asearch: Add context pointer to asearch comparison callback

[ccan] / ccan / asearch / asearch.c

diff --git a/ccan/asearch/asearch.c b/ccan/asearch/asearch.c
new file mode 100644 (file)
index 0000000..f189dcd
--- /dev/null
+++ b/ccan/asearch/asearch.c
@@ -0,0 +1,49 @@
+#include <ccan/asearch/asearch.h>
+
+#include <stddef.h>
+
+/* Steal glibc's code. */
+
+/* Perform binary search - inline version.
+   Copyright (C) 1991-2015 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+void *
+_asearch (const void *__key, const void *__base, size_t __nmemb, size_t __size,
+         asearch_cmp __compar, void *ctx)
+{
+  size_t __l, __u, __idx;
+  const void *__p;
+  int __comparison;
+
+  __l = 0;
+  __u = __nmemb;
+  while (__l < __u)
+    {
+      __idx = (__l + __u) / 2;
+      __p = (void *) (((const char *) __base) + (__idx * __size));
+      __comparison = (*__compar) (__key, __p, ctx);
+      if (__comparison < 0)
+        __u = __idx;
+      else if (__comparison > 0)
+        __l = __idx + 1;
+      else
+        return (void *) __p;
+    }
+
+  return NULL;
+}