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