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Diffstat (limited to 'vendor/k8s.io/apimachinery/pkg/api/resource/math.go')
-rw-r--r-- | vendor/k8s.io/apimachinery/pkg/api/resource/math.go | 314 |
1 files changed, 314 insertions, 0 deletions
diff --git a/vendor/k8s.io/apimachinery/pkg/api/resource/math.go b/vendor/k8s.io/apimachinery/pkg/api/resource/math.go new file mode 100644 index 000000000..72d3880c0 --- /dev/null +++ b/vendor/k8s.io/apimachinery/pkg/api/resource/math.go @@ -0,0 +1,314 @@ +/* +Copyright 2014 The Kubernetes Authors. + +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. +*/ + +package resource + +import ( + "math/big" + + inf "gopkg.in/inf.v0" +) + +const ( + // maxInt64Factors is the highest value that will be checked when removing factors of 10 from an int64. + // It is also the maximum decimal digits that can be represented with an int64. + maxInt64Factors = 18 +) + +var ( + // Commonly needed big.Int values-- treat as read only! + bigTen = big.NewInt(10) + bigZero = big.NewInt(0) + bigOne = big.NewInt(1) + bigThousand = big.NewInt(1000) + big1024 = big.NewInt(1024) + + // Commonly needed inf.Dec values-- treat as read only! + decZero = inf.NewDec(0, 0) + decOne = inf.NewDec(1, 0) + decMinusOne = inf.NewDec(-1, 0) + decThousand = inf.NewDec(1000, 0) + dec1024 = inf.NewDec(1024, 0) + decMinus1024 = inf.NewDec(-1024, 0) + + // Largest (in magnitude) number allowed. + maxAllowed = infDecAmount{inf.NewDec((1<<63)-1, 0)} // == max int64 + + // The maximum value we can represent milli-units for. + // Compare with the return value of Quantity.Value() to + // see if it's safe to use Quantity.MilliValue(). + MaxMilliValue = int64(((1 << 63) - 1) / 1000) +) + +const mostNegative = -(mostPositive + 1) +const mostPositive = 1<<63 - 1 + +// int64Add returns a+b, or false if that would overflow int64. +func int64Add(a, b int64) (int64, bool) { + c := a + b + switch { + case a > 0 && b > 0: + if c < 0 { + return 0, false + } + case a < 0 && b < 0: + if c > 0 { + return 0, false + } + if a == mostNegative && b == mostNegative { + return 0, false + } + } + return c, true +} + +// int64Multiply returns a*b, or false if that would overflow or underflow int64. +func int64Multiply(a, b int64) (int64, bool) { + if a == 0 || b == 0 || a == 1 || b == 1 { + return a * b, true + } + if a == mostNegative || b == mostNegative { + return 0, false + } + c := a * b + return c, c/b == a +} + +// int64MultiplyScale returns a*b, assuming b is greater than one, or false if that would overflow or underflow int64. +// Use when b is known to be greater than one. +func int64MultiplyScale(a int64, b int64) (int64, bool) { + if a == 0 || a == 1 { + return a * b, true + } + if a == mostNegative && b != 1 { + return 0, false + } + c := a * b + return c, c/b == a +} + +// int64MultiplyScale10 multiplies a by 10, or returns false if that would overflow. This method is faster than +// int64Multiply(a, 10) because the compiler can optimize constant factor multiplication. +func int64MultiplyScale10(a int64) (int64, bool) { + if a == 0 || a == 1 { + return a * 10, true + } + if a == mostNegative { + return 0, false + } + c := a * 10 + return c, c/10 == a +} + +// int64MultiplyScale100 multiplies a by 100, or returns false if that would overflow. This method is faster than +// int64Multiply(a, 100) because the compiler can optimize constant factor multiplication. +func int64MultiplyScale100(a int64) (int64, bool) { + if a == 0 || a == 1 { + return a * 100, true + } + if a == mostNegative { + return 0, false + } + c := a * 100 + return c, c/100 == a +} + +// int64MultiplyScale1000 multiplies a by 1000, or returns false if that would overflow. This method is faster than +// int64Multiply(a, 1000) because the compiler can optimize constant factor multiplication. +func int64MultiplyScale1000(a int64) (int64, bool) { + if a == 0 || a == 1 { + return a * 1000, true + } + if a == mostNegative { + return 0, false + } + c := a * 1000 + return c, c/1000 == a +} + +// positiveScaleInt64 multiplies base by 10^scale, returning false if the +// value overflows. Passing a negative scale is undefined. +func positiveScaleInt64(base int64, scale Scale) (int64, bool) { + switch scale { + case 0: + return base, true + case 1: + return int64MultiplyScale10(base) + case 2: + return int64MultiplyScale100(base) + case 3: + return int64MultiplyScale1000(base) + case 6: + return int64MultiplyScale(base, 1000000) + case 9: + return int64MultiplyScale(base, 1000000000) + default: + value := base + var ok bool + for i := Scale(0); i < scale; i++ { + if value, ok = int64MultiplyScale(value, 10); !ok { + return 0, false + } + } + return value, true + } +} + +// negativeScaleInt64 reduces base by the provided scale, rounding up, until the +// value is zero or the scale is reached. Passing a negative scale is undefined. +// The value returned, if not exact, is rounded away from zero. +func negativeScaleInt64(base int64, scale Scale) (result int64, exact bool) { + if scale == 0 { + return base, true + } + + value := base + var fraction bool + for i := Scale(0); i < scale; i++ { + if !fraction && value%10 != 0 { + fraction = true + } + value = value / 10 + if value == 0 { + if fraction { + if base > 0 { + return 1, false + } + return -1, false + } + return 0, true + } + } + if fraction { + if base > 0 { + value += 1 + } else { + value += -1 + } + } + return value, !fraction +} + +func pow10Int64(b int64) int64 { + switch b { + case 0: + return 1 + case 1: + return 10 + case 2: + return 100 + case 3: + return 1000 + case 4: + return 10000 + case 5: + return 100000 + case 6: + return 1000000 + case 7: + return 10000000 + case 8: + return 100000000 + case 9: + return 1000000000 + case 10: + return 10000000000 + case 11: + return 100000000000 + case 12: + return 1000000000000 + case 13: + return 10000000000000 + case 14: + return 100000000000000 + case 15: + return 1000000000000000 + case 16: + return 10000000000000000 + case 17: + return 100000000000000000 + case 18: + return 1000000000000000000 + default: + return 0 + } +} + +// negativeScaleInt64 returns the result of dividing base by scale * 10 and the remainder, or +// false if no such division is possible. Dividing by negative scales is undefined. +func divideByScaleInt64(base int64, scale Scale) (result, remainder int64, exact bool) { + if scale == 0 { + return base, 0, true + } + // the max scale representable in base 10 in an int64 is 18 decimal places + if scale >= 18 { + return 0, base, false + } + divisor := pow10Int64(int64(scale)) + return base / divisor, base % divisor, true +} + +// removeInt64Factors divides in a loop; the return values have the property that +// value == result * base ^ scale +func removeInt64Factors(value int64, base int64) (result int64, times int32) { + times = 0 + result = value + negative := result < 0 + if negative { + result = -result + } + switch base { + // allow the compiler to optimize the common cases + case 10: + for result >= 10 && result%10 == 0 { + times++ + result = result / 10 + } + // allow the compiler to optimize the common cases + case 1024: + for result >= 1024 && result%1024 == 0 { + times++ + result = result / 1024 + } + default: + for result >= base && result%base == 0 { + times++ + result = result / base + } + } + if negative { + result = -result + } + return result, times +} + +// removeBigIntFactors divides in a loop; the return values have the property that +// d == result * factor ^ times +// d may be modified in place. +// If d == 0, then the return values will be (0, 0) +func removeBigIntFactors(d, factor *big.Int) (result *big.Int, times int32) { + q := big.NewInt(0) + m := big.NewInt(0) + for d.Cmp(bigZero) != 0 { + q.DivMod(d, factor, m) + if m.Cmp(bigZero) != 0 { + break + } + times++ + d, q = q, d + } + return d, times +} |