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今天看ANSI_C 99的时候看到一段:
Alternatively, an implementation might perform various optimizations within each translation unit, such
that the actual semantics would agree with the abstract semantics only when making function calls across
translation unit boundaries. In such an implementation, at the time of each function entry and function
return where the calling function and the called function are in different translation units, the values of all
externally linked objects and of all objects accessible via pointers therein would agree with the abstract
semantics. Furthermore, at the time of each such function entry the values of the parameters of the called
function and of all objects accessible via pointers therein would agree with the abstract semantics. In this
type of implementation, objects referred to by interrupt service routines activated by the signal function
would require explicit specification of volatile storage, as well as other implementation-defined
restrictions.
英语不太好,没明白abstract semantics和actual semantics具体指什么。对volatile的作用也不是很明白。
搜了下,说是告诉编译器不要放在寄存器,而是直接从对应内存中读。有些明白,但不确定。
而且回头再看上面那段时还是不着边绪,希望能有人解释下或给提示下...
先谢谢了...
[ 本帖最后由 zzdts 于 2007-3-29 23:30 编辑 ] |
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