unbiasedModulo32 uniformly modulos v by n over a sufficiently large data set, regenerating v if necessary. n must be > 0. All input bits in v must be fully random, you cannot cast a random uint8/uint16 for input into this function. See more details on this algorithm here: https://lemire.me/blog/201
(v uint32, n int32)
| 42 | // See more details on this algorithm here: |
| 43 | // https://lemire.me/blog/2016/06/27/a-fast-alternative-to-the-modulo-reduction/ |
| 44 | func unbiasedModulo32(v uint32, n int32) (int32, error) { |
| 45 | // #nosec G115 - These conversions are safe within the context of this algorithm |
| 46 | // The conversions here are part of an unbiased modulo algorithm for random number generation |
| 47 | // where the values are properly handled within their respective ranges. |
| 48 | prod := uint64(v) * uint64(n) |
| 49 | // #nosec G115 - Safe conversion as part of the unbiased modulo algorithm |
| 50 | low := uint32(prod) |
| 51 | // #nosec G115 - Safe conversion as part of the unbiased modulo algorithm |
| 52 | if low < uint32(n) { |
| 53 | // #nosec G115 - Safe conversion as part of the unbiased modulo algorithm |
| 54 | thresh := uint32(-n) % uint32(n) |
| 55 | for low < thresh { |
| 56 | err := binary.Read(rand.Reader, binary.BigEndian, &v) |
| 57 | if err != nil { |
| 58 | return 0, err |
| 59 | } |
| 60 | // #nosec G115 - Safe conversion as part of the unbiased modulo algorithm |
| 61 | prod = uint64(v) * uint64(n) |
| 62 | // #nosec G115 - Safe conversion as part of the unbiased modulo algorithm |
| 63 | low = uint32(prod) |
| 64 | } |
| 65 | } |
| 66 | // #nosec G115 - Safe conversion as part of the unbiased modulo algorithm |
| 67 | return int32(prod >> 32), nil |
| 68 | } |
| 69 | |
| 70 | // StringCharset generates a random string using the provided charset and size. |
| 71 | func StringCharset(charSetStr string, size int) (string, error) { |