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-rw-r--r--thirdparty/misc/pcg.cpp15
1 files changed, 15 insertions, 0 deletions
diff --git a/thirdparty/misc/pcg.cpp b/thirdparty/misc/pcg.cpp
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+++ b/thirdparty/misc/pcg.cpp
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+// *Really* minimal PCG32 code / (c) 2014 M.E. O'Neill / pcg-random.org
+// Licensed under Apache License 2.0 (NO WARRANTY, etc. see website)
+
+#include "pcg.h"
+
+uint32_t pcg32_random_r(pcg32_random_t* rng)
+{
+ uint64_t oldstate = rng->state;
+ // Advance internal state
+ rng->state = oldstate * 6364136223846793005ULL + (rng->inc|1);
+ // Calculate output function (XSH RR), uses old state for max ILP
+ uint32_t xorshifted = ((oldstate >> 18u) ^ oldstate) >> 27u;
+ uint32_t rot = oldstate >> 59u;
+ return (xorshifted >> rot) | (xorshifted << ((-rot) & 31));
+}