diff options
Diffstat (limited to 'vendor/github.com/pquerna/ffjson/fflib/v1/ftoa.go')
| -rw-r--r-- | vendor/github.com/pquerna/ffjson/fflib/v1/ftoa.go | 542 |
1 files changed, 0 insertions, 542 deletions
diff --git a/vendor/github.com/pquerna/ffjson/fflib/v1/ftoa.go b/vendor/github.com/pquerna/ffjson/fflib/v1/ftoa.go deleted file mode 100644 index 360d6dbcf..000000000 --- a/vendor/github.com/pquerna/ffjson/fflib/v1/ftoa.go +++ /dev/null @@ -1,542 +0,0 @@ -package v1 - -/** - * Copyright 2015 Paul Querna, Klaus Post - * - * Licensed under the Apache License, Version 2.0 (the "License"); - * you may not use this file except in compliance with the License. - * You may obtain a copy of the License at - * - * http://www.apache.org/licenses/LICENSE-2.0 - * - * Unless required by applicable law or agreed to in writing, software - * distributed under the License is distributed on an "AS IS" BASIS, - * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. - * See the License for the specific language governing permissions and - * limitations under the License. - * - */ - -/* Most of this file are on Go stdlib's strconv/ftoa.go */ -// Copyright 2009 The Go Authors. All rights reserved. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -import "math" - -// TODO: move elsewhere? -type floatInfo struct { - mantbits uint - expbits uint - bias int -} - -var optimize = true // can change for testing - -var float32info = floatInfo{23, 8, -127} -var float64info = floatInfo{52, 11, -1023} - -// AppendFloat appends the string form of the floating-point number f, -// as generated by FormatFloat -func AppendFloat(dst EncodingBuffer, val float64, fmt byte, prec, bitSize int) { - var bits uint64 - var flt *floatInfo - switch bitSize { - case 32: - bits = uint64(math.Float32bits(float32(val))) - flt = &float32info - case 64: - bits = math.Float64bits(val) - flt = &float64info - default: - panic("strconv: illegal AppendFloat/FormatFloat bitSize") - } - - neg := bits>>(flt.expbits+flt.mantbits) != 0 - exp := int(bits>>flt.mantbits) & (1<<flt.expbits - 1) - mant := bits & (uint64(1)<<flt.mantbits - 1) - - switch exp { - case 1<<flt.expbits - 1: - // Inf, NaN - var s string - switch { - case mant != 0: - s = "NaN" - case neg: - s = "-Inf" - default: - s = "+Inf" - } - dst.WriteString(s) - return - - case 0: - // denormalized - exp++ - - default: - // add implicit top bit - mant |= uint64(1) << flt.mantbits - } - exp += flt.bias - - // Pick off easy binary format. - if fmt == 'b' { - fmtB(dst, neg, mant, exp, flt) - return - } - - if !optimize { - bigFtoa(dst, prec, fmt, neg, mant, exp, flt) - return - } - - var digs decimalSlice - ok := false - // Negative precision means "only as much as needed to be exact." - shortest := prec < 0 - if shortest { - // Try Grisu3 algorithm. - f := new(extFloat) - lower, upper := f.AssignComputeBounds(mant, exp, neg, flt) - var buf [32]byte - digs.d = buf[:] - ok = f.ShortestDecimal(&digs, &lower, &upper) - if !ok { - bigFtoa(dst, prec, fmt, neg, mant, exp, flt) - return - } - // Precision for shortest representation mode. - switch fmt { - case 'e', 'E': - prec = max(digs.nd-1, 0) - case 'f': - prec = max(digs.nd-digs.dp, 0) - case 'g', 'G': - prec = digs.nd - } - } else if fmt != 'f' { - // Fixed number of digits. - digits := prec - switch fmt { - case 'e', 'E': - digits++ - case 'g', 'G': - if prec == 0 { - prec = 1 - } - digits = prec - } - if digits <= 15 { - // try fast algorithm when the number of digits is reasonable. - var buf [24]byte - digs.d = buf[:] - f := extFloat{mant, exp - int(flt.mantbits), neg} - ok = f.FixedDecimal(&digs, digits) - } - } - if !ok { - bigFtoa(dst, prec, fmt, neg, mant, exp, flt) - return - } - formatDigits(dst, shortest, neg, digs, prec, fmt) - return -} - -// bigFtoa uses multiprecision computations to format a float. -func bigFtoa(dst EncodingBuffer, prec int, fmt byte, neg bool, mant uint64, exp int, flt *floatInfo) { - d := new(decimal) - d.Assign(mant) - d.Shift(exp - int(flt.mantbits)) - var digs decimalSlice - shortest := prec < 0 - if shortest { - roundShortest(d, mant, exp, flt) - digs = decimalSlice{d: d.d[:], nd: d.nd, dp: d.dp} - // Precision for shortest representation mode. - switch fmt { - case 'e', 'E': - prec = digs.nd - 1 - case 'f': - prec = max(digs.nd-digs.dp, 0) - case 'g', 'G': - prec = digs.nd - } - } else { - // Round appropriately. - switch fmt { - case 'e', 'E': - d.Round(prec + 1) - case 'f': - d.Round(d.dp + prec) - case 'g', 'G': - if prec == 0 { - prec = 1 - } - d.Round(prec) - } - digs = decimalSlice{d: d.d[:], nd: d.nd, dp: d.dp} - } - formatDigits(dst, shortest, neg, digs, prec, fmt) - return -} - -func formatDigits(dst EncodingBuffer, shortest bool, neg bool, digs decimalSlice, prec int, fmt byte) { - switch fmt { - case 'e', 'E': - fmtE(dst, neg, digs, prec, fmt) - return - case 'f': - fmtF(dst, neg, digs, prec) - return - case 'g', 'G': - // trailing fractional zeros in 'e' form will be trimmed. - eprec := prec - if eprec > digs.nd && digs.nd >= digs.dp { - eprec = digs.nd - } - // %e is used if the exponent from the conversion - // is less than -4 or greater than or equal to the precision. - // if precision was the shortest possible, use precision 6 for this decision. - if shortest { - eprec = 6 - } - exp := digs.dp - 1 - if exp < -4 || exp >= eprec { - if prec > digs.nd { - prec = digs.nd - } - fmtE(dst, neg, digs, prec-1, fmt+'e'-'g') - return - } - if prec > digs.dp { - prec = digs.nd - } - fmtF(dst, neg, digs, max(prec-digs.dp, 0)) - return - } - - // unknown format - dst.Write([]byte{'%', fmt}) - return -} - -// 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). -func roundShortest(d *decimal, mant uint64, exp int, flt *floatInfo) { - // If mantissa is zero, the number is zero; stop now. - if mant == 0 { - d.nd = 0 - return - } - - // Compute upper and lower such that any decimal number - // between upper and lower (possibly inclusive) - // will round to the original floating point number. - - // We may see at once that the number is already shortest. - // - // Suppose d is not denormal, so that 2^exp <= d < 10^dp. - // The closest shorter number is at least 10^(dp-nd) away. - // The lower/upper bounds computed below are at distance - // at most 2^(exp-mantbits). - // - // So the number is already shortest if 10^(dp-nd) > 2^(exp-mantbits), - // or equivalently log2(10)*(dp-nd) > exp-mantbits. - // It is true if 332/100*(dp-nd) >= exp-mantbits (log2(10) > 3.32). - minexp := flt.bias + 1 // minimum possible exponent - if exp > minexp && 332*(d.dp-d.nd) >= 100*(exp-int(flt.mantbits)) { - // The number is already shortest. - return - } - - // d = mant << (exp - mantbits) - // Next highest floating point number is mant+1 << exp-mantbits. - // Our upper bound is halfway between, mant*2+1 << exp-mantbits-1. - upper := new(decimal) - upper.Assign(mant*2 + 1) - upper.Shift(exp - int(flt.mantbits) - 1) - - // d = mant << (exp - mantbits) - // Next lowest floating point number is mant-1 << exp-mantbits, - // unless mant-1 drops the significant bit and exp is not the minimum exp, - // in which case the next lowest is mant*2-1 << exp-mantbits-1. - // Either way, call it mantlo << explo-mantbits. - // Our lower bound is halfway between, mantlo*2+1 << explo-mantbits-1. - var mantlo uint64 - var explo int - if mant > 1<<flt.mantbits || exp == minexp { - mantlo = mant - 1 - explo = exp - } else { - mantlo = mant*2 - 1 - explo = exp - 1 - } - lower := new(decimal) - lower.Assign(mantlo*2 + 1) - lower.Shift(explo - int(flt.mantbits) - 1) - - // The upper and lower bounds are possible outputs only if - // the original mantissa is even, so that IEEE round-to-even - // would round to the original mantissa and not the neighbors. - inclusive := mant%2 == 0 - - // Now we can figure out the minimum number of digits required. - // Walk along until d has distinguished itself from upper and lower. - for i := 0; i < d.nd; i++ { - var l, m, u byte // lower, middle, upper digits - if i < lower.nd { - l = lower.d[i] - } else { - l = '0' - } - m = d.d[i] - if i < upper.nd { - u = upper.d[i] - } else { - u = '0' - } - - // Okay to round down (truncate) if lower has a different digit - // or if lower is inclusive and is exactly the result of rounding down. - okdown := l != m || (inclusive && l == m && i+1 == lower.nd) - - // Okay to round up if upper has a different digit and - // either upper is inclusive or upper is bigger than the result of rounding up. - okup := m != u && (inclusive || m+1 < u || i+1 < upper.nd) - - // If it's okay to do either, then round to the nearest one. - // If it's okay to do only one, do it. - switch { - case okdown && okup: - d.Round(i + 1) - return - case okdown: - d.RoundDown(i + 1) - return - case okup: - d.RoundUp(i + 1) - return - } - } -} - -type decimalSlice struct { - d []byte - nd, dp int - neg bool -} - -// %e: -d.ddddde±dd -func fmtE(dst EncodingBuffer, neg bool, d decimalSlice, prec int, fmt byte) { - // sign - if neg { - dst.WriteByte('-') - } - - // first digit - ch := byte('0') - if d.nd != 0 { - ch = d.d[0] - } - dst.WriteByte(ch) - - // .moredigits - if prec > 0 { - dst.WriteByte('.') - i := 1 - m := min(d.nd, prec+1) - if i < m { - dst.Write(d.d[i:m]) - i = m - } - for i <= prec { - dst.WriteByte('0') - i++ - } - } - - // e± - dst.WriteByte(fmt) - exp := d.dp - 1 - if d.nd == 0 { // special case: 0 has exponent 0 - exp = 0 - } - if exp < 0 { - ch = '-' - exp = -exp - } else { - ch = '+' - } - dst.WriteByte(ch) - - // dd or ddd - switch { - case exp < 10: - dst.WriteByte('0') - dst.WriteByte(byte(exp) + '0') - case exp < 100: - dst.WriteByte(byte(exp/10) + '0') - dst.WriteByte(byte(exp%10) + '0') - default: - dst.WriteByte(byte(exp/100) + '0') - dst.WriteByte(byte(exp/10)%10 + '0') - dst.WriteByte(byte(exp%10) + '0') - } - - return -} - -// %f: -ddddddd.ddddd -func fmtF(dst EncodingBuffer, neg bool, d decimalSlice, prec int) { - // sign - if neg { - dst.WriteByte('-') - } - - // integer, padded with zeros as needed. - if d.dp > 0 { - m := min(d.nd, d.dp) - dst.Write(d.d[:m]) - for ; m < d.dp; m++ { - dst.WriteByte('0') - } - } else { - dst.WriteByte('0') - } - - // fraction - if prec > 0 { - dst.WriteByte('.') - for i := 0; i < prec; i++ { - ch := byte('0') - if j := d.dp + i; 0 <= j && j < d.nd { - ch = d.d[j] - } - dst.WriteByte(ch) - } - } - - return -} - -// %b: -ddddddddp±ddd -func fmtB(dst EncodingBuffer, neg bool, mant uint64, exp int, flt *floatInfo) { - // sign - if neg { - dst.WriteByte('-') - } - - // mantissa - formatBits(dst, mant, 10, false) - - // p - dst.WriteByte('p') - - // ±exponent - exp -= int(flt.mantbits) - if exp >= 0 { - dst.WriteByte('+') - } - formatBits(dst, uint64(exp), 10, exp < 0) - - return -} - -func min(a, b int) int { - if a < b { - return a - } - return b -} - -func max(a, b int) int { - if a > b { - return a - } - return b -} - -// formatBits computes the string representation of u in the given base. -// If neg is set, u is treated as negative int64 value. -func formatBits(dst EncodingBuffer, u uint64, base int, neg bool) { - if base < 2 || base > len(digits) { - panic("strconv: illegal AppendInt/FormatInt base") - } - // 2 <= base && base <= len(digits) - - var a [64 + 1]byte // +1 for sign of 64bit value in base 2 - i := len(a) - - if neg { - u = -u - } - - // convert bits - if base == 10 { - // common case: use constants for / because - // the compiler can optimize it into a multiply+shift - - if ^uintptr(0)>>32 == 0 { - for u > uint64(^uintptr(0)) { - q := u / 1e9 - us := uintptr(u - q*1e9) // us % 1e9 fits into a uintptr - for j := 9; j > 0; j-- { - i-- - qs := us / 10 - a[i] = byte(us - qs*10 + '0') - us = qs - } - u = q - } - } - - // u guaranteed to fit into a uintptr - us := uintptr(u) - for us >= 10 { - i-- - q := us / 10 - a[i] = byte(us - q*10 + '0') - us = q - } - // u < 10 - i-- - a[i] = byte(us + '0') - - } else if s := shifts[base]; s > 0 { - // base is power of 2: use shifts and masks instead of / and % - b := uint64(base) - m := uintptr(b) - 1 // == 1<<s - 1 - for u >= b { - i-- - a[i] = digits[uintptr(u)&m] - u >>= s - } - // u < base - i-- - a[i] = digits[uintptr(u)] - - } else { - // general case - b := uint64(base) - for u >= b { - i-- - q := u / b - a[i] = digits[uintptr(u-q*b)] - u = q - } - // u < base - i-- - a[i] = digits[uintptr(u)] - } - - // add sign, if any - if neg { - i-- - a[i] = '-' - } - - dst.Write(a[i:]) -} |