/go/strconv/ftoa.go @@ -47,7 +47,7 @@ func FormatFloat(f float64, fmt byte, prec, bitSize int) string { // AppendFloat appends the string form of the floating-point number f, // as generated by FormatFloat, to dst and returns the extended buffer. -func AppendFloat(dst []byte, f float64, fmt byte, prec int, bitSize int) []byte { +func AppendFloat(dst []byte, f float64, fmt byte, prec, bitSize int) []byte { return genericFtoa(dst, f, fmt, prec, bitSize) } @@ -119,7 +119,7 @@ func genericFtoa(dst []byte, val float64, fmt byte, prec, bitSize int) []byte { // Precision for shortest representation mode. switch fmt { case 'e', 'E': - prec = digs.nd - 1 + prec = max(digs.nd-1, 0) case 'f': prec = max(digs.nd-digs.dp, 0) case 'g', 'G': @@ -223,9 +223,8 @@ func formatDigits(dst []byte, shortest bool, neg bool, digs decimalSlice, prec i return append(dst, '%', fmt) } -// Round d (= mant * 2^exp) to the shortest number of digits -// that will let the original floating point value be precisely -// reconstructed. Size is original floating point size (64 or 32). +// roundShortest rounds d (= mant * 2^exp) to the shortest number of digits +// that will let the original floating point value be precisely reconstructed. func roundShortest(d *decimal, mant uint64, exp int, flt *floatInfo) { // If mantissa is zero, the number is zero; stop now. if mant == 0 { @@ -348,14 +347,13 @@ func fmtE(dst []byte, neg bool, d decimalSlice, prec int, fmt byte) []byte { if prec > 0 { dst = append(dst, '.') i := 1 - m := d.nd + prec + 1 - max(d.nd, prec+1) - for i < m { - dst = append(dst, d.d[i]) - i++ + m := min(d.nd, prec+1) + if i < m { + dst = append(dst, d.d[i:m]...) + i = m } - for i <= prec { + for ; i <= prec; i++ { dst = append(dst, '0') - i++ } } @@ -373,27 +371,16 @@ func fmtE(dst []byte, neg bool, d decimalSlice, prec int, fmt byte) []byte { } dst = append(dst, ch) - // dddd - var buf [3]byte - i := len(buf) - for exp >= 10 { - i-- - buf[i] = byte(exp%10 + '0') - exp /= 10 + // dd or ddd + switch { + case exp < 10: + dst = append(dst, '0', byte(exp)+'0') + case exp < 100: + dst = append(dst, byte(exp/10)+'0', byte(exp%10)+'0') + default: + dst = append(dst, byte(exp/100)+'0', byte(exp/10)%10+'0', byte(exp%10)+'0') } - // exp < 10 - i-- - buf[i] = byte(exp + '0') - switch i { - case 0: - dst = append(dst, buf[0], buf[1], buf[2]) - case 1: - dst = append(dst, buf[1], buf[2]) - case 2: - // leading zeroes - dst = append(dst, '0', buf[2]) - } return dst } @@ -406,11 +393,9 @@ func fmtF(dst []byte, neg bool, d decimalSlice, prec int) []byte { // integer, padded with zeros as needed. if d.dp > 0 { - var i int - for i = 0; i < d.dp && i < d.nd; i++ { - dst = append(dst, d.d[i]) - } - for ; i < d.dp; i++ { + m := min(d.nd, d.dp) + dst = append(dst, d.d[:m]...) + for ; m < d.dp; m++ { dst = append(dst, '0') } } else { @@ -432,39 +417,34 @@ func fmtF(dst []byte, neg bool, d decimalSlice, prec int) []byte { return dst } -// %b: -ddddddddp+ddd +// %b: -ddddddddp±ddd func fmtB(dst []byte, neg bool, mant uint64, exp int, flt *floatInfo) []byte { - var buf [50]byte - w := len(buf) - exp -= int(flt.mantbits) - esign := byte('+') - if exp < 0 { - esign = '-' - exp = -exp - } - n := 0 - for exp > 0 || n < 1 { - n++ - w-- - buf[w] = byte(exp%10 + '0') - exp /= 10 + // sign + if neg { + dst = append(dst, '-') } - w-- - buf[w] = esign - w-- - buf[w] = 'p' - n = 0 - for mant > 0 || n < 1 { - n++ - w-- - buf[w] = byte(mant%10 + '0') - mant /= 10 + + // mantissa + dst, _ = formatBits(dst, mant, 10, false, true) + + // p + dst = append(dst, 'p') + + // ±exponent + exp -= int(flt.mantbits) + if exp >= 0 { + dst = append(dst, '+') } - if neg { - w-- - buf[w] = '-' + dst, _ = formatBits(dst, uint64(exp), 10, exp < 0, true) + + return dst +} + +func min(a, b int) int { + if a < b { + return a } - return append(dst, buf[w:]...) + return b } func max(a, b int) int { |