add SDL_bsearch

src/stdlib/SDL_qsort.c

@@ -534,5 +534,38 @@ extern void qsortG(void *base, size_t nmemb, size_t size,
 
 #endif /* HAVE_QSORT */
 
+void *
+SDL_bsearch(const void *key, const void *base, size_t nmemb, size_t size, int (*compare)(const void *, const void *))
+{
+#if defined(HAVE_BSEARCH)
+    return bsearch(key, base, nmemb, size, compare);
+#else
+/* SDL's replacement:  Taken from the Public Domain C Library (PDCLib):
+   Permission is granted to use, modify, and / or redistribute at will.
+*/
+    const void *pivot;
+    size_t corr;
+    int rc;
+
+    while (nmemb) {
+        /* algorithm needs -1 correction if remaining elements are an even number. */
+        corr = nmemb % 2;
+        nmemb /= 2;
+        pivot = (const char *)base + (nmemb * size);
+        rc = compare(key, pivot);
+
+        if (rc > 0) {
+            base = (const char *)pivot + size;
+            /* applying correction */
+            nmemb -= (1 - corr);
+        } else if (rc == 0) {
+            return (void *)pivot;
+        }
+    }
+
+    return NULL;
+#endif /* HAVE_BSEARCH */
+}
+
 /* vi: set ts=4 sw=4 expandtab: */