33 lines
729 B
C
33 lines
729 B
C
/*
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(c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands.
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See the copyright notice in the ACK home directory, in the file "Copyright".
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*/
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/* $Header$ */
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/*
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SUBTRACT TWO FLOATS - DOUBLE Precision (SBF 8)
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*/
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#include "FP_types.h"
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extern _double adf8();
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_double
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sbf8(s2,s1)
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_double s1,s2;
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{
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/* changing the sign directly */
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/* is faster than the code line */
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/* s2 = -s2; */
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char unsigned *p; /* sufficient to access sign bit */
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_double *result = &s1; /* s1 may not be in a register! */
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if (s2.__double[0] == 0 && s2.__double[1] == 0) {
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return s1;
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}
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p = (char unsigned *) &s2;
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*p ^= 0x80; /* change sign of s2 */
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*result = adf8(s2,s1); /* add and return result */
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return(s1);
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}
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