| /**************************************************************************** |
| * 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); |
| } |