Added bsearch

diff --git a/lang/cem/libcc/gen/LIST b/lang/cem/libcc/gen/LIST
index cbb4adf..66d70b1 100644 (file)
--- a/lang/cem/libcc/gen/LIST
+++ b/lang/cem/libcc/gen/LIST
@@ -33,6 +33,7 @@ monitor.c
 perror.c
 procentry.c
 qsort.c
+bsearch.c
 rand.c
 seekdir.c
 sleep.c

diff --git a/lang/cem/libcc/gen/bsearch.c b/lang/cem/libcc/gen/bsearch.c
new file mode 100644 (file)
index 0000000..e38bf0c
--- /dev/null
+++ b/lang/cem/libcc/gen/bsearch.c
@@ -0,0 +1,51 @@
+/*  bsearch(3)
+ *
+ *  Author: Terrence Holm          Aug. 1988
+ *
+ *
+ *  Performs a binary search for a given <key> within a sorted
+ *  table. The table contains <count> entries of size <width>
+ *  and starts at <base>.
+ *
+ *  Entries are compared using keycmp( key, entry ), each argument
+ *  is a (char *), the function returns an int < 0, = 0 or > 0
+ *  according to the order of the two arguments.
+ *
+ *  Bsearch(3) returns a pointer to the matching entry, if found,
+ *  otherwise NULL is returned.
+ */
+
+#define  NULL  (char *) 0
+
+
+char *bsearch( key, base, count, width, keycmp )
+  char *key;
+  char *base;
+  unsigned int count;
+  unsigned int width;
+  int  (*keycmp)();
+
+  {
+  char *mid_point;
+  int  cmp;
+
+  while ( count > 0 )
+    {
+    mid_point = base + width * (count >> 1);
+
+    cmp = (*keycmp)( key, mid_point );
+
+    if ( cmp == 0 )
+       return( mid_point );
+
+    if ( cmp < 0 )
+       count >>= 1;
+    else
+       {
+       base  = mid_point + width;
+       count = (count - 1) >> 1;
+       }
+    }
+
+  return( NULL );
+  }