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| author | Mark Kriegsman <1334634+kriegsman@users.noreply.github.com> | 2020-02-11 18:19:42 +0300 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2020-02-11 18:19:42 +0300 |
| commit | 1e6e56b49d22778f8a9649633996d01545aef1be (patch) | |
| tree | 1af04905fc1a44b1725dd28befba2da48529f239 | |
| parent | 89e83a930587f5a6bb5a7246f88330958ebbadcc (diff) | |
| parent | 63b254ea0eaabc4aa8926acdb6dd6cac32b98e43 (diff) | |
Merge pull request #916 from grandinquisitor/master
On ATtiny (only) where there is no hardware multiplier, convert use shifts&adds to achieve multiplication by the chosen LCG constant in 'random' function.
| -rw-r--r-- | lib8tion/random8.h | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/lib8tion/random8.h b/lib8tion/random8.h index ba60cf57..d834abd5 100644 --- a/lib8tion/random8.h +++ b/lib8tion/random8.h @@ -12,13 +12,19 @@ #define FASTLED_RAND16_2053 ((uint16_t)(2053)) #define FASTLED_RAND16_13849 ((uint16_t)(13849)) +#if defined(LIB8_ATTINY) +#define APPLY_FASTLED_RAND16_2053(x) (x << 11) + (x << 2) + x +#else +#define APPLY_FASTLED_RAND16_2053(x) (x * FASTLED_RAND16_2053) +#endif + /// 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; + 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)) + @@ -28,7 +34,7 @@ LIB8STATIC uint8_t random8() /// Generate a 16 bit random number LIB8STATIC uint16_t random16() { - rand16seed = (rand16seed * FASTLED_RAND16_2053) + FASTLED_RAND16_13849; + rand16seed = APPLY_FASTLED_RAND16_2053(rand16seed) + FASTLED_RAND16_13849; return rand16seed; } |