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| 請問如__builtin_memset 這些API有無文件說明 http://forum.andestech.com/viewtopic.php?f=16&t=664 |
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| Author: | cindy [ Thu Jan 24, 2013 6:05 pm ] |
| Post subject: | 請問如__builtin_memset 這些API有無文件說明 |
Q: 請問如__builtin_memset 這些API有無文件說明？ A:相關GCC預設所支援的built-in function可在這底下這個連結查到： http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html “GCC includes built-in versions of many of the functions in the standard C library. The versions prefixed with __builtin_ are always treated as having the same meaning as the C library function... “ 簡而言之就是像 __builtin_memset，它是和memset語意一模一樣的~ __builtin_ function本來是內建給compiler自己使用的， user如果要用也可以。compiler會認得__builtin_ function的語意， 自動產生code，而且是呼叫function。 少了呼叫function的overhead. |
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