diff options
author | Alejandro Colomar <alx@kernel.org> | 2022-12-17 19:29:30 +0100 |
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committer | Alejandro Colomar <alx@kernel.org> | 2023-01-16 21:50:30 +0100 |
commit | a38c6af515af6ac45b5ce32a2313060d68297fea (patch) | |
tree | 4f7866ca19bce1831ab71b5d7b6e9d8fb9a5ed1c /include/c/rand/csrand/csrand_uniform.h | |
parent | eba7ba35ceb4be1f4febc0d2359f0c446fdba718 (diff) |
Signed-off-by: Alejandro Colomar <alx@kernel.org>
Diffstat (limited to 'include/c/rand/csrand/csrand_uniform.h')
-rw-r--r-- | include/c/rand/csrand/csrand_uniform.h | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/include/c/rand/csrand/csrand_uniform.h b/include/c/rand/csrand/csrand_uniform.h new file mode 100644 index 0000000..968ac9f --- /dev/null +++ b/include/c/rand/csrand/csrand_uniform.h @@ -0,0 +1,45 @@ +// Copyright 2023 Alejandro Colomar <alx@kernel.org> +// SPDX-License-Identifier: LGPL-3.0-or-later WITH LGPL-3.0-linking-exception + + +#ifndef INCLUDE_C_RAND_CSRAND_CSRAND_UNIFORM_H_ +#define INCLUDE_C_RAND_CSRAND_CSRAND_UNIFORM_H_ + + +#include <stdint.h> + +#include <c/bit/ceil.h> +#include <c/rand/csrand/csrand.h> + + +#pragma clang assume_nonnull begin +inline uint64_t c_csrand64_uniform(uint64_t n); +inline uint64_t c_csrand64_interval(uint64_t min, uint64_t max); + + +inline uint64_t +c_csrand64_uniform(uint64_t n) +{ + uint64_t r, max, mask; + + max = n - 1; + mask = c_bit_ceil_wrap_64(n) - 1; + + do { + r = c_csrand64(); + r &= mask; + } while (r > max); + + return r; +} + + +inline uint64_t +c_csrand64_interval(uint64_t min, uint64_t max) +{ + return c_csrand64_uniform(max - min + 1) + min; +} +#pragma clang assume_nonnull end + + +#endif // Header guard |