Lines Matching +full:low +full:- +full:precision
3 /*-
4 * SPDX-License-Identifier: BSD-3-Clause
10 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
62 * (2^n) (u1 v0 - u1 v1 + u0 v1 - u0 v0) +
68 * (2^n) (u1 - u0) (v0 - v1) + [(u1-u0)... = mid]
69 * (2^n + 1) (u0 v0) [u0v0 = low]
71 * The terms (u1 v1), (u1 - u0) (v0 - v1), and (u0 v0) can all be done
72 * in just half the precision of the original. (Note that either or both
73 * of (u1 - u0) or (v0 - v1) may be negative.)
87 * (2^n)(high) + (2^n)(mid) + (2^n + 1)(low)
91 * (2^n)(high + mid + low) + low
94 * of 2^n in either one will also vanish. Only `low' need be computed
103 union uu u, v, low, prod; in __muldi3() local
119 u.q = -a, negall = 1; in __muldi3()
123 v.q = -b, negall ^= 1; in __muldi3()
139 low.q = __lmulq(u0, v0); in __muldi3()
142 negmid = 0, udiff = u1 - u0; in __muldi3()
144 negmid = 1, udiff = u0 - u1; in __muldi3()
146 vdiff = v0 - v1; in __muldi3()
148 vdiff = v1 - v0, negmid ^= 1; in __muldi3()
156 prod.ul[H] = high + (negmid ? -mid : mid) + low.ul[L] + in __muldi3()
157 low.ul[H]; in __muldi3()
158 prod.ul[L] = low.ul[L]; in __muldi3()
160 return (negall ? -prod.q : prod.q); in __muldi3()
168 * Multiply two 2N-bit ints to produce a 4N-bit quad, where N is half
169 * the number of bits in an int (whatever that is---the code below
170 * does not care as long as quad.h does its part of the bargain---but
175 * we can get away with native multiplication---none of our input terms
178 * Note that, for u_int l, the quad-precision result
182 * splits into high and low ints as HHALF(l) and LHUP(l) respectively.
187 u_int u1, u0, v1, v0, udiff, vdiff, high, mid, low; in __lmulq() local
197 low = u0 * v0; in __lmulq()
199 /* This is the same small-number optimization as before. */ in __lmulq()
201 return (low); in __lmulq()
204 udiff = u1 - u0, neg = 0; in __lmulq()
206 udiff = u0 - u1, neg = 1; in __lmulq()
208 vdiff = v0 - v1; in __lmulq()
210 vdiff = v1 - v0, neg ^= 1; in __lmulq()
219 /* if (neg) prod -= mid << N; else prod += mid << N; */ in __lmulq()
222 prodl -= LHUP(mid); in __lmulq()
223 prodh -= HHALF(mid) + (prodl > was); in __lmulq()
230 /* prod += low << N */ in __lmulq()
232 prodl += LHUP(low); in __lmulq()
233 prodh += HHALF(low) + (prodl < was); in __lmulq()
234 /* ... + low; */ in __lmulq()
235 if ((prodl += low) < low) in __lmulq()
238 /* return 4N-bit product */ in __lmulq()