Fix qsort

libraries/mlcrt/src/algorithm.c

@@ -1,7 +1,7 @@
 /*
  * algorithm.c
  *
- * Copyright (C) 2017 Aleksandar Andrejevic <theflash@sdf.lonestar.org>
+ * Copyright (C) 2019 Aleksandar Andrejevic <theflash@sdf.lonestar.org>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
@@ -22,26 +22,25 @@
 
 void __CRT_PUBLIC(qsort)(void *base, size_t nmemb, size_t size, int (*compare)(const void*, const void*))
 {
-    void *pivot = (void*)((uintptr_t)base + (nmemb / 2) * size);
-    void *temp = __builtin_alloca(size);
-    if (nmemb <= 1) return;
+    char *bytes = base, pivot[size], temp[size];
+    ptrdiff_t low = 0, high = nmemb - 1;
 
-    size_t low = 0;
-    size_t high = nmemb - 1;
+    if (nmemb <= 1) return;
+    __builtin_memcpy(pivot, &bytes[(nmemb / 2 - 1) * size], size);
 
     for (;;)
     {
-        while (compare((void*)((uintptr_t)base + low * size), pivot) < 0) low++;
-        while (compare((void*)((uintptr_t)base + high * size), pivot) > 0) high--;
+        while (compare(&bytes[low * size], pivot) < 0) low++;
+        while (compare(&bytes[high * size], pivot) > 0) high--;
         if (low >= high) break;
 
-        __builtin_memcpy(temp, (void*)((uintptr_t)base + low * size), size);
-        __builtin_memcpy((void*)((uintptr_t)base + low * size), (void*)((uintptr_t)base + high * size), size);
-        __builtin_memcpy((void*)((uintptr_t)base + high * size), temp, size);
+        __builtin_memcpy(temp, &bytes[low * size], size);
+        __builtin_memcpy(&bytes[low * size], &bytes[high * size], size);
+        __builtin_memcpy(&bytes[high * size], temp, size);
     }
 
-    __CRT_PUBLIC(qsort)(base, high, size, compare);
-    __CRT_PUBLIC(qsort)((void*)((size_t)base + high * size), nmemb - high, size, compare);
+    __CRT_PUBLIC(qsort)(bytes, high + 1, size, compare);
+    __CRT_PUBLIC(qsort)(&bytes[(high + 1) * size], nmemb - (high + 1), size, compare);
 }
 
 void *__CRT_PUBLIC(bsearch)(const void *key, const void *base, size_t nmemb, size_t size, int (*compare)(const void*, const void*))