diff options
Diffstat (limited to 'include/m_string.h')
| -rw-r--r-- | include/m_string.h | 75 |
1 files changed, 6 insertions, 69 deletions
diff --git a/include/m_string.h b/include/m_string.h index 9eb0e1e13ff..ba906e2e62c 100644 --- a/include/m_string.h +++ b/include/m_string.h @@ -90,6 +90,12 @@ extern const char _dig_vec_lower[]; extern char *strmov_overlapp(char *dest, const char *src); +#if defined(_lint) || defined(FORCE_INIT_OF_VARS) +#define LINT_INIT_STRUCT(var) bzero(&var, sizeof(var)) /* No uninitialize-warning */ +#else +#define LINT_INIT_STRUCT(var) +#endif + /* Prototypes for string functions */ extern void bmove_upp(uchar *dst,const uchar *src,size_t len); @@ -215,75 +221,6 @@ struct st_mysql_const_unsigned_lex_string }; typedef struct st_mysql_const_unsigned_lex_string LEX_CUSTRING; -/* SPACE_INT is a word that contains only spaces */ -#if SIZEOF_INT == 4 -#define SPACE_INT 0x20202020 -#elif SIZEOF_INT == 8 -#define SPACE_INT 0x2020202020202020 -#else -#error define the appropriate constant for a word full of spaces -#endif - -/** - Skip trailing space. - - On most systems reading memory in larger chunks (ideally equal to the size of - the chinks that the machine physically reads from memory) causes fewer memory - access loops and hence increased performance. - This is why the 'int' type is used : it's closest to that (according to how - it's defined in C). - So when we determine the amount of whitespace at the end of a string we do - the following : - 1. We divide the string into 3 zones : - a) from the start of the string (__start) to the first multiple - of sizeof(int) (__start_words) - b) from the end of the string (__end) to the last multiple of sizeof(int) - (__end_words) - c) a zone that is aligned to sizeof(int) and can be safely accessed - through an int * - 2. We start comparing backwards from (c) char-by-char. If all we find is - space then we continue - 3. If there are elements in zone (b) we compare them as unsigned ints to a - int mask (SPACE_INT) consisting of all spaces - 4. Finally we compare the remaining part (a) of the string char by char. - This covers for the last non-space unsigned int from 3. (if any) - - This algorithm works well for relatively larger strings, but it will slow - the things down for smaller strings (because of the additional calculations - and checks compared to the naive method). Thus the barrier of length 20 - is added. - - @param ptr pointer to the input string - @param len the length of the string - @return the last non-space character -*/ - -static inline const uchar *skip_trailing_space(const uchar *ptr,size_t len) -{ - const uchar *end= ptr + len; - - if (len > 20) - { - const uchar *end_words= (const uchar *)(intptr) - (((ulonglong)(intptr)end) / SIZEOF_INT * SIZEOF_INT); - const uchar *start_words= (const uchar *)(intptr) - ((((ulonglong)(intptr)ptr) + SIZEOF_INT - 1) / SIZEOF_INT * SIZEOF_INT); - - DBUG_ASSERT(((ulonglong)(intptr)ptr) >= SIZEOF_INT); - if (end_words > ptr) - { - while (end > end_words && end[-1] == 0x20) - end--; - if (end[-1] == 0x20 && start_words < end_words) - while (end > start_words && ((unsigned *)end)[-1] == SPACE_INT) - end -= SIZEOF_INT; - } - } - while (end > ptr && end[-1] == 0x20) - end--; - return (end); -} - static inline void lex_string_set(LEX_STRING *lex_str, const char *c_str) { lex_str->str= (char *) c_str; |