mirror of
https://github.com/wader/fq.git
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109 lines
2.4 KiB
Go
109 lines
2.4 KiB
Go
package mathx
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import (
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"fmt"
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"math"
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"math/big"
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"strconv"
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"strings"
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"github.com/wader/fq/pkg/ranges"
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"golang.org/x/exp/constraints"
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)
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var BasePrefixMap = map[int]string{
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2: "0b",
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8: "0o",
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16: "0x",
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}
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func DigitsInBase[T constraints.Integer](n T, basePrefix bool, base int) int {
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prefixLen := 0
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if basePrefix {
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prefixLen = len(BasePrefixMap[base])
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}
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if n == 0 {
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return prefixLen + 1
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}
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return prefixLen + int(1+math.Floor(math.Log(float64(n))/math.Log(float64(base))))
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}
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func padFormatNumber(s string, base int, basePrefix bool, width int) string {
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prefixStr := ""
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if basePrefix {
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prefixStr = BasePrefixMap[base]
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}
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padStr := ""
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padN := width - len(s) - len(prefixStr)
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if padN > 0 {
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// TODO: something faster?
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padStr = strings.Repeat("0", padN)
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}
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return prefixStr + padStr + s
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}
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func PadFormatInt[T constraints.Signed](i T, base int, basePrefix bool, width int) string {
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return padFormatNumber(strconv.FormatInt(int64(i), base), base, basePrefix, width)
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}
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func PadFormatUint[T constraints.Unsigned](i T, base int, basePrefix bool, width int) string {
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return padFormatNumber(strconv.FormatUint(uint64(i), base), base, basePrefix, width)
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}
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func PadFormatBigInt(i *big.Int, base int, basePrefix bool, width int) string {
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return padFormatNumber(i.Text(base), base, basePrefix, width)
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}
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func Max[T constraints.Ordered](v T, vs ...T) T {
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m := v
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for _, v := range vs {
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if v > m {
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m = v
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}
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}
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return m
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}
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func Min[T constraints.Ordered](v T, vs ...T) T {
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m := v
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for _, v := range vs {
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if v < m {
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m = v
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}
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}
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return m
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}
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func Clamp[T constraints.Ordered](min, max, v T) T {
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return Max(min, Min(max, v))
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}
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type Bits uint64
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func (b Bits) StringByteBits(base int) string {
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if b&0x7 != 0 {
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return BasePrefixMap[base] + strconv.FormatUint(uint64(b)>>3, base) + "." + strconv.FormatUint(uint64(b)&0x7, base)
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}
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return BasePrefixMap[base] + strconv.FormatUint(uint64(b>>3), base)
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}
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type BitRange ranges.Range
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func (r BitRange) StringByteBits(base int) string {
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return fmt.Sprintf("%s-%s", Bits(r.Start).StringByteBits(base), Bits(r.Start+r.Len).StringByteBits(base))
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}
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func TwosComplement(nBits int, n uint64) int64 {
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if n&(1<<(nBits-1)) > 0 {
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// two's complement
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return -int64((^n & ((1 << nBits) - 1)) + 1)
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}
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return int64(n)
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}
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// decode zigzag encoded integer
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// https://developers.google.com/protocol-buffers/docs/encoding
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func ZigZag[U constraints.Unsigned, S constraints.Signed](n U) S {
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return S(n>>1 ^ -(n & 1))
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}
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