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Diffstat (limited to 'arch/mips/math-emu/ieee754dp.c')
| -rw-r--r-- | arch/mips/math-emu/ieee754dp.c | 243 |
1 files changed, 243 insertions, 0 deletions
diff --git a/arch/mips/math-emu/ieee754dp.c b/arch/mips/math-emu/ieee754dp.c new file mode 100644 index 0000000..3e214aa --- /dev/null +++ b/arch/mips/math-emu/ieee754dp.c @@ -0,0 +1,243 @@ +/* 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" + +int ieee754dp_class(ieee754dp x) +{ + COMPXDP; + EXPLODEXDP; + return xc; +} + +int ieee754dp_isnan(ieee754dp x) +{ + return ieee754dp_class(x) >= IEEE754_CLASS_SNAN; +} + +int ieee754dp_issnan(ieee754dp x) +{ + assert(ieee754dp_isnan(x)); + return ((DPMANT(x) & DP_MBIT(DP_MBITS-1)) == DP_MBIT(DP_MBITS-1)); +} + + +ieee754dp ieee754dp_xcpt(ieee754dp r, const char *op, ...) +{ + struct ieee754xctx ax; + if (!TSTX()) + return r; + + ax.op = op; + ax.rt = IEEE754_RT_DP; + ax.rv.dp = r; + va_start(ax.ap, op); + ieee754_xcpt(&ax); + return ax.rv.dp; +} + +ieee754dp ieee754dp_nanxcpt(ieee754dp r, const char *op, ...) +{ + struct ieee754xctx ax; + + assert(ieee754dp_isnan(r)); + + if (!ieee754dp_issnan(r)) /* QNAN does not cause invalid op !! */ + return r; + + if (!SETANDTESTCX(IEEE754_INVALID_OPERATION)) { + /* not enabled convert to a quiet NaN */ + DPMANT(r) &= (~DP_MBIT(DP_MBITS-1)); + if (ieee754dp_isnan(r)) + return r; + else + return ieee754dp_indef(); + } + + ax.op = op; + ax.rt = 0; + ax.rv.dp = r; + va_start(ax.ap, op); + ieee754_xcpt(&ax); + return ax.rv.dp; +} + +ieee754dp ieee754dp_bestnan(ieee754dp x, ieee754dp y) +{ + assert(ieee754dp_isnan(x)); + assert(ieee754dp_isnan(y)); + + if (DPMANT(x) > DPMANT(y)) + return x; + else + return y; +} + + +static u64 get_rounding(int sn, u64 xm) +{ + /* inexact must round of 3 bits + */ + if (xm & (DP_MBIT(3) - 1)) { + switch (ieee754_csr.rm) { + case IEEE754_RZ: + break; + case IEEE754_RN: + xm += 0x3 + ((xm >> 3) & 1); + /* xm += (xm&0x8)?0x4:0x3 */ + break; + case IEEE754_RU: /* toward +Infinity */ + if (!sn) /* ?? */ + xm += 0x8; + break; + case IEEE754_RD: /* toward -Infinity */ + if (sn) /* ?? */ + xm += 0x8; + break; + } + } + return xm; +} + + +/* generate a normal/denormal number with over,under handling + * sn is sign + * xe is an unbiased exponent + * xm is 3bit extended precision value. + */ +ieee754dp ieee754dp_format(int sn, int xe, u64 xm) +{ + assert(xm); /* we don't gen exact zeros (probably should) */ + + assert((xm >> (DP_MBITS + 1 + 3)) == 0); /* no execess */ + assert(xm & (DP_HIDDEN_BIT << 3)); + + if (xe < DP_EMIN) { + /* strip lower bits */ + int es = DP_EMIN - xe; + + if (ieee754_csr.nod) { + SETCX(IEEE754_UNDERFLOW); + SETCX(IEEE754_INEXACT); + + switch(ieee754_csr.rm) { + case IEEE754_RN: + return ieee754dp_zero(sn); + case IEEE754_RZ: + return ieee754dp_zero(sn); + case IEEE754_RU: /* toward +Infinity */ + if(sn == 0) + return ieee754dp_min(0); + else + return ieee754dp_zero(1); + case IEEE754_RD: /* toward -Infinity */ + if(sn == 0) + return ieee754dp_zero(0); + else + return ieee754dp_min(1); + } + } + + if (xe == DP_EMIN - 1 + && get_rounding(sn, xm) >> (DP_MBITS + 1 + 3)) + { + /* Not tiny after rounding */ + SETCX(IEEE754_INEXACT); + xm = get_rounding(sn, xm); + xm >>= 1; + /* Clear grs bits */ + xm &= ~(DP_MBIT(3) - 1); + xe++; + } + else { + /* sticky right shift es bits + */ + xm = XDPSRS(xm, es); + xe += es; + assert((xm & (DP_HIDDEN_BIT << 3)) == 0); + assert(xe == DP_EMIN); + } + } + if (xm & (DP_MBIT(3) - 1)) { + SETCX(IEEE754_INEXACT); + if ((xm & (DP_HIDDEN_BIT << 3)) == 0) { + SETCX(IEEE754_UNDERFLOW); + } + + /* inexact must round of 3 bits + */ + xm = get_rounding(sn, xm); + /* adjust exponent for rounding add overflowing + */ + if (xm >> (DP_MBITS + 3 + 1)) { + /* add causes mantissa overflow */ + xm >>= 1; + xe++; + } + } + /* strip grs bits */ + xm >>= 3; + + assert((xm >> (DP_MBITS + 1)) == 0); /* no execess */ + assert(xe >= DP_EMIN); + + if (xe > DP_EMAX) { + SETCX(IEEE754_OVERFLOW); + SETCX(IEEE754_INEXACT); + /* -O can be table indexed by (rm,sn) */ + switch (ieee754_csr.rm) { + case IEEE754_RN: + return ieee754dp_inf(sn); + case IEEE754_RZ: + return ieee754dp_max(sn); + case IEEE754_RU: /* toward +Infinity */ + if (sn == 0) + return ieee754dp_inf(0); + else + return ieee754dp_max(1); + case IEEE754_RD: /* toward -Infinity */ + if (sn == 0) + return ieee754dp_max(0); + else + return ieee754dp_inf(1); + } + } + /* gen norm/denorm/zero */ + + if ((xm & DP_HIDDEN_BIT) == 0) { + /* we underflow (tiny/zero) */ + assert(xe == DP_EMIN); + if (ieee754_csr.mx & IEEE754_UNDERFLOW) + SETCX(IEEE754_UNDERFLOW); + return builddp(sn, DP_EMIN - 1 + DP_EBIAS, xm); + } else { + assert((xm >> (DP_MBITS + 1)) == 0); /* no execess */ + assert(xm & DP_HIDDEN_BIT); + + return builddp(sn, xe + DP_EBIAS, xm & ~DP_HIDDEN_BIT); + } +} |
