Add support for bsearch() in C library

ChangeLog

@@ -11005,3 +11005,6 @@
 	  must be atomic (2015-09-20).
 
 7.13 2015-xx-xx Gregory Nutt <gnutt@nuttx.org>
+
+	* libc/stdlib/lib_bsearch.c and include/stdlib.h:  Add the bsearch()
+	  function from NetBSD (2015-10-02).

configs

@@ -1 +1 @@
-Subproject commit bb669000c76498d9a0a769948a403784fec897e1
+Subproject commit 5c519b6b0a7a28e785266190874adf297322589d

include/stdlib.h

@@ -200,6 +200,12 @@ FAR void *memalign(size_t, size_t);
 FAR void *zalloc(size_t);
 FAR void *calloc(size_t, size_t);
 
+#ifdef CONFIG_CAN_PASS_STRUCTS
+struct mallinfo mallinfo(void);
+#else
+int      mallinfo(struct mallinfo *info);
+#endif
+
 /* Arithmetic */
 
 int      abs(int j);
@@ -226,11 +232,11 @@ int      mkstemp(FAR char *path_template);
 void     qsort(FAR void *base, size_t nmemb, size_t size,
                int (*compar)(FAR const void *, FAR const void *));
 
-#ifdef CONFIG_CAN_PASS_STRUCTS
-struct mallinfo mallinfo(void);
-#else
-int      mallinfo(struct mallinfo *info);
-#endif
+/* Binary search */
+
+FAR void *bsearch(FAR const void *key, FAR const void *base, size_t nel,
+                  size_t width, CODE int (*compar)(FAR const void *,
+                  FAR const void *));
 
 #undef EXTERN
 #if defined(__cplusplus)

libc/stdlib/Make.defs

@@ -37,7 +37,7 @@
 
 CSRCS += lib_abs.c lib_abort.c lib_div.c lib_ldiv.c lib_lldiv.c
 CSRCS += lib_imaxabs.c lib_itoa.c lib_labs.c lib_llabs.c
-CSRCS += lib_rand.c lib_qsort.c
+CSRCS += lib_bsearch.c lib_rand.c lib_qsort.c
 CSRCS += lib_strtol.c lib_strtoll.c lib_strtoul.c lib_strtoull.c
 CSRCS += lib_strtod.c lib_checkbase.c
 

libc/stdlib/lib_bsearch.c

@@ -0,0 +1,138 @@
+/*****************************************************************************
+ * libc/stdlib/lib_bsearch.c
+ *
+ *   Copyright (c) 1990, 1993
+ *   The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *      This product includes software developed by the University of
+ *      California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *****************************************************************************/
+
+/*****************************************************************************
+ * Included Files
+ *****************************************************************************/
+
+#include <stdlib.h>
+#include <assert.h>
+
+/*****************************************************************************
+ * Public Functions
+ *****************************************************************************/
+
+/*****************************************************************************
+ * Name: bsearch
+ *
+ * Description:
+ *   Per OpenGroup.org:
+ *
+ *   The bsearch() function will search an array of nel objects, the initial
+ *   element of which is pointed to by 'base', for an element that matches
+ *   the object pointed to by 'key'. The size of each element in the array
+ *   is specified by 'width'. If the nel argument has the value zero, the
+ *   comparison function pointed to by 'compar' will not be called and no
+ *   match will be found.
+ *
+ *   The comparison function pointed to by 'compar' will be called with two
+ *   arguments that point to the 'key' object and to an array element, in
+ *   that order.
+ *
+ *   The application will ensure that the comparison function pointed to by
+ *   'compar 'does not alter the contents of the array. The implementation
+ *   may reorder elements of the array between calls to the comparison
+ *   function, but will not alter the contents of any individual element.
+ *
+ *   The implementation will ensure that the first argument is always a
+ *   pointer to the 'key'.
+ *
+ *   When the same objects (consisting of width bytes, irrespective of their
+ *   current positions in the array) are passed more than once to the
+ *   comparison function, the results will be consistent with one another.
+ *   That is, the same object will always compare the same way with the key.
+ *
+ *   The application will ensure that the function returns an integer less
+ *   than, equal to, or greater than 0 if the key object is considered,
+ *   respectively, to be less than, to match, or to be greater than the
+ *   array element. The application will ensure that the array consists of
+ *   all the elements that compare less than, all the elements that compare
+ *   equal to, and all the elements that compare greater than the key
+ *   object, in that order.
+ *
+ * Returned Value:
+ *   The bsearch() function will return a pointer to a matching member of
+ *   the array, or a null pointer if no match is found. If two or more
+ *   members compare equal, which member is returned is unspecified.
+ *
+ * Notes from the NetBSD version:
+ *   The code below is a bit sneaky.  After a comparison fails, we divide
+ *   the work in half by moving either left or right. If 'lim' is odd,
+ *   moving left simply involves halving 'lim': e.g., when 'lim' is 5 we
+ *   look at item 2, so we change 'lim' to 2 so that we will look at items
+ *   0 & 1.  If 'lim' is even, the same applies.  If 'lim' is odd, moving
+ *   right again involes halving 'lim', this time moving the base up one
+ *   item past 'ptr': e.g., when 'lim' is 5 we change base to item 3 and
+ *   make 'lim' 2 so that we will look at items 3 and 4.  If 'lim' is
+ *   even, however, we have to shrink it by one before halving: e.g.,
+ *   when 'lim' is 4, we still looked at item 2, so we have to make 'lim'
+ *   3, then halve, obtaining 1, so that we will only look at item 3.
+ *
+ *****************************************************************************/
+
+FAR void *bsearch(FAR const void *key, FAR const void *base, size_t nel,
+                  size_t width, CODE int (*compar)(FAR const void *,
+                  FAR const void *))
+{
+  FAR const void *ptr;
+  size_t lim;
+  int cmp;
+
+  DEBUGASSERT(key != NULL);
+  DEBUGASSERT(base != NULL || nel == 0);
+  DEBUGASSERT(compar != NULL);
+
+  for (lim = nel; lim != 0; lim >>= 1)
+    {
+      ptr   = base + (lim >> 1) * width;
+      cmp = (*compar)(key, ptr);
+
+      if (cmp == 0)
+        {
+          return (FAR void *)ptr;
+        }
+
+      if (cmp > 0)
+        {
+          /* key > ptr: move right (else move left) */
+
+          base = (FAR const char *)ptr + width;
+          lim--;
+        }
+    }
+
+  return NULL;
+}