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284 lines
8.1 KiB
284 lines
8.1 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Linux/PA-RISC Project (http://www.parisc-linux.org/) |
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* |
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* Floating-point emulation code |
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* Copyright (C) 2001 Hewlett-Packard (Paul Bame) <[email protected]> |
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*/ |
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/* |
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* BEGIN_DESC |
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* |
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* File: |
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* @(#) pa/spmath/dfrem.c $Revision: 1.1 $ |
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* |
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* Purpose: |
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* Double Precision Floating-point Remainder |
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* |
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* External Interfaces: |
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* dbl_frem(srcptr1,srcptr2,dstptr,status) |
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* |
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* Internal Interfaces: |
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* |
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* Theory: |
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* <<please update with a overview of the operation of this file>> |
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* |
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* END_DESC |
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*/ |
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#include "float.h" |
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#include "dbl_float.h" |
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/* |
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* Double Precision Floating-point Remainder |
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*/ |
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int |
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dbl_frem (dbl_floating_point * srcptr1, dbl_floating_point * srcptr2, |
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dbl_floating_point * dstptr, unsigned int *status) |
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{ |
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register unsigned int opnd1p1, opnd1p2, opnd2p1, opnd2p2; |
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register unsigned int resultp1, resultp2; |
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register int opnd1_exponent, opnd2_exponent, dest_exponent, stepcount; |
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register boolean roundup = FALSE; |
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Dbl_copyfromptr(srcptr1,opnd1p1,opnd1p2); |
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Dbl_copyfromptr(srcptr2,opnd2p1,opnd2p2); |
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/* |
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* check first operand for NaN's or infinity |
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*/ |
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if ((opnd1_exponent = Dbl_exponent(opnd1p1)) == DBL_INFINITY_EXPONENT) { |
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if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) { |
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if (Dbl_isnotnan(opnd2p1,opnd2p2)) { |
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/* invalid since first operand is infinity */ |
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if (Is_invalidtrap_enabled()) |
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return(INVALIDEXCEPTION); |
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Set_invalidflag(); |
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Dbl_makequietnan(resultp1,resultp2); |
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Dbl_copytoptr(resultp1,resultp2,dstptr); |
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return(NOEXCEPTION); |
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} |
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} |
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else { |
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/* |
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* is NaN; signaling or quiet? |
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*/ |
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if (Dbl_isone_signaling(opnd1p1)) { |
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/* trap if INVALIDTRAP enabled */ |
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if (Is_invalidtrap_enabled()) |
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return(INVALIDEXCEPTION); |
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/* make NaN quiet */ |
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Set_invalidflag(); |
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Dbl_set_quiet(opnd1p1); |
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} |
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/* |
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* is second operand a signaling NaN? |
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*/ |
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else if (Dbl_is_signalingnan(opnd2p1)) { |
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/* trap if INVALIDTRAP enabled */ |
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if (Is_invalidtrap_enabled()) |
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return(INVALIDEXCEPTION); |
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/* make NaN quiet */ |
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Set_invalidflag(); |
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Dbl_set_quiet(opnd2p1); |
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Dbl_copytoptr(opnd2p1,opnd2p2,dstptr); |
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return(NOEXCEPTION); |
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} |
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/* |
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* return quiet NaN |
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*/ |
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Dbl_copytoptr(opnd1p1,opnd1p2,dstptr); |
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return(NOEXCEPTION); |
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} |
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} |
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/* |
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* check second operand for NaN's or infinity |
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*/ |
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if ((opnd2_exponent = Dbl_exponent(opnd2p1)) == DBL_INFINITY_EXPONENT) { |
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if (Dbl_iszero_mantissa(opnd2p1,opnd2p2)) { |
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/* |
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* return first operand |
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*/ |
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Dbl_copytoptr(opnd1p1,opnd1p2,dstptr); |
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return(NOEXCEPTION); |
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} |
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/* |
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* is NaN; signaling or quiet? |
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*/ |
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if (Dbl_isone_signaling(opnd2p1)) { |
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/* trap if INVALIDTRAP enabled */ |
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if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); |
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/* make NaN quiet */ |
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Set_invalidflag(); |
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Dbl_set_quiet(opnd2p1); |
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} |
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/* |
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* return quiet NaN |
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*/ |
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Dbl_copytoptr(opnd2p1,opnd2p2,dstptr); |
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return(NOEXCEPTION); |
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} |
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/* |
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* check second operand for zero |
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*/ |
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if (Dbl_iszero_exponentmantissa(opnd2p1,opnd2p2)) { |
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/* invalid since second operand is zero */ |
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if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); |
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Set_invalidflag(); |
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Dbl_makequietnan(resultp1,resultp2); |
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Dbl_copytoptr(resultp1,resultp2,dstptr); |
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return(NOEXCEPTION); |
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} |
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/* |
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* get sign of result |
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*/ |
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resultp1 = opnd1p1; |
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/* |
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* check for denormalized operands |
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*/ |
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if (opnd1_exponent == 0) { |
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/* check for zero */ |
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if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) { |
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Dbl_copytoptr(opnd1p1,opnd1p2,dstptr); |
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return(NOEXCEPTION); |
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} |
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/* normalize, then continue */ |
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opnd1_exponent = 1; |
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Dbl_normalize(opnd1p1,opnd1p2,opnd1_exponent); |
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} |
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else { |
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Dbl_clear_signexponent_set_hidden(opnd1p1); |
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} |
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if (opnd2_exponent == 0) { |
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/* normalize, then continue */ |
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opnd2_exponent = 1; |
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Dbl_normalize(opnd2p1,opnd2p2,opnd2_exponent); |
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} |
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else { |
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Dbl_clear_signexponent_set_hidden(opnd2p1); |
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} |
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/* find result exponent and divide step loop count */ |
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dest_exponent = opnd2_exponent - 1; |
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stepcount = opnd1_exponent - opnd2_exponent; |
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/* |
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* check for opnd1/opnd2 < 1 |
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*/ |
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if (stepcount < 0) { |
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/* |
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* check for opnd1/opnd2 > 1/2 |
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* |
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* In this case n will round to 1, so |
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* r = opnd1 - opnd2 |
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*/ |
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if (stepcount == -1 && |
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Dbl_isgreaterthan(opnd1p1,opnd1p2,opnd2p1,opnd2p2)) { |
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/* set sign */ |
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Dbl_allp1(resultp1) = ~Dbl_allp1(resultp1); |
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/* align opnd2 with opnd1 */ |
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Dbl_leftshiftby1(opnd2p1,opnd2p2); |
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Dbl_subtract(opnd2p1,opnd2p2,opnd1p1,opnd1p2, |
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opnd2p1,opnd2p2); |
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/* now normalize */ |
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while (Dbl_iszero_hidden(opnd2p1)) { |
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Dbl_leftshiftby1(opnd2p1,opnd2p2); |
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dest_exponent--; |
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} |
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Dbl_set_exponentmantissa(resultp1,resultp2,opnd2p1,opnd2p2); |
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goto testforunderflow; |
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} |
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/* |
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* opnd1/opnd2 <= 1/2 |
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* |
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* In this case n will round to zero, so |
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* r = opnd1 |
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*/ |
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Dbl_set_exponentmantissa(resultp1,resultp2,opnd1p1,opnd1p2); |
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dest_exponent = opnd1_exponent; |
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goto testforunderflow; |
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} |
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/* |
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* Generate result |
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* |
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* Do iterative subtract until remainder is less than operand 2. |
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*/ |
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while (stepcount-- > 0 && (Dbl_allp1(opnd1p1) || Dbl_allp2(opnd1p2))) { |
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if (Dbl_isnotlessthan(opnd1p1,opnd1p2,opnd2p1,opnd2p2)) { |
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Dbl_subtract(opnd1p1,opnd1p2,opnd2p1,opnd2p2,opnd1p1,opnd1p2); |
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} |
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Dbl_leftshiftby1(opnd1p1,opnd1p2); |
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} |
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/* |
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* Do last subtract, then determine which way to round if remainder |
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* is exactly 1/2 of opnd2 |
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*/ |
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if (Dbl_isnotlessthan(opnd1p1,opnd1p2,opnd2p1,opnd2p2)) { |
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Dbl_subtract(opnd1p1,opnd1p2,opnd2p1,opnd2p2,opnd1p1,opnd1p2); |
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roundup = TRUE; |
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} |
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if (stepcount > 0 || Dbl_iszero(opnd1p1,opnd1p2)) { |
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/* division is exact, remainder is zero */ |
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Dbl_setzero_exponentmantissa(resultp1,resultp2); |
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Dbl_copytoptr(resultp1,resultp2,dstptr); |
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return(NOEXCEPTION); |
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} |
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/* |
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* Check for cases where opnd1/opnd2 < n |
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* |
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* In this case the result's sign will be opposite that of |
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* opnd1. The mantissa also needs some correction. |
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*/ |
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Dbl_leftshiftby1(opnd1p1,opnd1p2); |
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if (Dbl_isgreaterthan(opnd1p1,opnd1p2,opnd2p1,opnd2p2)) { |
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Dbl_invert_sign(resultp1); |
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Dbl_leftshiftby1(opnd2p1,opnd2p2); |
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Dbl_subtract(opnd2p1,opnd2p2,opnd1p1,opnd1p2,opnd1p1,opnd1p2); |
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} |
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/* check for remainder being exactly 1/2 of opnd2 */ |
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else if (Dbl_isequal(opnd1p1,opnd1p2,opnd2p1,opnd2p2) && roundup) { |
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Dbl_invert_sign(resultp1); |
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} |
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/* normalize result's mantissa */ |
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while (Dbl_iszero_hidden(opnd1p1)) { |
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dest_exponent--; |
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Dbl_leftshiftby1(opnd1p1,opnd1p2); |
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} |
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Dbl_set_exponentmantissa(resultp1,resultp2,opnd1p1,opnd1p2); |
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/* |
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* Test for underflow |
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*/ |
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testforunderflow: |
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if (dest_exponent <= 0) { |
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/* trap if UNDERFLOWTRAP enabled */ |
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if (Is_underflowtrap_enabled()) { |
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/* |
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* Adjust bias of result |
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*/ |
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Dbl_setwrapped_exponent(resultp1,dest_exponent,unfl); |
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/* frem is always exact */ |
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Dbl_copytoptr(resultp1,resultp2,dstptr); |
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return(UNDERFLOWEXCEPTION); |
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} |
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/* |
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* denormalize result or set to signed zero |
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*/ |
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if (dest_exponent >= (1 - DBL_P)) { |
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Dbl_rightshift_exponentmantissa(resultp1,resultp2, |
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1-dest_exponent); |
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} |
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else { |
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Dbl_setzero_exponentmantissa(resultp1,resultp2); |
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} |
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} |
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else Dbl_set_exponent(resultp1,dest_exponent); |
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Dbl_copytoptr(resultp1,resultp2,dstptr); |
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return(NOEXCEPTION); |
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}
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