/* IEEE754 floating point arithmetic * double precision: common utilities */ /* * MIPS floating point support * Copyright (C) 1994-2000 Algorithmics Ltd. * * ######################################################################## * * This program is free software; you can distribute it and/or modify it * under the terms of the GNU General Public License (Version 2) as * published by the Free Software Foundation. * * This program is distributed in the hope it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * for more details. * * You should have received a copy of the GNU General Public License along * with this program; if not, write to the Free Software Foundation, Inc., * 59 Temple Place - Suite 330, Boston MA 02111-1307, USA. * * ######################################################################## */ #include "ieee754dp.h" ieee754dp ieee754dp_div(ieee754dp x, ieee754dp y) { COMPXDP; COMPYDP; EXPLODEXDP; EXPLODEYDP; CLEARCX; FLUSHXDP; FLUSHYDP; switch (CLPAIR(xc, yc)) { case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN): case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN): case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN): case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN): case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN): case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN): case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN): case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO): case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM): case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM): case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF): SETCX(IEEE754_INVALID_OPERATION); return ieee754dp_nanxcpt(ieee754dp_indef(), "div", x, y); case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN): case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN): case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN): case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN): return y; case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN): case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO): case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM): case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM): case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF): return x; /* Infinity handling */ case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF): SETCX(IEEE754_INVALID_OPERATION); return ieee754dp_xcpt(ieee754dp_indef(), "div", x, y); case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF): case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF): case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF): return ieee754dp_zero(xs ^ ys); case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO): case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM): case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM): return ieee754dp_inf(xs ^ ys); /* Zero handling */ case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO): SETCX(IEEE754_INVALID_OPERATION); return ieee754dp_xcpt(ieee754dp_indef(), "div", x, y); case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO): case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO): SETCX(IEEE754_ZERO_DIVIDE); return ieee754dp_xcpt(ieee754dp_inf(xs ^ ys), "div", x, y); case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM): case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM): return ieee754dp_zero(xs == ys ? 0 : 1); case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM): DPDNORMX; case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM): DPDNORMY; break; case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM): DPDNORMX; break; case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM): break; } assert(xm & DP_HIDDEN_BIT); assert(ym & DP_HIDDEN_BIT); /* provide rounding space */ xm <<= 3; ym <<= 3; { /* now the dirty work */ u64 rm = 0; int re = xe - ye; u64 bm; for (bm = DP_MBIT(DP_MBITS + 2); bm; bm >>= 1) { if (xm >= ym) { xm -= ym; rm |= bm; if (xm == 0) break; } xm <<= 1; } rm <<= 1; if (xm) rm |= 1; /* have remainder, set sticky */ assert(rm); /* normalise rm to rounding precision ? */ while ((rm >> (DP_MBITS + 3)) == 0) { rm <<= 1; re--; } DPNORMRET2(xs == ys ? 0 : 1, re, rm, "div", x, y); } }