From: Martin Mares <mj@ucw.cz>
Date: Sun, 2 Oct 2005 10:52:23 +0000 (+0000)
Subject: Added a library module for generic binary search.
X-Git-Tag: holmes-import~725
X-Git-Url: http://mj.ucw.cz/gitweb/?a=commitdiff_plain;h=7068cd693f95253661ba9feb219831257b234b75;p=libucw.git

Added a library module for generic binary search.
---

diff --git a/lib/binsearch.h b/lib/binsearch.h
new file mode 100644
index 00000000..67419563
--- /dev/null
+++ b/lib/binsearch.h
@@ -0,0 +1,26 @@
+/*
+ *	UCW Library -- Generic Binary Search
+ *
+ *	(c) 2005 Martin Mares <mj@ucw.cz>
+ *
+ *	This software may be freely distributed and used according to the terms
+ *	of the GNU Lesser General Public License.
+ */
+
+#define BIN_SEARCH_FIRST_GE_CMP(ary,N,x,ary_lt_x)  ({		\
+  uns l = 0, r = (N);						\
+  while (l < r)							\
+    {								\
+      uns m = (l+r)/2;						\
+      if (ary_lt_x(ary,m,x))					\
+	l = m+1;						\
+      else							\
+	r = m;							\
+    }								\
+  l;								\
+})
+
+#define ARY_LT_NUM(ary,i,x) (ary)[i] < (x)
+
+#define BIN_SEARCH_FIRST_GE(ary,N,x) BIN_SEARCH_FIRST_GE_CMP(ary,N,x,ARY_LT_NUM)
+#define BIN_SEARCH_EQ(ary,N,x) ({ int i = BIN_SEARCH_FIRST_GE(ary,N,x); if (i >= (N) || (ary)[i] != (x)) i=-1; i; })