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mirror of https://github.com/wader/fq.git synced 2024-11-24 03:05:22 +03:00
fq/internal/num/num.go
2021-09-12 13:08:50 +02:00

132 lines
2.5 KiB
Go

package num
import (
"fmt"
"math"
"strconv"
"strings"
"github.com/wader/fq/pkg/ranges"
)
var BasePrefixMap = map[int]string{
2: "0b",
8: "0o",
16: "0x",
}
func DigitsInBase(n int64, basePrefix bool, base int) int {
prefixLen := 0
if basePrefix {
prefixLen = len(BasePrefixMap[base])
}
if n == 0 {
return prefixLen + 1
}
return prefixLen + int(1+math.Floor(math.Log(float64(n))/math.Log(float64(base))))
}
func padFormatNumber(s string, base int, basePrefix bool, width int) string {
prefixStr := ""
if basePrefix {
prefixStr = BasePrefixMap[base]
}
padStr := ""
padN := width - len(s) - len(prefixStr)
if padN > 0 {
// TODO: something faster?
padStr = strings.Repeat("0", padN)
}
return prefixStr + padStr + s
}
func PadFormatInt(i int64, base int, basePrefix bool, width int) string {
return padFormatNumber(strconv.FormatInt(i, base), base, basePrefix, width)
}
func PadFormatUint(i uint64, base int, basePrefix bool, width int) string {
return padFormatNumber(strconv.FormatUint(i, base), base, basePrefix, width)
}
func MaxUInt64(a, b uint64) uint64 {
if a < b {
return b
}
return a
}
func MinUInt64(a, b uint64) uint64 {
if a > b {
return b
}
return a
}
func MaxInt64(a, b int64) int64 {
if a < b {
return b
}
return a
}
func MinInt64(a, b int64) int64 {
if a > b {
return b
}
return a
}
func MaxInt(a, b int) int {
if a < b {
return b
}
return a
}
func MinInt(a, b int) int {
if a > b {
return b
}
return a
}
func ClampInt(min, max, v int) int {
return MaxInt(min, MinInt(max, v))
}
func ClampInt64(min, max, v int64) int64 {
return MaxInt64(min, MinInt64(max, v))
}
type Bits uint64
func (b Bits) StringByteBits(base int) string {
if b&0x7 != 0 {
return BasePrefixMap[base] + strconv.FormatUint(uint64(b)>>3, base) + "." + strconv.FormatUint(uint64(b)&0x7, base)
}
return BasePrefixMap[base] + strconv.FormatUint(uint64(b>>3), base)
}
type BitRange ranges.Range
func (r BitRange) StringByteBits(base int) string {
if r.Len == 0 {
return fmt.Sprintf("%s-NA", Bits(r.Start).StringByteBits(base))
}
return fmt.Sprintf("%s-%s", Bits(r.Start).StringByteBits(base), Bits(r.Start+r.Len-1).StringByteBits(base))
}
func TwosComplement(nBits int, n uint64) int64 {
if n&(1<<(nBits-1)) > 0 {
// two's complement
return -int64((^n & ((1 << nBits) - 1)) + 1)
}
return int64(n)
}
// decode zigzag encoded integer
// https://developers.google.com/protocol-buffers/docs/encoding
func ZigZag(n uint64) int64 {
return int64(n>>1 ^ -(n & 1))
}