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libraries/FastLED-3.2.9/lib8tion/random8.h

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+#ifndef __INC_LIB8TION_RANDOM_H
+#define __INC_LIB8TION_RANDOM_H
+///@ingroup lib8tion
+
+///@defgroup Random Fast random number generators
+/// Fast 8- and 16- bit unsigned random numbers.
+///  Significantly faster than Arduino random(), but
+///  also somewhat less random.  You can add entropy.
+///@{
+
+// X(n+1) = (2053 * X(n)) + 13849)
+#define FASTLED_RAND16_2053  ((uint16_t)(2053))
+#define FASTLED_RAND16_13849 ((uint16_t)(13849))
+
+/// random number seed
+extern uint16_t rand16seed;// = RAND16_SEED;
+
+/// Generate an 8-bit random number
+LIB8STATIC uint8_t random8()
+{
+    rand16seed = (rand16seed * FASTLED_RAND16_2053) + 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
+LIB8STATIC uint16_t random16()
+{
+    rand16seed = (rand16seed * FASTLED_RAND16_2053) + FASTLED_RAND16_13849;
+    return rand16seed;
+}
+
+/// Generate an 8-bit random number between 0 and lim
+/// @param lim the upper bound for the result
+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
+/// @param lim the upper bound for the random number
+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
+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
+/// @param lim the upper bound for the random number
+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;
+}
+
+///@}
+
+#endif