| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* |
| * Linux/PA-RISC Project (http://www.parisc-linux.org/) |
| * |
| * Floating-point emulation code |
| * Copyright (C) 2001 Hewlett-Packard (Paul Bame) <bame@debian.org> |
| */ |
| /* |
| * BEGIN_DESC |
| * |
| * File: |
| * @(#) pa/spmath/dfdiv.c $Revision: 1.1 $ |
| * |
| * Purpose: |
| * Double Precision Floating-point Divide |
| * |
| * External Interfaces: |
| * dbl_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 "dbl_float.h" |
| |
| /* |
| * Double Precision Floating-point Divide |
| */ |
| |
| int |
| dbl_fdiv (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_isinfinity(opnd2p1,opnd2p2)) { |
| /* |
| * invalid since both operands |
| * are infinity |
| */ |
| 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)) { |
| /* |
| * return zero |
| */ |
| Dbl_setzero_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); |
| } |
| /* |
| * check for division by zero |
| */ |
| if (Dbl_iszero_exponentmantissa(opnd2p1,opnd2p2)) { |
| if (Dbl_iszero_exponentmantissa(opnd1p1,opnd1p2)) { |
| /* invalid since both operands are zero */ |
| if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); |
| Set_invalidflag(); |
| Dbl_makequietnan(resultp1,resultp2); |
| Dbl_copytoptr(resultp1,resultp2,dstptr); |
| return(NOEXCEPTION); |
| } |
| if (Is_divisionbyzerotrap_enabled()) |
| return(DIVISIONBYZEROEXCEPTION); |
| Set_divisionbyzeroflag(); |
| Dbl_setinfinity_exponentmantissa(resultp1,resultp2); |
| Dbl_copytoptr(resultp1,resultp2,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, want to normalize */ |
| 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 { |
| /* is denormalized; want to normalize */ |
| Dbl_clear_signexponent(opnd2p1); |
| Dbl_leftshiftby1(opnd2p1,opnd2p2); |
| while (Dbl_iszero_hiddenhigh7mantissa(opnd2p1)) { |
| dest_exponent+=8; |
| Dbl_leftshiftby8(opnd2p1,opnd2p2); |
| } |
| if (Dbl_iszero_hiddenhigh3mantissa(opnd2p1)) { |
| dest_exponent+=4; |
| Dbl_leftshiftby4(opnd2p1,opnd2p2); |
| } |
| while (Dbl_iszero_hidden(opnd2p1)) { |
| dest_exponent++; |
| Dbl_leftshiftby1(opnd2p1,opnd2p2); |
| } |
| } |
| |
| /* Divide the source mantissas */ |
| |
| /* |
| * A non-restoring divide algorithm is used. |
| */ |
| Twoword_subtract(opnd1p1,opnd1p2,opnd2p1,opnd2p2); |
| Dbl_setzero(opnd3p1,opnd3p2); |
| for (count=1; count <= DBL_P && (opnd1p1 || opnd1p2); count++) { |
| Dbl_leftshiftby1(opnd1p1,opnd1p2); |
| Dbl_leftshiftby1(opnd3p1,opnd3p2); |
| if (Dbl_iszero_sign(opnd1p1)) { |
| Dbl_setone_lowmantissap2(opnd3p2); |
| Twoword_subtract(opnd1p1,opnd1p2,opnd2p1,opnd2p2); |
| } |
| else { |
| Twoword_add(opnd1p1, opnd1p2, opnd2p1, opnd2p2); |
| } |
| } |
| if (count <= DBL_P) { |
| Dbl_leftshiftby1(opnd3p1,opnd3p2); |
| Dbl_setone_lowmantissap2(opnd3p2); |
| Dbl_leftshift(opnd3p1,opnd3p2,(DBL_P-count)); |
| if (Dbl_iszero_hidden(opnd3p1)) { |
| Dbl_leftshiftby1(opnd3p1,opnd3p2); |
| dest_exponent--; |
| } |
| } |
| else { |
| if (Dbl_iszero_hidden(opnd3p1)) { |
| /* need to get one more bit of result */ |
| Dbl_leftshiftby1(opnd1p1,opnd1p2); |
| Dbl_leftshiftby1(opnd3p1,opnd3p2); |
| if (Dbl_iszero_sign(opnd1p1)) { |
| Dbl_setone_lowmantissap2(opnd3p2); |
| Twoword_subtract(opnd1p1,opnd1p2,opnd2p1,opnd2p2); |
| } |
| else { |
| Twoword_add(opnd1p1,opnd1p2,opnd2p1,opnd2p2); |
| } |
| dest_exponent--; |
| } |
| if (Dbl_iszero_sign(opnd1p1)) guardbit = TRUE; |
| stickybit = Dbl_allp1(opnd1p1) || Dbl_allp2(opnd1p2); |
| } |
| inexact = guardbit | stickybit; |
| |
| /* |
| * 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 && (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); |
| } |
| Set_overflowflag(); |
| /* set result to infinity or largest number */ |
| Dbl_setoverflow(resultp1,resultp2); |
| inexact = TRUE; |
| } |
| /* |
| * 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 rounded 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); |
| Dbl_copytoptr(resultp1,resultp2,dstptr); |
| |
| /* check for inexact */ |
| if (inexact) { |
| if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION); |
| else Set_inexactflag(); |
| } |
| return(NOEXCEPTION); |
| } |
