Lines Matching +full:quad +full:- +full:precision

1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
8  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
36 #include "quad.h"
41  * Our algorithm is based on the following.  Split incoming quad values
60  *	         (2^n)    (u1 v0 - u1 v1 + u0 v1 - u0 v0)  +
66  *		 (2^n)    (u1 - u0) (v0 - v1)  +	[(u1-u0)... = mid]
69  * The terms (u1 v1), (u1 - u0) (v0 - v1), and (u0 v0) can all be done
70  * in just half the precision of the original.  (Note that either or both
71  * of (u1 - u0) or (v0 - v1) may be negative.)
75  * Since C does not give us a `long * long = quad' operator, we split
80  * Our product should, strictly speaking, be a `long quad', with 128
116 		u.q = -a, negall = 1;  in __muldi3()
120 		v.q = -b, negall ^= 1;  in __muldi3()
139 			negmid = 0, udiff = u1 - u0;  in __muldi3()
141 			negmid = 1, udiff = u0 - u1;  in __muldi3()
143 			vdiff = v0 - v1;  in __muldi3()
145 			vdiff = v1 - v0, negmid ^= 1;  in __muldi3()
153 		prod.ul[H] = high + (negmid ? -mid : mid) + low.ul[L] +  in __muldi3()
157 	return (negall ? -prod.q : prod.q);  in __muldi3()
165  * Multiply two 2N-bit longs to produce a 4N-bit quad, where N is half
166  * the number of bits in a long (whatever that is---the code below
167  * does not care as long as quad.h does its part of the bargain---but
172  * we can get away with native multiplication---none of our input terms
175  * Note that, for u_long l, the quad-precision result
196 	/* This is the same small-number optimization as before. */  in __lmulq()
201 		udiff = u1 - u0, neg = 0;  in __lmulq()
203 		udiff = u0 - u1, neg = 1;  in __lmulq()
205 		vdiff = v0 - v1;  in __lmulq()
207 		vdiff = v1 - v0, neg ^= 1;  in __lmulq()
216 	/* if (neg) prod -= mid << N; else prod += mid << N; */  in __lmulq()
219 		prodl -= LHUP(mid);  in __lmulq()
220 		prodh -= HHALF(mid) + (prodl > was);  in __lmulq()
235 	/* return 4N-bit product */  in __lmulq()