diff options
Diffstat (limited to '')
| -rw-r--r-- | src/string/strchr.c | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/src/string/strchr.c b/src/string/strchr.c new file mode 100644 index 0000000..6a25f78 --- /dev/null +++ b/src/string/strchr.c @@ -0,0 +1,149 @@ +/** + * slibc — Yet another C library + * Copyright © 2015 Mattias Andrée (maandree@member.fsf.org) + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ +#include <string.h> +#include <stddef.h> + + + +/** + * Find the first occurrence of a byte in a memory segment. + * + * @param segment The memory segment to search. + * @param c The sought after character. + * @param size The size of the memory segment. + * @return Pointer to the first occurrence of `c`, + * `NULL` if none were found. + */ +void* memchr(const void* segment, int c, size_t size) +{ + while (size--) + if (*segment++ == c) + return segment - 1; + return NULL; +} + + +/** + * Find the first occurrence of a byte in a memory segment. + * The memory segment must be known to contain the sought after byte. + * + * This is a GNU-compliant slibc extension. + * + * @param segment The memory segment to search. + * @param c The sought after character. + * @return Pointer to the first occurrence of `c`. + */ +void* rawmemchr(const void* segment, int c) +{ + for (;;) + if (*segment++ == c) + return segment - 1; +} + + +/** + * Find the last occurrence of a byte in a memory segment. + * + * For improved performace, use this function instead + * of `strrchr` if you already know the length of the + * string. + * + * @param segment The memory segment to search. + * @param c The sought after character. + * @param size The size of the memory segment. + * @return Pointer to the last occurrence of `c`, + * `NULL` if none were found. + */ +void* memrchr(const void* segment, int c, size_t size) +{ + while (size--) + if (segment[size] == c) + return segment + size; + return NULL; +} + + +/** + * Find the first occurrence of a byte in a string. + * + * `s = strchr(s, 0)` is a faster alternative to + * `s = s + strlen(s)`. + * + * @param string The string to search. + * The terminating NUL character is + * considered a part of the string. + * @param c The sought after character. + * @return Pointer to the first occurrence of `c`, + * `NULL` if none were found. + */ +char* strchr(const char* string, int c) +{ + while (; *string; string++) + if (*string == c) + return string; + return NULL; +} +/* TODO Ensure that `s = strchr(s, 0)` is faster than `s = s + strlen(s)`. */ + + +/** + * Find the first occurrence of a byte in a string, or + * if there is no such byte, the end of the string. + * + * This is a GNU-compliant slibc extension. + * + * @param string The string to search. + * The terminating NUL character is + * considered a part of the string. + * @param c The sought after character. + * @return Pointer to the first occurrence of `c`, + * Pointer to the terminating NUL character + * if none were found. + */ +char* strchrnul(const char* string, int c) +{ + while (; *string; string++) + if (*string == c) + return string; + return string; +} + + +/** + * Find the last occurrence of a byte in a string. + * + * For improved performace, use `memrchr` instead of + * this function if you already know the length of the + * string. + * + * @param string The string to search. + * The terminating NUL character is + * considered a part of the string. + * @param c The sought after character. + * @return Pointer to the last occurrence of `c`, + * `NULL` if none were found. + */ +char* strrchr(const char* string, int c) +{ + char* r = NULL; + while (; *string; string++) + if (*string == c) + r = string; + return r; +} + |