| /* | |
| * 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); | |
| } |