diff options
Diffstat (limited to 'newlib/libc/machine/riscv/memchr.c')
| -rw-r--r-- | newlib/libc/machine/riscv/memchr.c | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/newlib/libc/machine/riscv/memchr.c b/newlib/libc/machine/riscv/memchr.c new file mode 100644 index 0000000..62a7d19 --- /dev/null +++ b/newlib/libc/machine/riscv/memchr.c @@ -0,0 +1,152 @@ +/* +FUNCTION + <<memchr>>---find character in memory + +INDEX + memchr + +SYNOPSIS + #include <string.h> + void *memchr(const void *<[src]>, int <[c]>, size_t <[length]>); + +DESCRIPTION + This function searches memory starting at <<*<[src]>>> for the + character <[c]>. The search only ends with the first + occurrence of <[c]>, or after <[length]> characters; in + particular, <<NUL>> does not terminate the search. + +RETURNS + If the character <[c]> is found within <[length]> characters + of <<*<[src]>>>, a pointer to the character is returned. If + <[c]> is not found, then <<NULL>> is returned. + +PORTABILITY +<<memchr>> is ANSI C. + +<<memchr>> requires no supporting OS subroutines. + +QUICKREF + memchr ansi pure +*/ + +#include <sys/asm.h> +#include <stddef.h> +#include "rv_string.h" + +// Move size +#if __riscv_zilsd +#define MV_SZ 8 +#else +#define MV_SZ SZREG +#endif + + +void * +memchr (const void *src_void, + int c, + size_t length) +{ + const unsigned char *src = (const unsigned char *) src_void; + unsigned char d = c; + +#if !defined(PREFER_SIZE_OVER_SPEED) && !defined(__OPTIMIZE_SIZE__) + size_t align = (uintptr_t) src & (MV_SZ - 1); + + if (align) + { + align = MV_SZ - align; + + if (length < align) align = length; + + switch (align) + { +#if MV_SZ == 8 + case 7: + if (*src++ == d) return (void *) (src - 1); + case 6: + if (*src++ == d) return (void *) (src - 1); + case 5: + if (*src++ == d) return (void *) (src - 1); + case 4: + if (*src++ == d) return (void *) (src - 1); +#endif /* MV_SZ == 8 */ + case 3: + if (*src++ == d) return (void *) (src - 1); + case 2: + if (*src++ == d) return (void *) (src - 1); + case 1: + if (*src++ == d) return (void *) (src - 1); + } + + length -= align; + } + + const unsigned char *end_addr = src + (length & ~(MV_SZ - 1)); + + if (src < end_addr) + { + uintxlen_t mask = __libc_splat_byte(d); + + do + { + uintlslen_t val = *(uintlslen_t*) src; + uintxlen_t word1 = val ^ mask; + + if (__libc_detect_null(word1)) + { +#if __riscv_zbb + word1 = ~__LIBC_RISCV_ZBB_ORC_B(word1); + word1 = __LIBC_RISCV_ZBB_CNT_Z(word1); + + return (void *) (src + (word1 >> 3)); +#else /* not __riscv_zbb */ + if (*src++ == d) return (void *) (src - 1); + if (*src++ == d) return (void *) (src - 1); + if (*src++ == d) return (void *) (src - 1); +#if __riscv_xlen == 64 + if (*src++ == d) return (void *) (src - 1); + if (*src++ == d) return (void *) (src - 1); + if (*src++ == d) return (void *) (src - 1); + if (*src++ == d) return (void *) (src - 1); +#endif /* __riscv_xlen == 64 */ + return (void *) src; +#endif /* __riscv_zbb */ + } +#if __riscv_zilsd + uintxlen_t word2 = (val >> 32); + word2 ^= mask; + + if (__libc_detect_null(word2)) + { + src += MV_SZ / 2; +#if __riscv_zbb + word2 = ~__LIBC_RISCV_ZBB_ORC_B(word2); + word2 = __LIBC_RISCV_ZBB_CNT_Z(word2); + + return (void *) (src + (word2 >> 3)); +#else /* not __riscv_zbb */ + if (*src++ == d) return (void *) (src - 1); + if (*src++ == d) return (void *) (src - 1); + if (*src++ == d) return (void *) (src - 1); + return (void *) src; +#endif /* __riscv_zbb */ + } +#endif /* __riscv_zilsd */ + + src += MV_SZ; + } while (src < end_addr); + + length &= MV_SZ - 1; + } + +#endif /* not PREFER_SIZE_OVER_SPEED */ + + while (length--) + { + if (*src == d) + return (void *) src; + src++; + } + + return NULL; +} |