Trailing-Edge
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PDP-10 Archives
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SRI_NIC_PERM_FS_1_19910112
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kcc-6/lib/math/sign.c
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/*
* +++ NAME +++
*
* SIGN Transfer of sign
*
* +++ INDEX +++
*
* SIGN
* machine independent routines
* math libraries
*
* +++ DESCRIPTION +++
*
* Returns first argument with same sign as second argument.
*
* +++ USAGE +++
*
* double _sign(x, y)
* double x, y;
*
* +++ PROGRAMMER +++
*
* Fred Fish
* Goodyear Aerospace Corp, Arizona Div.
* (602) 932-7000 work
* (602) 894-6881 home
*
* Modifications for inclusion in standard C library are
* (c) Copyright Ian Macky, SRI International 1985
* Additional modifications after v.3, 18-May-1987 are
* (c) Copyright Ken Harrenstien 1989
*
*/
#include <c-env.h>
double _sign(x, y)
double x, y;
{
#if CPU_PDP10
#asm
DMOVE 1,-2(17) /* Get 1st double arg (X) */
MOVE 3,1
XOR 3,-4(17) /* XOR the sign bit with 2nd double arg */
CAIL 3, /* Test result */
POPJ 17, /* Bits same, just return X */
DMOVN 1,1 /* Different, so negate X */
#endasm
#else
if (x > 0.0) {
if (y > 0.0)
return x;
else
return -x;
} else {
if (y < 0.0)
return x;
else
return -x;
}
#endif
}