From 5278f6def4248391a481382bd7b0042b04c829f2 Mon Sep 17 00:00:00 2001 From: Richard Qin Date: Tue, 21 Apr 2026 23:16:50 +0800 Subject: feat: add string manipulation functions derived from musl libc This commit introduces a variety of string manipulation functions, including: - `memmem`: Searches for a substring in a memory area. - `memmove`: Safely copies memory areas, handling overlaps. - `mempcpy`: Copies memory and returns a pointer to the end of the destination. - `memrchr`: Finds the last occurrence of a character in a memory area. - `memset`: Fills a memory area with a specified value. - `rindex`: Returns the last occurrence of a character in a string. - `stpcpy` and `stpncpy`: Copies strings and returns a pointer to the end. - `strcat`, `strchr`, `strcspn`, `strlcat`, `strlcpy`, `strlen`, `strncat`, `strncmp`, `strncpy`, `strnlen`, `strpbrk`, `strrchr`, `strstr`, `strtok`, and `strtok_r`: Various string manipulation functions for concatenation, searching, and tokenization. Assembly implementations for `memcpy`, `memmove`, and `memset` are also included for optimized performance on x86_64 architectures. --- na/lib/string/strspn.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) create mode 100644 na/lib/string/strspn.c (limited to 'na/lib/string/strspn.c') diff --git a/na/lib/string/strspn.c b/na/lib/string/strspn.c new file mode 100644 index 0000000..f27710d --- /dev/null +++ b/na/lib/string/strspn.c @@ -0,0 +1,23 @@ +/* SPDX-License-Identifier: MIT */ +/* Derived from musl libc (Copyright © 2005-2020 Rich Felker, et al.) */ + +#include + +#define BITOP(a,b,op) \ + ((a)[(size_t)(b)/(8*sizeof *(a))] op (size_t)1<<((size_t)(b)%(8*sizeof *(a)))) + +size_t strspn(const char *s, const char *c) +{ + const char *a = s; + size_t byteset[32/sizeof(size_t)] = { 0 }; + + if (!c[0]) return 0; + if (!c[1]) { + for (; *s == *c; s++); + return s-a; + } + + for (; *c && BITOP(byteset, *(unsigned char *)c, |=); c++); + for (; *s && BITOP(byteset, *(unsigned char *)s, &); s++); + return s-a; +} -- cgit v1.2.3