95 lines
2.5 KiB
C
95 lines
2.5 KiB
C
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#ifndef __INC_LIB8TION_RANDOM_H
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#define __INC_LIB8TION_RANDOM_H
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///@ingroup lib8tion
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///@defgroup Random Fast random number generators
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/// Fast 8- and 16- bit unsigned random numbers.
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/// Significantly faster than Arduino random(), but
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/// also somewhat less random. You can add entropy.
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///@{
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// X(n+1) = (2053 * X(n)) + 13849)
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#define FASTLED_RAND16_2053 ((uint16_t)(2053))
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#define FASTLED_RAND16_13849 ((uint16_t)(13849))
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/// random number seed
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extern uint16_t rand16seed;// = RAND16_SEED;
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/// Generate an 8-bit random number
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LIB8STATIC uint8_t random8(void)
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{
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rand16seed = (rand16seed * FASTLED_RAND16_2053) + FASTLED_RAND16_13849;
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// return the sum of the high and low bytes, for better
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// mixing and non-sequential correlation
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return (uint8_t)(((uint8_t)(rand16seed & 0xFF)) +
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((uint8_t)(rand16seed >> 8)));
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}
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/// Generate a 16 bit random number
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LIB8STATIC uint16_t random16(void)
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{
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rand16seed = (rand16seed * FASTLED_RAND16_2053) + FASTLED_RAND16_13849;
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return rand16seed;
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}
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/// Generate an 8-bit random number between 0 and lim
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/// @param lim the upper bound for the result
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LIB8STATIC uint8_t random8_max(uint8_t lim)
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{
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uint8_t r = random8();
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r = (r*lim) >> 8;
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return r;
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}
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/// Generate an 8-bit random number in the given range
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/// @param min the lower bound for the random number
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/// @param lim the upper bound for the random number
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LIB8STATIC uint8_t random8_min_max(uint8_t min, uint8_t lim)
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{
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uint8_t delta = lim - min;
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uint8_t r = random8_max(delta) + min;
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return r;
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}
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/// Generate an 16-bit random number between 0 and lim
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/// @param lim the upper bound for the result
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LIB8STATIC uint16_t random16_max(uint16_t lim)
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{
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uint16_t r = random16();
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uint32_t p = (uint32_t)lim * (uint32_t)r;
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r = p >> 16;
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return r;
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}
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/// Generate an 16-bit random number in the given range
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/// @param min the lower bound for the random number
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/// @param lim the upper bound for the random number
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LIB8STATIC uint16_t random16_min_max( uint16_t min, uint16_t lim)
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{
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uint16_t delta = lim - min;
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uint16_t r = random16_max(delta) + min;
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return r;
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}
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/// Set the 16-bit seed used for the random number generator
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LIB8STATIC void random16_set_seed(uint16_t seed)
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{
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rand16seed = seed;
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}
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/// Get the current seed value for the random number generator
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LIB8STATIC uint16_t random16_get_seed(void)
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{
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return rand16seed;
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}
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/// Add entropy into the random number generator
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LIB8STATIC void random16_add_entropy(uint16_t entropy)
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{
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rand16seed += entropy;
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}
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///@}
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#endif
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