diff options
Diffstat (limited to 'arch/mips/math-emu/dp_sub.c')
| -rw-r--r-- | arch/mips/math-emu/dp_sub.c | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/arch/mips/math-emu/dp_sub.c b/arch/mips/math-emu/dp_sub.c new file mode 100644 index 00000000000..b30c5b1f1a2 --- /dev/null +++ b/arch/mips/math-emu/dp_sub.c @@ -0,0 +1,191 @@ +/* IEEE754 floating point arithmetic + * double precision: common utilities + */ +/* + * MIPS floating point support + * Copyright (C) 1994-2000 Algorithmics Ltd. + * http://www.algor.co.uk + * + * ######################################################################## + * + * 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_sub(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(), "sub", 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(), "sub", x, y); + + case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF): + case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF): + case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF): + return ieee754dp_inf(ys ^ 1); + + 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): + /* quick fix up */ + DPSIGN(y) ^= 1; + return y; + + case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM): + DPDNORMX; + /* FAAL THOROUGH */ + + case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM): + /* normalize ym,ye */ + DPDNORMY; + break; + + case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM): + /* normalize xm,xe */ + DPDNORMX; + break; + + case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM): + break; + } + /* flip sign of y and handle as add */ + ys ^= 1; + + assert(xm & DP_HIDDEN_BIT); + assert(ym & DP_HIDDEN_BIT); + + + /* provide guard,round and stick bit dpace */ + 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 + */ + xm = xm + ym; + xe = xe; + xs = xs; + + if (xm >> (DP_MBITS + 1 + 3)) { /* carry out */ + xm = XDPSRS1(xm); /* shift preserving sticky */ + xe++; + } + } else { + if (xm >= ym) { + xm = xm - ym; + xe = xe; + xs = xs; + } else { + xm = ym - xm; + xe = xe; + xs = ys; + } + if (xm == 0) { + if (ieee754_csr.rm == IEEE754_RD) + return ieee754dp_zero(1); /* round negative inf. => sign = -1 */ + else + return ieee754dp_zero(0); /* other round modes => sign = 1 */ + } + + /* normalize to rounding precision + */ + while ((xm >> (DP_MBITS + 3)) == 0) { + xm <<= 1; + xe--; + } + } + DPNORMRET2(xs, xe, xm, "sub", x, y); +} |