libs/libc/wchar: add wcsstr implementation

Signed-off-by: guoshichao <[email protected]>

Author: extinguish

libs/libc/wchar/CMakeLists.txt

@@ -59,4 +59,5 @@ target_sources(
           lib_wcsncmp.c
           lib_wcscspn.c
           lib_wcspbrk.c
-          lib_wcsspn.c)
+          lib_wcsspn.c
+          lib_wcsstr.c)

libs/libc/wchar/Make.defs

@@ -29,6 +29,7 @@ CSRCS += lib_swprintf.c lib_mbsnrtowcs.c lib_wcsnrtombs.c lib_mbsinit.c
 CSRCS += lib_mbrlen.c lib_mbsrtowcs.c lib_wcsrtombs.c lib_wcscpy.c
 CSRCS += lib_wcscat.c lib_wcslcat.c lib_wcsncat.c lib_wcsrchr.c lib_wcschr.c
 CSRCS += lib_wcsncpy.c lib_wcsncmp.c lib_wcscspn.c lib_wcspbrk.c lib_wcsspn.c
+CSRCS += lib_wcsstr.c
 
 # Add the wchar directory to the build
 

libs/libc/wchar/lib_wcsstr.c

@@ -0,0 +1,213 @@
+/****************************************************************************
+ * libs/libc/wchar/lib_wcsstr.c
+ *
+ * Copyright © 2005-2014 Rich Felker, et al.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <wchar.h>
+#include <sys/param.h>
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static FAR wchar_t *twoway_wcsstr(FAR const wchar_t *h, FAR const wchar_t *n)
+{
+  FAR const wchar_t *z;
+  size_t l;
+  size_t ip;
+  size_t jp;
+  size_t k;
+  size_t p;
+  size_t ms;
+  size_t p0;
+  size_t mem;
+  size_t mem0;
+
+  /* Computing length of needle */
+
+  for (l = 0; n[l] && h[l]; l++);
+
+  /* hit the end of h */
+
+  if (n[l]) return 0;
+
+  /* Compute maximal suffix */
+
+  ip = -1; jp = 0; k = p = 1;
+
+  while (jp + k < l)
+    {
+      if (n[ip + k] == n[jp + k])
+        {
+          if (k == p)
+            {
+              jp += p;
+              k = 1;
+            }
+          else k++;
+        }
+      else if (n[ip + k] > n[jp + k])
+        {
+          jp += k;
+          k = 1;
+          p = jp - ip;
+        }
+      else
+        {
+          ip = jp++;
+          k = p = 1;
+        }
+    }
+
+  ms = ip;
+  p0 = p;
+
+  /* And with the opposite comparison */
+
+  ip = -1; jp = 0; k = p = 1;
+  while (jp + k < l)
+    {
+      if (n[ip + k] == n[jp + k])
+        {
+          if (k == p)
+            {
+              jp += p;
+              k = 1;
+            }
+          else k++;
+        }
+      else if (n[ip + k] < n[jp + k])
+        {
+          jp += k;
+          k = 1;
+          p = jp - ip;
+        }
+      else
+        {
+          ip = jp++;
+          k = p = 1;
+        }
+    }
+
+  if (ip + 1 > ms + 1) ms = ip;
+  else p = p0;
+
+  /* Periodic needle? */
+
+  if (wmemcmp(n, n + p, ms + 1))
+    {
+      mem0 = 0;
+      p = MAX(ms, l - ms - 1) + 1;
+    }
+  else
+    {
+      mem0 = l - p;
+    }
+
+  mem = 0;
+
+  /* Initialize incremental end-of-haystack pointer */
+
+  z = h;
+
+  /* Search loop */
+
+  for (; ; )
+    {
+      /* Update incremental end-of-haystack pointer */
+
+      if (z - h < l)
+        {
+          /* Fast estimate for MIN(l,63) */
+
+          size_t grow = l | 63;
+          FAR const wchar_t *z2 = wmemchr(z, 0, grow);
+          if (z2)
+            {
+              z = z2;
+              if (z - h < l) return 0;
+            }
+          else z += grow;
+        }
+
+      /* Compare right half */
+
+      for (k = MAX(ms + 1, mem); n[k] && n[k] == h[k]; k++);
+      if (n[k])
+        {
+          h += k - ms;
+          mem = 0;
+          continue;
+        }
+
+      /* Compare left half */
+
+      for (k = ms + 1; k > mem && n[k - 1] == h[k - 1]; k--);
+
+      if (k <= mem) return (FAR wchar_t *)h;
+      h += p;
+      mem = mem0;
+    }
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: wcsstr
+ *
+ * Description:
+ *    Locate substring of wide string
+ *
+ * Input Parameters:
+ *   h - the wide string to be scanned
+ *   n - the wide string containing the sequence of characters to match
+ *
+ * Returned Value:
+ *   Return a pointer to the first occurrence in "h" of the entire sequence
+ *   of characters specified in "n";
+ *   Return null pointer if the sequence is not present in "h"
+ *
+ ****************************************************************************/
+
+FAR wchar_t *wcsstr(FAR const wchar_t *h, FAR const wchar_t *n)
+{
+  /* Return immediately on empty needle or haystack */
+
+  if (!n[0]) return (FAR wchar_t *)h;
+  if (!h[0]) return 0;
+
+  /* Use faster algorithms for short needles */
+
+  h = wcschr(h, *n);
+  if (!h || !n[1]) return (FAR wchar_t *)h;
+  if (!h[1]) return 0;
+
+  return twoway_wcsstr(h, n);
+}