/usr/include/m4ri/parity.h is in libm4ri-dev 0.0.20080521-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 | /**
* \file parity.h
*
* \brief Compute the parity of 64 words in parallel.
*
* \author David Harvey
*/
#define MIX32(a, b) (((((a) << 32) ^ (a)) >> 32) + \
((((b) >> 32) ^ (b)) << 32))
#define MIX16(a, b) (((((a) >> 16) ^ (a)) & 0x0000FFFF0000FFFF) + \
((((b) << 16) ^ (b)) & 0xFFFF0000FFFF0000));
#define MIX8(a, b) (((((a) >> 8) ^ (a)) & 0x00FF00FF00FF00FF) + \
((((b) << 8) ^ (b)) & 0xFF00FF00FF00FF00));
#define MIX4(a, b) (((((a) >> 4) ^ (a)) & 0x0F0F0F0F0F0F0F0F) + \
((((b) << 4) ^ (b)) & 0xF0F0F0F0F0F0F0F0));
#define MIX2(a, b) (((((a) >> 2) ^ (a)) & 0x3333333333333333) + \
((((b) << 2) ^ (b)) & 0xCCCCCCCCCCCCCCCC));
#define MIX1(a, b) (((((a) >> 1) ^ (a)) & 0x5555555555555555) + \
((((b) << 1) ^ (b)) & 0xAAAAAAAAAAAAAAAA));
static inline word _parity64_helper(word* buf)
{
word a0, a1, b0, b1, c0, c1;
a0 = MIX32(buf[0x20], buf[0x00]);
a1 = MIX32(buf[0x30], buf[0x10]);
b0 = MIX16(a1, a0);
a0 = MIX32(buf[0x28], buf[0x08]);
a1 = MIX32(buf[0x38], buf[0x18]);
b1 = MIX16(a1, a0);
c0 = MIX8(b1, b0);
a0 = MIX32(buf[0x24], buf[0x04]);
a1 = MIX32(buf[0x34], buf[0x14]);
b0 = MIX16(a1, a0);
a0 = MIX32(buf[0x2C], buf[0x0C]);
a1 = MIX32(buf[0x3C], buf[0x1C]);
b1 = MIX16(a1, a0);
c1 = MIX8(b1, b0);
return MIX4(c1, c0);
}
/**
* \brief Computes parity of each of buf[0], buf[1], ..., buf[63].
* Returns single word whose bits are the parities of buf[0], ...,
* buf[63]. Assumes 64-bit machine unsigned long.
*
* \param buf buffer of words of length 64
*/
static inline word parity64(word* buf)
{
word d0, d1, e0, e1;
d0 = _parity64_helper(buf);
d1 = _parity64_helper(buf + 2);
e0 = MIX2(d1, d0);
d0 = _parity64_helper(buf + 1);
d1 = _parity64_helper(buf + 3);
e1 = MIX2(d1, d0);
return MIX1(e1, e0);
}
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