Messages in this thread | | | Date | Sun, 27 Mar 2016 14:44:01 +0200 | From | Sam Ravnborg <> | Subject | Re: [PATCH 01/31] bitops: add parity functions |
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Hi Zeng.
Looking through the arch specific implementations of __arch_parity(). Some architectures uses #defines, other uses inline static functions.
Any particular reason that you select one approach over the other in the different cases?
ia64: +#define __arch_parity32(x) ((unsigned int) __arch_parity64((x) & 0xfffffffful)) +#define __arch_parity16(x) ((unsigned int) __arch_parity64((x) & 0xfffful)) +#define __arch_parity8(x) ((unsigned int) __arch_parity64((x) & 0xfful)) +#define __arch_parity4(x) ((unsigned int) __arch_parity64((x) & 0xful))
tile: +static inline unsigned int __arch_parity32(unsigned int w) +{ + return __builtin_popcount(w) & 1; +} + +static inline unsigned int __arch_parity16(unsigned int w) +{ + return __arch_parity32(w & 0xffff); +} + +static inline unsigned int __arch_parity8(unsigned int w) +{ + return __arch_parity32(w & 0xff); +} + +static inline unsigned int __arch_parity4(unsigned int w) +{ + return __arch_parity32(w & 0xf); +}
Just two examples.
Adding the parity helpers seems like veny nice simplifications.
A few comments to some of those I looked at. (I am not subscribed to lkml, so you get it as comments here)
[PATCH 21/31] mtd: use parity16 in ssfdc.c The original code semes to check that the parity equals the value of first bit in the address. This seems lost after the conversion.
[PATCH 20/31] scsi: use parity32 in isci/phy.c + if (parity32(phy_cap.all)) phy_cap.parity = 1; Could be written like this - simpler IMO: phy_cap.parity = parity32(phy_cap.all);
Sam
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