Jemalloc updated to 3.0.0.

[redis.git] / deps / jemalloc.orig / include / jemalloc / internal / prn.h

diff --git a/deps/jemalloc.orig/include/jemalloc/internal/prn.h b/deps/jemalloc.orig/include/jemalloc/internal/prn.h
new file mode 100644 (file)
index 0000000..0709d70
--- /dev/null
+++ b/deps/jemalloc.orig/include/jemalloc/internal/prn.h
@@ -0,0 +1,60 @@
+/******************************************************************************/
+#ifdef JEMALLOC_H_TYPES
+
+/*
+ * Simple linear congruential pseudo-random number generator:
+ *
+ *   prn(y) = (a*x + c) % m
+ *
+ * where the following constants ensure maximal period:
+ *
+ *   a == Odd number (relatively prime to 2^n), and (a-1) is a multiple of 4.
+ *   c == Odd number (relatively prime to 2^n).
+ *   m == 2^32
+ *
+ * See Knuth's TAOCP 3rd Ed., Vol. 2, pg. 17 for details on these constraints.
+ *
+ * This choice of m has the disadvantage that the quality of the bits is
+ * proportional to bit position.  For example. the lowest bit has a cycle of 2,
+ * the next has a cycle of 4, etc.  For this reason, we prefer to use the upper
+ * bits.
+ *
+ * Macro parameters:
+ *   uint32_t r          : Result.
+ *   unsigned lg_range   : (0..32], number of least significant bits to return.
+ *   uint32_t state      : Seed value.
+ *   const uint32_t a, c : See above discussion.
+ */
+#define prn32(r, lg_range, state, a, c) do {                           \
+       assert(lg_range > 0);                                           \
+       assert(lg_range <= 32);                                         \
+                                                                       \
+       r = (state * (a)) + (c);                                        \
+       state = r;                                                      \
+       r >>= (32 - lg_range);                                          \
+} while (false)
+
+/* Same as prn32(), but 64 bits of pseudo-randomness, using uint64_t. */
+#define prn64(r, lg_range, state, a, c) do {                           \
+       assert(lg_range > 0);                                           \
+       assert(lg_range <= 64);                                         \
+                                                                       \
+       r = (state * (a)) + (c);                                        \
+       state = r;                                                      \
+       r >>= (64 - lg_range);                                          \
+} while (false)
+
+#endif /* JEMALLOC_H_TYPES */
+/******************************************************************************/
+#ifdef JEMALLOC_H_STRUCTS
+
+#endif /* JEMALLOC_H_STRUCTS */
+/******************************************************************************/
+#ifdef JEMALLOC_H_EXTERNS
+
+#endif /* JEMALLOC_H_EXTERNS */
+/******************************************************************************/
+#ifdef JEMALLOC_H_INLINES
+
+#endif /* JEMALLOC_H_INLINES */
+/******************************************************************************/