bithacks.h - bit hacks header file

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Ben Permalink
January 14, 2010, 10:45

Sorry, that did not work as expected :(

B_SET(x, 31) fails because:
- 1 is int (32-bit)
- x is unsigned long (64-bit)
- (1long->unsigned long will sign
extend the rhs of |=

One fix: use typeof
#define BIT_MASK(x,n) ( ((__typeof((x)))1)
#define B_SET(x,n) ((x)|=BIT_MASK((x),(n)))

In c++ one could use templates.

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