wat is use of pragma directive in embedded sys ??

aleemakhtar1@gmail.com wrote:
> wat is use of pragma directive in embedded sys ??

The "#pragma" preprocessing directive generally controls some
implementation-specific behaviour. The C99 standard specifies
3 "STDC" options which can be controlled with "#pragma", but
otherwise you need to refer to your compiler documentation.

aleemakhtar1@gmail.com wrote:

> wat is use of pragma directive in embedded sys ??

From n1256:

6.10.6 Pragma directive
Semantics

1 A preprocessing directive of the form

# pragma pp-tokensopt new-line

where the preprocessing token STDC does not immediately follow pragma in
the directive (prior to any macro replacement)152) causes the
implementation to behave in an implementation-defined manner. The
behavior might cause translation to fail or cause the
translator or the resulting program to behave in a non-conforming
manner. Any such pragma that is not recognized by the implementation is
ignored.

2 If the preprocessing token STDC does immediately follow pragma in the
directive (prior to any macro replacement), then no macro replacement
is performed on the directive, and the directive shall have one of the
following forms153) whose meanings are described elsewhere:

#pragma STDC FP_CONTRACT on-off-switch
#pragma STDC FENV_ACCESS on-off-switch
#pragma STDC CX_LIMITED_RANGE on-off-switch

on-off-switch: one of
ON OFF DEFAULT

aleemakhtar1@gmail.com wrote:

> wat is use of pragma directive in embedded sys ??
It is implementation-defined. [1] If you're interested on a particular
system, you should look it up on its documentation, and maybe ask in a
newsgroup about it.

[1] Except C99's #pragma STDC about floating point environment.


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<aleemakhtar1@gmail.com> wrote in message
news:e7c83d3f-b89b-40f6-b559-31cab61a1c13@v67g2000hse.googlegroups.com...
> wat is use of pragma directive in embedded sys ??

some are:
-> control over the "section" into which the compiler places the code and/or
data
-> control over the "addressing mode" used for accessing the data
-> control over floating point
-> control over enabling/disabling of certain optimizations etc