1 files changed, 94 insertions, 0 deletions
diff --git a/c_src/raid/helper.c b/c_src/raid/helper.c
new file mode 100644
index 00000000..f66093fa
--- /dev/null
+++ b/c_src/raid/helper.c
@@ -0,0 +1,94 @@
+/*
+ * Copyright (C) 2013 Andrea Mazzoleni
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include "internal.h"
+
+#define RAID_SWAP(a, b) \
+	do { \
+		if (v[a] > v[b]) { \
+			int t = v[a]; \
+			v[a] = v[b]; \
+			v[b] = t; \
+		} \
+	} while (0)
+
+void raid_sort(int n, int *v)
+{
+	/* sorting networks generated with Batcher's Merge-Exchange */
+	switch (n) {
+	case 2:
+		RAID_SWAP(0, 1);
+		break;
+	case 3:
+		RAID_SWAP(0, 2);
+		RAID_SWAP(0, 1);
+		RAID_SWAP(1, 2);
+		break;
+	case 4:
+		RAID_SWAP(0, 2);
+		RAID_SWAP(1, 3);
+		RAID_SWAP(0, 1);
+		RAID_SWAP(2, 3);
+		RAID_SWAP(1, 2);
+		break;
+	case 5:
+		RAID_SWAP(0, 4);
+		RAID_SWAP(0, 2);
+		RAID_SWAP(1, 3);
+		RAID_SWAP(2, 4);
+		RAID_SWAP(0, 1);
+		RAID_SWAP(2, 3);
+		RAID_SWAP(1, 4);
+		RAID_SWAP(1, 2);
+		RAID_SWAP(3, 4);
+		break;
+	case 6:
+		RAID_SWAP(0, 4);
+		RAID_SWAP(1, 5);
+		RAID_SWAP(0, 2);
+		RAID_SWAP(1, 3);
+		RAID_SWAP(2, 4);
+		RAID_SWAP(3, 5);
+		RAID_SWAP(0, 1);
+		RAID_SWAP(2, 3);
+		RAID_SWAP(4, 5);
+		RAID_SWAP(1, 4);
+		RAID_SWAP(1, 2);
+		RAID_SWAP(3, 4);
+		break;
+	}
+}
+
+void raid_insert(int n, int *v, int i)
+{
+	/* we don't use binary search because this is intended */
+	/* for very small vectors and we want to optimize the case */
+	/* of elements inserted already in order */
+
+	/* insert at the end */
+	v[n] = i;
+
+	/* swap until in the correct position */
+	while (n > 0 && v[n - 1] > v[n]) {
+		/* swap */
+		int t = v[n - 1];
+
+		v[n - 1] = v[n];
+		v[n] = t;
+
+		/* previous position */
+		--n;
+	}
+}
+