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swd: Improve parity calculation and move it to types.h

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It could be reused by SWD drivers and in other places.

Change-Id: Ieed0cf70c111a73d3a42ed59f46a0cdd177a73d5
Signed-off-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>
Reviewed-on: http://openocd.zylin.com/1957
Tested-by: jenkins
Reviewed-by: Paul Fertser <fercerpav@gmail.com>
This commit is contained in:
Andreas Fritiofson
2014-02-17 00:27:09 +01:00
parent 0e95ec4070
commit 36772a7ed0
2 changed files with 20 additions and 12 deletions
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19
src/helper/types.h
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@@ -270,6 +270,25 @@ static inline void buf_bswap32(uint8_t *dst, const uint8_t *src, size_t len)
}
}
/**
* Calculate the (even) parity of a 32-bit datum.
* @param x The datum.
* @return 1 if the number of set bits in x is odd, 0 if it is even.
*/
static inline int parity_u32(uint32_t x)
{
#ifdef __GNUC__
return __builtin_parityl(x);
#else
x ^= x >> 16;
x ^= x >> 8;
x ^= x >> 4;
x ^= x >> 2;
x ^= x >> 1;
return x & 1;
#endif
}
#if defined(__ECOS)
/* eCos plain lacks these definition... A series of upstream patches