C library: Add ffs(). Add strings.h. Move strcasecmp, strncasecmp, bzero, bcmp, and bcopy to where they belong in strings.h.h, not string.h. bzero, bcmp, and bcopy are legacy functions; the contemporary counterparts should be used instead.

libc/string/Make.defs

@@ -1,7 +1,7 @@
 ############################################################################
 # libc/string/Make.defs
 #
-#   Copyright (C) 2011-2012, 2014, 2016 Gregory Nutt. All rights reserved.
+#   Copyright (C) 2011-2012, 2014, 2016-2017 Gregory Nutt. All rights reserved.
 #   Author: Gregory Nutt <gnutt@nuttx.org>
 #
 # Redistribution and use in source and binary forms, with or without
@@ -35,13 +35,14 @@
 
 # Add the string C files to the build
 
-CSRCS += lib_isbasedigit.c lib_memset.c lib_memchr.c lib_memccpy.c
-CSRCS += lib_memcmp.c lib_memmove.c lib_skipspace.c lib_stpcpy.c
-CSRCS += lib_strcasecmp.c lib_strcat.c lib_strchr.c lib_strcpy.c
-CSRCS += lib_strcmp.c lib_strcspn.c lib_strdup.c lib_strerror.c lib_strlen.c
-CSRCS += lib_strnlen.c lib_strncasecmp.c lib_strncat.c lib_strncmp.c
-CSRCS += lib_strncpy.c lib_strndup.c lib_strcasestr.c lib_strpbrk.c
-CSRCS += lib_strrchr.c lib_strspn.c lib_strstr.c lib_strtok.c lib_strtokr.c
+CSRCS += lib_ffs.c lib_isbasedigit.c lib_memset.c lib_memchr.c
+CSRCS += lib_memccpy.c lib_memcmp.c lib_memmove.c lib_skipspace.c
+CSRCS += lib_stpcpy.c lib_strcasecmp.c lib_strcat.c lib_strchr.c
+CSRCS += lib_strcpy.c lib_strcmp.c lib_strcspn.c lib_strdup.c
+CSRCS += lib_strerror.c lib_strlen.c lib_strnlen.c lib_strncasecmp.c
+CSRCS += lib_strncat.c lib_strncmp.c lib_strncpy.c lib_strndup.c
+CSRCS += lib_strcasestr.c lib_strpbrk.c lib_strrchr.c lib_strspn.c
+CSRCS += lib_strstr.c lib_strtok.c lib_strtokr.c
 
 ifneq ($(CONFIG_LIBC_ARCH_MEMCPY),y)
 ifeq ($(CONFIG_MEMCPY_VIK),y)

libc/string/lib_ffs.c

@@ -0,0 +1,87 @@
+/****************************************************************************
+ * libc/string/lib_ffs.c
+ *
+ *   Copyright (C) 2017 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * 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. Neither the name NuttX 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 COPYRIGHT HOLDERS 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
+ * COPYRIGHT OWNER 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 <strings.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define NBITS (8 * sizeof(unsigned int))
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: ffs
+ *
+ * Description:
+ *   The ffs() function will find the first bit set (beginning with the least
+ *   significant bit) in i, and return the index of that bit. Bits are
+ *   numbered starting at one (the least significant bit).
+ *
+ * Returned Value:
+ *   The ffs() function will return the index of the first bit set. If i is
+ *   0, then ffs() will return 0.
+ *
+ ****************************************************************************/
+
+int ffs(int j)
+{
+  int ret = 0;
+
+  if (j != 0)
+    {
+      unsigned int value = (unsigned int)j;
+      int bitno;
+
+      for (bitno = 1; bitno <= NBITS; bitno++, value >>= 1)
+        {
+          if ((value & 1) != 0)
+            {
+              ret = bitno;
+              break;
+            }
+        }
+    }
+
+  return ret;
+}

libc/string/lib_memset.c

@@ -1,4 +1,3 @@
-
 /****************************************************************************
  * libc/string/lib_memset.c
  *

libc/string/lib_strcasecmp.c

@@ -39,7 +39,7 @@
 
 #include <nuttx/config.h>
 
-#include <string.h>
+#include <strings.h>
 #include <ctype.h>
 
 /****************************************************************************

libc/string/lib_strncasecmp.c

@@ -40,7 +40,7 @@
 #include <nuttx/config.h>
 
 #include <sys/types.h>
-#include <string.h>
+#include <strings.h>
 #include <ctype.h>
 
 /****************************************************************************