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#include "rt_def.h"
#include "rt_sqrt.h"
/*
C version of fixed-point Square Root functions
*/
long FixedSqrtLP(long n) // Low Precision (8.8)
{
/*
Not used, so unimplemented.
If it matters, just copy the first half of the HP version,
and multiply the answer by 256.
*/
STUB_FUNCTION;
return 0;
}
long FixedSqrtHP(long n) // High Precision (8.16)
{
/* This is more or less a direct C transliteration of the asm code.
I've replaced right shifting with division, since right shifting
signed values is undefined in ANSI C (though it usually works).
ROTT does not use this routine heavily. */
unsigned long root, mask, val;
signed long d;
root = 0;
mask = 0x40000000;
val = (unsigned long)n;
hp1:
d = val;
d -= mask;
if (d < 0)
goto hp2;
d -= root;
if (d < 0)
goto hp2;
val = d;
root /= 2;
root |= mask;
mask /= 4;
if (mask != 0)
goto hp1;
else
goto hp5;
hp2:
root /= 2;
mask /= 4;
if (mask != 0)
goto hp1;
hp5:
mask = 0x00004000;
root <<= 16;
val <<= 16;
hp3:
/* use add here to properly emulate the asm - SBF */
if ((root+mask) > val)
goto hp4;
val -= (root+mask);
root /= 2;
root |= mask;
mask /= 4;
if (mask != 0)
goto hp3;
else
goto hp6;
hp4:
root /= 2;
mask /= 4;
if (mask != 0)
goto hp3;
hp6:
return (long)root;
}
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