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Diffstat (limited to 'arch/parisc/math-emu/sfsqrt.c')
| -rw-r--r-- | arch/parisc/math-emu/sfsqrt.c | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/arch/parisc/math-emu/sfsqrt.c b/arch/parisc/math-emu/sfsqrt.c new file mode 100644 index 000000000..4657a12c9 --- /dev/null +++ b/arch/parisc/math-emu/sfsqrt.c @@ -0,0 +1,187 @@ +/* + * Linux/PA-RISC Project (http://www.parisc-linux.org/) + * + * Floating-point emulation code + * Copyright (C) 2001 Hewlett-Packard (Paul Bame) <bame@debian.org> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2, or (at your option) + * any later version. + * + * This program is distributed in the hope that 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 + */ +/* + * BEGIN_DESC + * + * File: + * @(#) pa/spmath/sfsqrt.c $Revision: 1.1 $ + * + * Purpose: + * Single Floating-point Square Root + * + * External Interfaces: + * sgl_fsqrt(srcptr,nullptr,dstptr,status) + * + * Internal Interfaces: + * + * Theory: + * <<please update with a overview of the operation of this file>> + * + * END_DESC +*/ + + +#include "float.h" +#include "sgl_float.h" + +/* + * Single Floating-point Square Root + */ + +/*ARGSUSED*/ +unsigned int +sgl_fsqrt( + sgl_floating_point *srcptr, + unsigned int *nullptr, + sgl_floating_point *dstptr, + unsigned int *status) +{ + register unsigned int src, result; + register int src_exponent; + register unsigned int newbit, sum; + register boolean guardbit = FALSE, even_exponent; + + src = *srcptr; + /* + * check source operand for NaN or infinity + */ + if ((src_exponent = Sgl_exponent(src)) == SGL_INFINITY_EXPONENT) { + /* + * is signaling NaN? + */ + if (Sgl_isone_signaling(src)) { + /* trap if INVALIDTRAP enabled */ + if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); + /* make NaN quiet */ + Set_invalidflag(); + Sgl_set_quiet(src); + } + /* + * Return quiet NaN or positive infinity. + * Fall through to negative test if negative infinity. + */ + if (Sgl_iszero_sign(src) || Sgl_isnotzero_mantissa(src)) { + *dstptr = src; + return(NOEXCEPTION); + } + } + + /* + * check for zero source operand + */ + if (Sgl_iszero_exponentmantissa(src)) { + *dstptr = src; + return(NOEXCEPTION); + } + + /* + * check for negative source operand + */ + if (Sgl_isone_sign(src)) { + /* trap if INVALIDTRAP enabled */ + if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); + /* make NaN quiet */ + Set_invalidflag(); + Sgl_makequietnan(src); + *dstptr = src; + return(NOEXCEPTION); + } + + /* + * Generate result + */ + if (src_exponent > 0) { + even_exponent = Sgl_hidden(src); + Sgl_clear_signexponent_set_hidden(src); + } + else { + /* normalize operand */ + Sgl_clear_signexponent(src); + src_exponent++; + Sgl_normalize(src,src_exponent); + even_exponent = src_exponent & 1; + } + if (even_exponent) { + /* exponent is even */ + /* Add comment here. Explain why odd exponent needs correction */ + Sgl_leftshiftby1(src); + } + /* + * Add comment here. Explain following algorithm. + * + * Trust me, it works. + * + */ + Sgl_setzero(result); + newbit = 1 << SGL_P; + while (newbit && Sgl_isnotzero(src)) { + Sgl_addition(result,newbit,sum); + if(sum <= Sgl_all(src)) { + /* update result */ + Sgl_addition(result,(newbit<<1),result); + Sgl_subtract(src,sum,src); + } + Sgl_rightshiftby1(newbit); + Sgl_leftshiftby1(src); + } + /* correct exponent for pre-shift */ + if (even_exponent) { + Sgl_rightshiftby1(result); + } + + /* check for inexact */ + if (Sgl_isnotzero(src)) { + if (!even_exponent && Sgl_islessthan(result,src)) + Sgl_increment(result); + guardbit = Sgl_lowmantissa(result); + Sgl_rightshiftby1(result); + + /* now round result */ + switch (Rounding_mode()) { + case ROUNDPLUS: + Sgl_increment(result); + break; + case ROUNDNEAREST: + /* stickybit is always true, so guardbit + * is enough to determine rounding */ + if (guardbit) { + Sgl_increment(result); + } + break; + } + /* increment result exponent by 1 if mantissa overflowed */ + if (Sgl_isone_hiddenoverflow(result)) src_exponent+=2; + + if (Is_inexacttrap_enabled()) { + Sgl_set_exponent(result, + ((src_exponent-SGL_BIAS)>>1)+SGL_BIAS); + *dstptr = result; + return(INEXACTEXCEPTION); + } + else Set_inexactflag(); + } + else { + Sgl_rightshiftby1(result); + } + Sgl_set_exponent(result,((src_exponent-SGL_BIAS)>>1)+SGL_BIAS); + *dstptr = result; + return(NOEXCEPTION); +} |