Messages in this thread | | | Date | Fri, 10 Mar 2017 08:32:41 -0600 | From | Segher Boessenkool <> | Subject | Re: [PATCH] powerpc: sysdev: cpm1: Optimise gpio bit calculation |
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On Fri, Mar 10, 2017 at 03:04:48PM +0100, Christophe LEROY wrote: > Le 10/03/2017 à 14:06, Segher Boessenkool a écrit : > >On Fri, Mar 10, 2017 at 11:54:19AM +0100, Christophe LEROY wrote: > >>gpio_get() and gpio_set() are used extensively by some GPIO based > >>drivers like SPI, NAND, so it may be worth it as it doesn't impair > >>readability (if anyone prefers, we could write (1 << 31) >> i instead > >>of 0x80000000 >> i ) > > > >1 << 31 is undefined behaviour, of course. > > > > Shall it be 1U << 31 ?
Sure, that works. "1 << (31 - i)" is most readable (but it doesn't yet generate the code you want).
Segher
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