/* * 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/dfmpy.c $Revision: 1.1 $ * * Purpose: * Double Precision Floating-point Multiply * * External Interfaces: * dbl_fmpy(srcptr1,srcptr2,dstptr,status) * * Internal Interfaces: * * Theory: * <<please update with a overview of the operation of this file>> * * END_DESC */ #include "float.h" #include "dbl_float.h" /* * Double Precision Floating-point Multiply */ int dbl_fmpy( dbl_floating_point *srcptr1, dbl_floating_point *srcptr2, dbl_floating_point *dstptr, unsigned int *status) { register unsigned int opnd1p1, opnd1p2, opnd2p1, opnd2p2; register unsigned int opnd3p1, opnd3p2, resultp1, resultp2; register int dest_exponent, count; register boolean inexact = FALSE, guardbit = FALSE, stickybit = FALSE; boolean is_tiny; Dbl_copyfromptr(srcptr1,opnd1p1,opnd1p2); Dbl_copyfromptr(srcptr2,opnd2p1,opnd2p2); /* * set sign bit of result */ if (Dbl_sign(opnd1p1) ^ Dbl_sign(opnd2p1)) Dbl_setnegativezerop1(resultp1); else Dbl_setzerop1(resultp1); /* * check first operand for NaN's or infinity */ if (Dbl_isinfinity_exponent(opnd1p1)) { if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) { if (Dbl_isnotnan(opnd2p1,opnd2p2)) { if (Dbl_iszero_exponentmantissa(opnd2p1,opnd2p2)) { /* * invalid since operands are infinity * and zero */ if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); Set_invalidflag(); Dbl_makequietnan(resultp1,resultp2); Dbl_copytoptr(resultp1,resultp2,dstptr); return(NOEXCEPTION); } /* * return infinity */ Dbl_setinfinity_exponentmantissa(resultp1,resultp2); Dbl_copytoptr(resultp1,resultp2,dstptr); return(NOEXCEPTION); } } else { /* * is NaN; signaling or quiet? */ if (Dbl_isone_signaling(opnd1p1)) { /* trap if INVALIDTRAP enabled */ if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); /* make NaN quiet */ Set_invalidflag(); Dbl_set_quiet(opnd1p1); } /* * is second operand a signaling NaN? */ else if (Dbl_is_signalingnan(opnd2p1)) { /* trap if INVALIDTRAP enabled */ if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); /* make NaN quiet */ Set_invalidflag(); Dbl_set_quiet(opnd2p1); Dbl_copytoptr(opnd2p1,opnd2p2,dstptr); return(NOEXCEPTION); } /* * return quiet NaN */ Dbl_copytoptr(opnd1p1,opnd1p2,dstptr); return(NOEXCEPTION); } } /* * check second operand for NaN's or infinity */ if (Dbl_isinfinity_exponent(opnd2p1)) { if (Dbl_iszero_mantissa(opnd2p1,opnd2p2)) { if (Dbl_iszero_exponentmantissa(opnd1p1,opnd1p2)) { /* invalid since operands are zero & infinity */ if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); Set_invalidflag(); Dbl_makequietnan(opnd2p1,opnd2p2); Dbl_copytoptr(opnd2p1,opnd2p2,dstptr); return(NOEXCEPTION); } /* * return infinity */ Dbl_setinfinity_exponentmantissa(resultp1,resultp2); Dbl_copytoptr(resultp1,resultp2,dstptr); return(NOEXCEPTION); } /* * is NaN; signaling or quiet? */ if (Dbl_isone_signaling(opnd2p1)) { /* trap if INVALIDTRAP enabled */ if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); /* make NaN quiet */ Set_invalidflag(); Dbl_set_quiet(opnd2p1); } /* * return quiet NaN */ Dbl_copytoptr(opnd2p1,opnd2p2,dstptr); return(NOEXCEPTION); } /* * Generate exponent */ dest_exponent = Dbl_exponent(opnd1p1) + Dbl_exponent(opnd2p1) -DBL_BIAS; /* * Generate mantissa */ if (Dbl_isnotzero_exponent(opnd1p1)) { /* set hidden bit */ Dbl_clear_signexponent_set_hidden(opnd1p1); } else { /* check for zero */ if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) { Dbl_setzero_exponentmantissa(resultp1,resultp2); Dbl_copytoptr(resultp1,resultp2,dstptr); return(NOEXCEPTION); } /* is denormalized, adjust exponent */ Dbl_clear_signexponent(opnd1p1); Dbl_leftshiftby1(opnd1p1,opnd1p2); Dbl_normalize(opnd1p1,opnd1p2,dest_exponent); } /* opnd2 needs to have hidden bit set with msb in hidden bit */ if (Dbl_isnotzero_exponent(opnd2p1)) { Dbl_clear_signexponent_set_hidden(opnd2p1); } else { /* check for zero */ if (Dbl_iszero_mantissa(opnd2p1,opnd2p2)) { Dbl_setzero_exponentmantissa(resultp1,resultp2); Dbl_copytoptr(resultp1,resultp2,dstptr); return(NOEXCEPTION); } /* is denormalized; want to normalize */ Dbl_clear_signexponent(opnd2p1); Dbl_leftshiftby1(opnd2p1,opnd2p2); Dbl_normalize(opnd2p1,opnd2p2,dest_exponent); } /* Multiply two source mantissas together */ /* make room for guard bits */ Dbl_leftshiftby7(opnd2p1,opnd2p2); Dbl_setzero(opnd3p1,opnd3p2); /* * Four bits at a time are inspected in each loop, and a * simple shift and add multiply algorithm is used. */ for (count=1;count<=DBL_P;count+=4) { stickybit |= Dlow4p2(opnd3p2); Dbl_rightshiftby4(opnd3p1,opnd3p2); if (Dbit28p2(opnd1p2)) { /* Twoword_add should be an ADDC followed by an ADD. */ Twoword_add(opnd3p1, opnd3p2, opnd2p1<<3 | opnd2p2>>29, opnd2p2<<3); } if (Dbit29p2(opnd1p2)) { Twoword_add(opnd3p1, opnd3p2, opnd2p1<<2 | opnd2p2>>30, opnd2p2<<2); } if (Dbit30p2(opnd1p2)) { Twoword_add(opnd3p1, opnd3p2, opnd2p1<<1 | opnd2p2>>31, opnd2p2<<1); } if (Dbit31p2(opnd1p2)) { Twoword_add(opnd3p1, opnd3p2, opnd2p1, opnd2p2); } Dbl_rightshiftby4(opnd1p1,opnd1p2); } if (Dbit3p1(opnd3p1)==0) { Dbl_leftshiftby1(opnd3p1,opnd3p2); } else { /* result mantissa >= 2. */ dest_exponent++; } /* check for denormalized result */ while (Dbit3p1(opnd3p1)==0) { Dbl_leftshiftby1(opnd3p1,opnd3p2); dest_exponent--; } /* * check for guard, sticky and inexact bits */ stickybit |= Dallp2(opnd3p2) << 25; guardbit = (Dallp2(opnd3p2) << 24) >> 31; inexact = guardbit | stickybit; /* align result mantissa */ Dbl_rightshiftby8(opnd3p1,opnd3p2); /* * round result */ if (inexact && (dest_exponent>0 || Is_underflowtrap_enabled())) { Dbl_clear_signexponent(opnd3p1); switch (Rounding_mode()) { case ROUNDPLUS: if (Dbl_iszero_sign(resultp1)) Dbl_increment(opnd3p1,opnd3p2); break; case ROUNDMINUS: if (Dbl_isone_sign(resultp1)) Dbl_increment(opnd3p1,opnd3p2); break; case ROUNDNEAREST: if (guardbit) { if (stickybit || Dbl_isone_lowmantissap2(opnd3p2)) Dbl_increment(opnd3p1,opnd3p2); } } if (Dbl_isone_hidden(opnd3p1)) dest_exponent++; } Dbl_set_mantissa(resultp1,resultp2,opnd3p1,opnd3p2); /* * Test for overflow */ if (dest_exponent >= DBL_INFINITY_EXPONENT) { /* trap if OVERFLOWTRAP enabled */ if (Is_overflowtrap_enabled()) { /* * Adjust bias of result */ Dbl_setwrapped_exponent(resultp1,dest_exponent,ovfl); Dbl_copytoptr(resultp1,resultp2,dstptr); if (inexact) if (Is_inexacttrap_enabled()) return (OVERFLOWEXCEPTION | INEXACTEXCEPTION); else Set_inexactflag(); return (OVERFLOWEXCEPTION); } inexact = TRUE; Set_overflowflag(); /* set result to infinity or largest number */ Dbl_setoverflow(resultp1,resultp2); } /* * Test for underflow */ else if (dest_exponent <= 0) { /* trap if UNDERFLOWTRAP enabled */ if (Is_underflowtrap_enabled()) { /* * Adjust bias of result */ Dbl_setwrapped_exponent(resultp1,dest_exponent,unfl); Dbl_copytoptr(resultp1,resultp2,dstptr); if (inexact) if (Is_inexacttrap_enabled()) return (UNDERFLOWEXCEPTION | INEXACTEXCEPTION); else Set_inexactflag(); return (UNDERFLOWEXCEPTION); } /* Determine if should set underflow flag */ is_tiny = TRUE; if (dest_exponent == 0 && inexact) { switch (Rounding_mode()) { case ROUNDPLUS: if (Dbl_iszero_sign(resultp1)) { Dbl_increment(opnd3p1,opnd3p2); if (Dbl_isone_hiddenoverflow(opnd3p1)) is_tiny = FALSE; Dbl_decrement(opnd3p1,opnd3p2); } break; case ROUNDMINUS: if (Dbl_isone_sign(resultp1)) { Dbl_increment(opnd3p1,opnd3p2); if (Dbl_isone_hiddenoverflow(opnd3p1)) is_tiny = FALSE; Dbl_decrement(opnd3p1,opnd3p2); } break; case ROUNDNEAREST: if (guardbit && (stickybit || Dbl_isone_lowmantissap2(opnd3p2))) { Dbl_increment(opnd3p1,opnd3p2); if (Dbl_isone_hiddenoverflow(opnd3p1)) is_tiny = FALSE; Dbl_decrement(opnd3p1,opnd3p2); } break; } } /* * denormalize result or set to signed zero */ stickybit = inexact; Dbl_denormalize(opnd3p1,opnd3p2,dest_exponent,guardbit, stickybit,inexact); /* return zero or smallest number */ if (inexact) { switch (Rounding_mode()) { case ROUNDPLUS: if (Dbl_iszero_sign(resultp1)) { Dbl_increment(opnd3p1,opnd3p2); } break; case ROUNDMINUS: if (Dbl_isone_sign(resultp1)) { Dbl_increment(opnd3p1,opnd3p2); } break; case ROUNDNEAREST: if (guardbit && (stickybit || Dbl_isone_lowmantissap2(opnd3p2))) { Dbl_increment(opnd3p1,opnd3p2); } break; } if (is_tiny) Set_underflowflag(); } Dbl_set_exponentmantissa(resultp1,resultp2,opnd3p1,opnd3p2); } else Dbl_set_exponent(resultp1,dest_exponent); /* check for inexact */ Dbl_copytoptr(resultp1,resultp2,dstptr); if (inexact) { if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION); else Set_inexactflag(); } return(NOEXCEPTION); }