src

Go monorepo.
git clone git://code.dwrz.net/src
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rand.go (726B)

      1 package rand
      2 
      3 import (
      4 	"crypto/rand"
      5 	"fmt"
      6 	"io"
      7 	"math/big"
      8 )
      9 
     10 func init() {
     11 	Reader = rand.Reader
     12 }
     13 
     14 // Reader provides a random reader that can reset during testing.
     15 var Reader io.Reader
     16 
     17 var floatMaxBigInt = big.NewInt(1 << 53)
     18 
     19 // Float64 returns a float64 read from an io.Reader source. The returned float will be between [0.0, 1.0).
     20 func Float64(reader io.Reader) (float64, error) {
     21 	bi, err := rand.Int(reader, floatMaxBigInt)
     22 	if err != nil {
     23 		return 0, fmt.Errorf("failed to read random value, %v", err)
     24 	}
     25 
     26 	return float64(bi.Int64()) / (1 << 53), nil
     27 }
     28 
     29 // CryptoRandFloat64 returns a random float64 obtained from the crypto rand
     30 // source.
     31 func CryptoRandFloat64() (float64, error) {
     32 	return Float64(Reader)
     33 }