dp_add.rar_floating

/* IEEE754 floating point arithmetic * double precision: common utilities */ /* * MIPS floating point support * * * ######################################################################## * * 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_add(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(), "add", 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): if (xs == ys) return x; SETCX(IEEE754_INVALID_OPERATION); return ieee754dp_xcpt(ieee754dp_indef(), "add", 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 y; 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 x; /* Zero handling */ case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO): if (xs == ys) return x; else return ieee754dp_zero(ieee754_csr.rm == IEEE754_RD); case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO): case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO): return x; case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM): case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM): return y; case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM): DPDNORMX; /* FALL THROUGH */ 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 guard,round and stick bit space */ xm <<= 3; ym <<= 3; if (xe > ye) { /* have to shift y fraction right to align */ int s = xe - ye; ym = XDPSRS(ym, s); ye += s; } else if (ye > xe) { /* have to shift x fraction right to align */ int s = ye - xe; xm = XDPSRS(xm, s); xe += s; } assert(xe == ye); assert(xe <= DP_EMAX); if (xs == ys) { /* generate 28 bit result of adding two 27 bit numbers * leaving result in xm,xs,xe */ xm = xm + ym; xe = xe; xs = xs; if (xm >> (DP_MBITS + 1 + 3)) { /* carry out */ xm = XDPSRS1(xm); xe++; } } else { if (xm >= ym) { xm = xm - ym; xe = xe; xs = xs; } else { xm = ym - xm; xe = xe; xs = ys; } if (xm == 0) return ieee754dp_zero(ieee754_csr.rm == IEEE754_RD); /* normalize to rounding precision */ while ((xm >> (DP_MBITS + 3)) == 0) { xm <<= 1; xe--; } } DPNORMRET2(xs, xe, xm, "add", x, y); }