Atomic Operations (continuing on from Masking Interrupts?)

Luke Diamand lgd@virata.com
Wed Jul 7 03:47:00 GMT 1999


"Robert J. Brown" wrote:
> 
> 
> The problem is that there is no language enforced way to insure that
> enables are balanced with disables, and inhibits are balanced with
> restores.  The use of a subroutine that takes a thunk as its sole
> argument, such as my "without_pre_emption(thunk)" example above,
> forces the programmer to keep things balanced.  The only real
> trouble-maker is throwing an exception, or taking a longjump.  Lisp
> provides "unwind-protect" for that situation.

Use C++. Create a classlet where the constructor saves the interrupt
mask and disables interrupts, and the destructor restores the status quo
ante. Create one of these on the stack; when it goes out of scope
interrupts are restored.

Of course you then suffer the perils of C++, but that's another story
;-)

HTH!
Luke Diamand

-- 
Virata http://www.virata.com
Cambridge
Tel: +44 1223 566919      Fax: +44 1223 566915
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