Fix compilation on kernels prior to Linux 2.6.11

Copy Linux implementation of sort() into ieee80211_scan_ap.c


git-svn-id: http://madwifi-project.org/svn/madwifi/trunk@3407 0192ed92-7a03-0410-a25b-9323aeb14dbd

net80211/ieee80211_scan_ap.c

@@ -1,5 +1,6 @@
 /*-
  * Copyright (c) 2002-2005 Sam Leffler, Errno Consulting
+ * Copyright (c) 2005  Matt Mackall <mpm@selenic.com>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -48,7 +49,77 @@
 #include <linux/delay.h>
 
 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,11)
-#include "sort.c"
+/* Copied from Linux lib/sort.c */
+static void u32_swap(void *a, void *b, int size)
+{
+	u32 t = *(u32 *)a;
+	*(u32 *)a = *(u32 *)b;
+	*(u32 *)b = t;
+}
+
+static void generic_swap(void *a, void *b, int size)
+{
+	char t;
+
+	do {
+		t = *(char *)a;
+		*(char *)a++ = *(char *)b;
+		*(char *)b++ = t;
+	} while (--size > 0);
+}
+
+/**
+ * sort - sort an array of elements
+ * @base: pointer to data to sort
+ * @num: number of elements
+ * @size: size of each element
+ * @cmp: pointer to comparison function
+ * @swap: pointer to swap function or NULL
+ *
+ * This function does a heapsort on the given array. You may provide a
+ * swap function optimized to your element type.
+ *
+ * Sorting time is O(n log n) both on average and worst-case. While
+ * qsort is about 20% faster on average, it suffers from exploitable
+ * O(n*n) worst-case behavior and extra memory requirements that make
+ * it less suitable for kernel use.
+ */
+
+void sort(void *base, size_t num, size_t size,
+	  int (*cmp)(const void *, const void *),
+	  void (*swap)(void *, void *, int size))
+{
+	/* pre-scale counters for performance */
+	int i = (num/2 - 1) * size, n = num * size, c, r;
+
+	if (!swap)
+		swap = (size == 4 ? u32_swap : generic_swap);
+
+	/* heapify */
+	for ( ; i >= 0; i -= size) {
+		for (r = i; r * 2 + size < n; r  = c) {
+			c = r * 2 + size;
+			if (c < n - size && cmp(base + c, base + c + size) < 0)
+				c += size;
+			if (cmp(base + r, base + c) >= 0)
+				break;
+			swap(base + r, base + c, size);
+		}
+	}
+
+	/* sort */
+	for (i = n - size; i > 0; i -= size) {
+		swap(base, base + i, size);
+		for (r = 0; r * 2 + size < i; r = c) {
+			c = r * 2 + size;
+			if (c < i - size && cmp(base + c, base + c + size) < 0)
+				c += size;
+			if (cmp(base + r, base + c) >= 0)
+				break;
+			swap(base + r, base + c, size);
+		}
+	}
+}
 #else
 #include <linux/sort.h>
 #endif