| /* | |
| * 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/sfdiv.c $Revision: 1.1 $ | |
| * | |
| * Purpose: | |
| * Single Precision Floating-point Divide | |
| * | |
| * External Interfaces: | |
| * sgl_fdiv(srcptr1,srcptr2,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 Precision Floating-point Divide | |
| */ | |
| int | |
| sgl_fdiv (sgl_floating_point * srcptr1, sgl_floating_point * srcptr2, | |
| sgl_floating_point * dstptr, unsigned int *status) | |
| { | |
| register unsigned int opnd1, opnd2, opnd3, result; | |
| register int dest_exponent, count; | |
| register boolean inexact = FALSE, guardbit = FALSE, stickybit = FALSE; | |
| boolean is_tiny; | |
| opnd1 = *srcptr1; | |
| opnd2 = *srcptr2; | |
| /* | |
| * set sign bit of result | |
| */ | |
| if (Sgl_sign(opnd1) ^ Sgl_sign(opnd2)) Sgl_setnegativezero(result); | |
| else Sgl_setzero(result); | |
| /* | |
| * check first operand for NaN's or infinity | |
| */ | |
| if (Sgl_isinfinity_exponent(opnd1)) { | |
| if (Sgl_iszero_mantissa(opnd1)) { | |
| if (Sgl_isnotnan(opnd2)) { | |
| if (Sgl_isinfinity(opnd2)) { | |
| /* | |
| * invalid since both operands | |
| * are infinity | |
| */ | |
| if (Is_invalidtrap_enabled()) | |
| return(INVALIDEXCEPTION); | |
| Set_invalidflag(); | |
| Sgl_makequietnan(result); | |
| *dstptr = result; | |
| return(NOEXCEPTION); | |
| } | |
| /* | |
| * return infinity | |
| */ | |
| Sgl_setinfinity_exponentmantissa(result); | |
| *dstptr = result; | |
| return(NOEXCEPTION); | |
| } | |
| } | |
| else { | |
| /* | |
| * is NaN; signaling or quiet? | |
| */ | |
| if (Sgl_isone_signaling(opnd1)) { | |
| /* trap if INVALIDTRAP enabled */ | |
| if (Is_invalidtrap_enabled()) | |
| return(INVALIDEXCEPTION); | |
| /* make NaN quiet */ | |
| Set_invalidflag(); | |
| Sgl_set_quiet(opnd1); | |
| } | |
| /* | |
| * is second operand a signaling NaN? | |
| */ | |
| else if (Sgl_is_signalingnan(opnd2)) { | |
| /* trap if INVALIDTRAP enabled */ | |
| if (Is_invalidtrap_enabled()) | |
| return(INVALIDEXCEPTION); | |
| /* make NaN quiet */ | |
| Set_invalidflag(); | |
| Sgl_set_quiet(opnd2); | |
| *dstptr = opnd2; | |
| return(NOEXCEPTION); | |
| } | |
| /* | |
| * return quiet NaN | |
| */ | |
| *dstptr = opnd1; | |
| return(NOEXCEPTION); | |
| } | |
| } | |
| /* | |
| * check second operand for NaN's or infinity | |
| */ | |
| if (Sgl_isinfinity_exponent(opnd2)) { | |
| if (Sgl_iszero_mantissa(opnd2)) { | |
| /* | |
| * return zero | |
| */ | |
| Sgl_setzero_exponentmantissa(result); | |
| *dstptr = result; | |
| return(NOEXCEPTION); | |
| } | |
| /* | |
| * is NaN; signaling or quiet? | |
| */ | |
| if (Sgl_isone_signaling(opnd2)) { | |
| /* trap if INVALIDTRAP enabled */ | |
| if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); | |
| /* make NaN quiet */ | |
| Set_invalidflag(); | |
| Sgl_set_quiet(opnd2); | |
| } | |
| /* | |
| * return quiet NaN | |
| */ | |
| *dstptr = opnd2; | |
| return(NOEXCEPTION); | |
| } | |
| /* | |
| * check for division by zero | |
| */ | |
| if (Sgl_iszero_exponentmantissa(opnd2)) { | |
| if (Sgl_iszero_exponentmantissa(opnd1)) { | |
| /* invalid since both operands are zero */ | |
| if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); | |
| Set_invalidflag(); | |
| Sgl_makequietnan(result); | |
| *dstptr = result; | |
| return(NOEXCEPTION); | |
| } | |
| if (Is_divisionbyzerotrap_enabled()) | |
| return(DIVISIONBYZEROEXCEPTION); | |
| Set_divisionbyzeroflag(); | |
| Sgl_setinfinity_exponentmantissa(result); | |
| *dstptr = result; | |
| return(NOEXCEPTION); | |
| } | |
| /* | |
| * Generate exponent | |
| */ | |
| dest_exponent = Sgl_exponent(opnd1) - Sgl_exponent(opnd2) + SGL_BIAS; | |
| /* | |
| * Generate mantissa | |
| */ | |
| if (Sgl_isnotzero_exponent(opnd1)) { | |
| /* set hidden bit */ | |
| Sgl_clear_signexponent_set_hidden(opnd1); | |
| } | |
| else { | |
| /* check for zero */ | |
| if (Sgl_iszero_mantissa(opnd1)) { | |
| Sgl_setzero_exponentmantissa(result); | |
| *dstptr = result; | |
| return(NOEXCEPTION); | |
| } | |
| /* is denormalized; want to normalize */ | |
| Sgl_clear_signexponent(opnd1); | |
| Sgl_leftshiftby1(opnd1); | |
| Sgl_normalize(opnd1,dest_exponent); | |
| } | |
| /* opnd2 needs to have hidden bit set with msb in hidden bit */ | |
| if (Sgl_isnotzero_exponent(opnd2)) { | |
| Sgl_clear_signexponent_set_hidden(opnd2); | |
| } | |
| else { | |
| /* is denormalized; want to normalize */ | |
| Sgl_clear_signexponent(opnd2); | |
| Sgl_leftshiftby1(opnd2); | |
| while(Sgl_iszero_hiddenhigh7mantissa(opnd2)) { | |
| Sgl_leftshiftby8(opnd2); | |
| dest_exponent += 8; | |
| } | |
| if(Sgl_iszero_hiddenhigh3mantissa(opnd2)) { | |
| Sgl_leftshiftby4(opnd2); | |
| dest_exponent += 4; | |
| } | |
| while(Sgl_iszero_hidden(opnd2)) { | |
| Sgl_leftshiftby1(opnd2); | |
| dest_exponent += 1; | |
| } | |
| } | |
| /* Divide the source mantissas */ | |
| /* | |
| * A non_restoring divide algorithm is used. | |
| */ | |
| Sgl_subtract(opnd1,opnd2,opnd1); | |
| Sgl_setzero(opnd3); | |
| for (count=1;count<=SGL_P && Sgl_all(opnd1);count++) { | |
| Sgl_leftshiftby1(opnd1); | |
| Sgl_leftshiftby1(opnd3); | |
| if (Sgl_iszero_sign(opnd1)) { | |
| Sgl_setone_lowmantissa(opnd3); | |
| Sgl_subtract(opnd1,opnd2,opnd1); | |
| } | |
| else Sgl_addition(opnd1,opnd2,opnd1); | |
| } | |
| if (count <= SGL_P) { | |
| Sgl_leftshiftby1(opnd3); | |
| Sgl_setone_lowmantissa(opnd3); | |
| Sgl_leftshift(opnd3,SGL_P-count); | |
| if (Sgl_iszero_hidden(opnd3)) { | |
| Sgl_leftshiftby1(opnd3); | |
| dest_exponent--; | |
| } | |
| } | |
| else { | |
| if (Sgl_iszero_hidden(opnd3)) { | |
| /* need to get one more bit of result */ | |
| Sgl_leftshiftby1(opnd1); | |
| Sgl_leftshiftby1(opnd3); | |
| if (Sgl_iszero_sign(opnd1)) { | |
| Sgl_setone_lowmantissa(opnd3); | |
| Sgl_subtract(opnd1,opnd2,opnd1); | |
| } | |
| else Sgl_addition(opnd1,opnd2,opnd1); | |
| dest_exponent--; | |
| } | |
| if (Sgl_iszero_sign(opnd1)) guardbit = TRUE; | |
| stickybit = Sgl_all(opnd1); | |
| } | |
| inexact = guardbit | stickybit; | |
| /* | |
| * round result | |
| */ | |
| if (inexact && (dest_exponent > 0 || Is_underflowtrap_enabled())) { | |
| Sgl_clear_signexponent(opnd3); | |
| switch (Rounding_mode()) { | |
| case ROUNDPLUS: | |
| if (Sgl_iszero_sign(result)) | |
| Sgl_increment_mantissa(opnd3); | |
| break; | |
| case ROUNDMINUS: | |
| if (Sgl_isone_sign(result)) | |
| Sgl_increment_mantissa(opnd3); | |
| break; | |
| case ROUNDNEAREST: | |
| if (guardbit) { | |
| if (stickybit || Sgl_isone_lowmantissa(opnd3)) | |
| Sgl_increment_mantissa(opnd3); | |
| } | |
| } | |
| if (Sgl_isone_hidden(opnd3)) dest_exponent++; | |
| } | |
| Sgl_set_mantissa(result,opnd3); | |
| /* | |
| * Test for overflow | |
| */ | |
| if (dest_exponent >= SGL_INFINITY_EXPONENT) { | |
| /* trap if OVERFLOWTRAP enabled */ | |
| if (Is_overflowtrap_enabled()) { | |
| /* | |
| * Adjust bias of result | |
| */ | |
| Sgl_setwrapped_exponent(result,dest_exponent,ovfl); | |
| *dstptr = result; | |
| if (inexact) | |
| if (Is_inexacttrap_enabled()) | |
| return(OVERFLOWEXCEPTION | INEXACTEXCEPTION); | |
| else Set_inexactflag(); | |
| return(OVERFLOWEXCEPTION); | |
| } | |
| Set_overflowflag(); | |
| /* set result to infinity or largest number */ | |
| Sgl_setoverflow(result); | |
| inexact = TRUE; | |
| } | |
| /* | |
| * Test for underflow | |
| */ | |
| else if (dest_exponent <= 0) { | |
| /* trap if UNDERFLOWTRAP enabled */ | |
| if (Is_underflowtrap_enabled()) { | |
| /* | |
| * Adjust bias of result | |
| */ | |
| Sgl_setwrapped_exponent(result,dest_exponent,unfl); | |
| *dstptr = result; | |
| 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 (Sgl_iszero_sign(result)) { | |
| Sgl_increment(opnd3); | |
| if (Sgl_isone_hiddenoverflow(opnd3)) | |
| is_tiny = FALSE; | |
| Sgl_decrement(opnd3); | |
| } | |
| break; | |
| case ROUNDMINUS: | |
| if (Sgl_isone_sign(result)) { | |
| Sgl_increment(opnd3); | |
| if (Sgl_isone_hiddenoverflow(opnd3)) | |
| is_tiny = FALSE; | |
| Sgl_decrement(opnd3); | |
| } | |
| break; | |
| case ROUNDNEAREST: | |
| if (guardbit && (stickybit || | |
| Sgl_isone_lowmantissa(opnd3))) { | |
| Sgl_increment(opnd3); | |
| if (Sgl_isone_hiddenoverflow(opnd3)) | |
| is_tiny = FALSE; | |
| Sgl_decrement(opnd3); | |
| } | |
| break; | |
| } | |
| } | |
| /* | |
| * denormalize result or set to signed zero | |
| */ | |
| stickybit = inexact; | |
| Sgl_denormalize(opnd3,dest_exponent,guardbit,stickybit,inexact); | |
| /* return rounded number */ | |
| if (inexact) { | |
| switch (Rounding_mode()) { | |
| case ROUNDPLUS: | |
| if (Sgl_iszero_sign(result)) { | |
| Sgl_increment(opnd3); | |
| } | |
| break; | |
| case ROUNDMINUS: | |
| if (Sgl_isone_sign(result)) { | |
| Sgl_increment(opnd3); | |
| } | |
| break; | |
| case ROUNDNEAREST: | |
| if (guardbit && (stickybit || | |
| Sgl_isone_lowmantissa(opnd3))) { | |
| Sgl_increment(opnd3); | |
| } | |
| break; | |
| } | |
| if (is_tiny) Set_underflowflag(); | |
| } | |
| Sgl_set_exponentmantissa(result,opnd3); | |
| } | |
| else Sgl_set_exponent(result,dest_exponent); | |
| *dstptr = result; | |
| /* check for inexact */ | |
| if (inexact) { | |
| if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION); | |
| else Set_inexactflag(); | |
| } | |
| return(NOEXCEPTION); | |
| } |