| 0,0 → 1,144 |
|---|
| /* |
| FUNCTION |
| <<memccpy>>---copy memory regions with end-token check |
| |
| ANSI_SYNOPSIS |
| #include <string.h> |
| void* memccpy(void *restrict <[out]>, const void *restrict <[in]>, |
| int <[endchar]>, size_t <[n]>); |
| |
| TRAD_SYNOPSIS |
| void *memccpy(<[out]>, <[in]>, <[endchar]>, <[n]> |
| void *<[out]>; |
| void *<[in]>; |
| int <[endchar]>; |
| size_t <[n]>; |
| |
| DESCRIPTION |
| This function copies up to <[n]> bytes from the memory region |
| pointed to by <[in]> to the memory region pointed to by |
| <[out]>. If a byte matching the <[endchar]> is encountered, |
| the byte is copied and copying stops. |
| |
| If the regions overlap, the behavior is undefined. |
| |
| RETURNS |
| <<memccpy>> returns a pointer to the first byte following the |
| <[endchar]> in the <[out]> region. If no byte matching |
| <[endchar]> was copied, then <<NULL>> is returned. |
| |
| PORTABILITY |
| <<memccpy>> is a GNU extension. |
| |
| <<memccpy>> requires no supporting OS subroutines. |
| |
| */ |
| |
| #include <_ansi.h> |
| #include <stddef.h> |
| #include <string.h> |
| #include <limits.h> |
| |
| /* Nonzero if either X or Y is not aligned on a "long" boundary. */ |
| #define UNALIGNED(X, Y) \ |
| (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1))) |
| |
| /* How many bytes are copied each iteration of the word copy loop. */ |
| #define LITTLEBLOCKSIZE (sizeof (long)) |
| |
| /* Threshhold for punting to the byte copier. */ |
| #define TOO_SMALL(LEN) ((LEN) < LITTLEBLOCKSIZE) |
| |
| /* Macros for detecting endchar */ |
| #if LONG_MAX == 2147483647L |
| #define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080) |
| #else |
| #if LONG_MAX == 9223372036854775807L |
| /* Nonzero if X (a long int) contains a NULL byte. */ |
| #define DETECTNULL(X) (((X) - 0x0101010101010101) & ~(X) & 0x8080808080808080) |
| #else |
| #error long int is not a 32bit or 64bit type. |
| #endif |
| #endif |
| |
| |
| _PTR |
| _DEFUN (memccpy, (dst0, src0, endchar, len0), |
| _PTR __restrict dst0 _AND |
| _CONST _PTR __restrict src0 _AND |
| int endchar0 _AND |
| size_t len0) |
| { |
| |
| #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__) |
| _PTR ptr = NULL; |
| char *dst = (char *) dst0; |
| char *src = (char *) src0; |
| char endchar = endchar0 & 0xff; |
| |
| while (len0--) |
| { |
| if ((*dst++ = *src++) == endchar) |
| { |
| ptr = dst; |
| break; |
| } |
| } |
| |
| return ptr; |
| #else |
| _PTR ptr = NULL; |
| char *dst = dst0; |
| _CONST char *src = src0; |
| long *aligned_dst; |
| _CONST long *aligned_src; |
| char endchar = endchar0 & 0xff; |
| |
| /* If the size is small, or either SRC or DST is unaligned, |
| then punt into the byte copy loop. This should be rare. */ |
| if (!TOO_SMALL(len0) && !UNALIGNED (src, dst)) |
| { |
| unsigned int i; |
| unsigned long mask = 0; |
| |
| aligned_dst = (long*)dst; |
| aligned_src = (long*)src; |
| |
| /* The fast code reads the ASCII one word at a time and only |
| performs the bytewise search on word-sized segments if they |
| contain the search character, which is detected by XORing |
| the word-sized segment with a word-sized block of the search |
| character and then detecting for the presence of NULL in the |
| result. */ |
| for (i = 0; i < LITTLEBLOCKSIZE; i++) |
| mask = (mask << 8) + endchar; |
| |
| |
| /* Copy one long word at a time if possible. */ |
| while (len0 >= LITTLEBLOCKSIZE) |
| { |
| unsigned long buffer = (unsigned long)(*aligned_src); |
| buffer ^= mask; |
| if (DETECTNULL (buffer)) |
| break; /* endchar is found, go byte by byte from here */ |
| *aligned_dst++ = *aligned_src++; |
| len0 -= LITTLEBLOCKSIZE; |
| } |
| |
| /* Pick up any residual with a byte copier. */ |
| dst = (char*)aligned_dst; |
| src = (char*)aligned_src; |
| } |
| |
| while (len0--) |
| { |
| if ((*dst++ = *src++) == endchar) |
| { |
| ptr = dst; |
| break; |
| } |
| } |
| |
| return ptr; |
| #endif /* not PREFER_SIZE_OVER_SPEED */ |
| } |