From 2d276366440af245004806e217301bf2446c1a90 Mon Sep 17 00:00:00 2001
From: chme <christian.meffert@googlemail.com>
Date: Sat, 15 Oct 2016 10:06:18 +0200
Subject: [PATCH] [rng] Add function to shuffle an int array

---
 src/rng.c | 19 +++++++++++++++++++
 src/rng.h |  3 +++
 2 files changed, 22 insertions(+)

diff --git a/src/rng.c b/src/rng.c
index 5b57e06a..d36b13b3 100644
--- a/src/rng.c
+++ b/src/rng.c
@@ -144,3 +144,22 @@ shuffle_ptr(struct rng_ctx *ctx, void **values, int len)
     }
 }
 
+/* Fisher-Yates shuffling algorithm
+ * Durstenfeld in-place shuffling variant
+ */
+void
+shuffle_int(struct rng_ctx *ctx, int *values, int len)
+{
+  int i;
+  int32_t j;
+  int tmp;
+
+  for (i = len - 1; i > 0; i--)
+    {
+      j = rng_rand_range(ctx, 0, i + 1);
+
+      tmp = values[i];
+      values[i] = values[j];
+      values[j] = tmp;
+    }
+}
diff --git a/src/rng.h b/src/rng.h
index b6a2c34f..12d980c8 100644
--- a/src/rng.h
+++ b/src/rng.h
@@ -21,5 +21,8 @@ rng_rand_range(struct rng_ctx *ctx, int32_t min, int32_t max);
 void
 shuffle_ptr(struct rng_ctx *ctx, void **values, int len);
 
+void
+shuffle_int(struct rng_ctx *ctx, int *values, int len);
+
 #endif /* !__RNG_H__ */