Get rid of random_shuffle().

This should hopefully make games from the same seed proceed the same on all
architectures[1], as I can't think of anything else that behaves differently
based on pointer size, endianness or exact pointer values.

I used a NIH implementation instead of passing a third argument to
random_shuffle, as the interface is so much nicer.

[1]. This will be affected by terminal size (elemental colours are not
resolved outside the screen), tile windows size (random animations),
tiles/non-tiles and possibly others.

Also, I don't think we use STL hashes anywhere, but if we'd do, the STL
implementation will matter.  Please don't make this stop you: this commit
is only to make test cases from my stress tests portable which is a small
benefit, perhaps even smaller than the nicer call interface.

1 files changed, 19 insertions, 0 deletions

diff --git a/crawl-ref/source/random.h b/crawl-ref/source/random.h
index 374b89b8f3..476a87b6f6 100644
--- a/crawl-ref/source/random.h
+++ b/crawl-ref/source/random.h
@@ -99,6 +99,25 @@ struct dice_def
 dice_def calc_dice(int num_dice, int max_damage);
 void scale_dice(dice_def &dice, int threshold = 24);
 
+template <typename T>
+void shuffle_array(T* arr, int n)
+{
+    while (n > 1)
+    {
+        int i = random2(n);
+        n--;
+        T tmp = arr[i];
+        arr[i] = arr[n];
+        arr[n] = tmp;
+    }
+}
+
+template <typename T>
+void shuffle_array(vector<T> &vec)
+{
+    shuffle_array(&vec[0], vec.size());
+}
+
 class rng_save_excursion
 {
 public: