1package rand
 2
 3import (
 4	"crypto/rand"
 5	"fmt"
 6	"io"
 7	"math/big"
 8)
 9
10func init() {
11	Reader = rand.Reader
12}
13
14// Reader provides a random reader that can reset during testing.
15var Reader io.Reader
16
17var 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).
20func 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.
31func CryptoRandFloat64() (float64, error) {
32	return Float64(Reader)
33}