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libraries/FastLED/src/lib8tion/random8.h

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+#pragma once
+
+#ifndef __INC_LIB8TION_RANDOM_H
+#define __INC_LIB8TION_RANDOM_H
+
+#include "fl/stdint.h"
+
+#include "lib8tion/lib8static.h"
+
+/// @file random8.h
+/// Fast, efficient random number generators specifically
+/// designed for high-performance LED programming.
+
+/// @ingroup lib8tion
+/// @{
+
+/// @defgroup Random Fast Random Number Generators
+/// Fast 8-bit and 16-bit unsigned random number generators.
+/// Significantly faster than Arduino random(), but
+/// also somewhat less random.  You can add entropy.
+///
+/// Pseudo-random number generation follows the form:
+///   @code
+///   X(n+1) = (2053 * X(n)) + 13849)
+///   @endcode
+/// @{
+
+/// Multiplier value for pseudo-random number generation
+#define FASTLED_RAND16_2053 ((uint16_t)(2053))
+/// Increment value for pseudo-random number generation
+#define FASTLED_RAND16_13849 ((uint16_t)(13849))
+
+#if defined(LIB8_ATTINY)
+/// Multiplies a value by the pseudo-random multiplier
+#define APPLY_FASTLED_RAND16_2053(x) (x << 11) + (x << 2) + x
+#else
+/// Multiplies a value by the pseudo-random multiplier
+#define APPLY_FASTLED_RAND16_2053(x) (x * FASTLED_RAND16_2053)
+#endif
+
+/// Seed for the random number generator functions
+extern uint16_t rand16seed; // = RAND16_SEED;
+
+/// Generate an 8-bit random number
+/// @returns random 8-bit number, in the range 0-255
+LIB8STATIC uint8_t random8() {
+    rand16seed = APPLY_FASTLED_RAND16_2053(rand16seed) + FASTLED_RAND16_13849;
+    // return the sum of the high and low bytes, for better
+    //  mixing and non-sequential correlation
+    return (uint8_t)(((uint8_t)(rand16seed & 0xFF)) +
+                     ((uint8_t)(rand16seed >> 8)));
+}
+
+/// Generate a 16-bit random number
+/// @returns random 16-bit number, in the range 0-65535
+LIB8STATIC uint16_t random16() {
+    rand16seed = APPLY_FASTLED_RAND16_2053(rand16seed) + FASTLED_RAND16_13849;
+    return rand16seed;
+}
+
+/// Generate an 8-bit random number between 0 and lim
+/// @param lim the upper bound for the result, exclusive
+LIB8STATIC uint8_t random8(uint8_t lim) {
+    uint8_t r = random8();
+    r = (r * lim) >> 8;
+    return r;
+}
+
+/// Generate an 8-bit random number in the given range
+/// @param min the lower bound for the random number, inclusive
+/// @param lim the upper bound for the random number, exclusive
+LIB8STATIC uint8_t random8(uint8_t min, uint8_t lim) {
+    uint8_t delta = lim - min;
+    uint8_t r = random8(delta) + min;
+    return r;
+}
+
+/// Generate an 16-bit random number between 0 and lim
+/// @param lim the upper bound for the result, exclusive
+LIB8STATIC uint16_t random16(uint16_t lim) {
+    uint16_t r = random16();
+    uint32_t p = (uint32_t)lim * (uint32_t)r;
+    r = p >> 16;
+    return r;
+}
+
+/// Generate an 16-bit random number in the given range
+/// @param min the lower bound for the random number, inclusive
+/// @param lim the upper bound for the random number, exclusive
+LIB8STATIC uint16_t random16(uint16_t min, uint16_t lim) {
+    uint16_t delta = lim - min;
+    uint16_t r = random16(delta) + min;
+    return r;
+}
+
+/// Set the 16-bit seed used for the random number generator
+LIB8STATIC void random16_set_seed(uint16_t seed) { rand16seed = seed; }
+
+/// Get the current seed value for the random number generator
+LIB8STATIC uint16_t random16_get_seed() { return rand16seed; }
+
+/// Add entropy into the random number generator
+LIB8STATIC void random16_add_entropy(uint16_t entropy) {
+    rand16seed += entropy;
+}
+
+/// @} Random
+/// @} lib8tion
+
+#endif