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

diff --git a/net80211/ieee80211_scan_ap.c b/net80211/ieee80211_scan_ap.c
index a3f4cf8aa79dec9712d879f022a3b7ad2df5fd4b..a617881499ea8a9fd3702642e23bbd7dcfb89789 100644 (file)
--- a/net80211/ieee80211_scan_ap.c
+++ b/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