diff options
Diffstat (limited to 'string/strspn.c')
| -rw-r--r-- | string/strspn.c | 57 |
1 files changed, 42 insertions, 15 deletions
diff --git a/string/strspn.c b/string/strspn.c index f0635c1..f98340b 100644 --- a/string/strspn.c +++ b/string/strspn.c @@ -16,32 +16,59 @@ <http://www.gnu.org/licenses/>. */ #include <string.h> +#include <stdint.h> #undef strspn #ifndef STRSPN -#define STRSPN strspn +# define STRSPN strspn #endif /* Return the length of the maximum initial segment of S which contains only characters in ACCEPT. */ size_t -STRSPN (const char *s, const char *accept) +STRSPN (const char *str, const char *accept) { - const char *p; - const char *a; - size_t count = 0; - - for (p = s; *p != '\0'; ++p) + if (accept[0] == '\0') + return 0; + if (__glibc_unlikely (accept[1] == '\0')) { - for (a = accept; *a != '\0'; ++a) - if (*p == *a) - break; - if (*a == '\0') - return count; - else - ++count; + const char *a = str; + for (; *str == *accept; str++); + return str - a; } - return count; + /* Use multiple small memsets to enable inlining on most targets. */ + unsigned char table[256]; + unsigned char *p = memset (table, 0, 64); + memset (p + 64, 0, 64); + memset (p + 128, 0, 64); + memset (p + 192, 0, 64); + + unsigned char *s = (unsigned char*) accept; + /* Different from strcspn it does not add the NULL on the table + so can avoid check if str[i] is NULL, since table['\0'] will + be 0 and thus stopping the loop check. */ + do + p[*s++] = 1; + while (*s); + + s = (unsigned char*) str; + if (!p[s[0]]) return 0; + if (!p[s[1]]) return 1; + if (!p[s[2]]) return 2; + if (!p[s[3]]) return 3; + + s = (unsigned char *) ((uintptr_t)(s) & ~3); + unsigned int c0, c1, c2, c3; + do { + s += 4; + c0 = p[s[0]]; + c1 = p[s[1]]; + c2 = p[s[2]]; + c3 = p[s[3]]; + } while ((c0 & c1 & c2 & c3) != 0); + + size_t count = s - (unsigned char *) str; + return (c0 & c1) == 0 ? count + c0 : count + c2 + 2; } libc_hidden_builtin_def (strspn) |