| // 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/dfrem.c $Revision: 1.1 $ |
| * |
| * Purpose: |
| * Double Precision Floating-point Remainder |
| * |
| * External Interfaces: |
| * dbl_frem(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 Remainder |
| */ |
| |
| int |
| dbl_frem (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 resultp1, resultp2; |
| register int opnd1_exponent, opnd2_exponent, dest_exponent, stepcount; |
| register boolean roundup = FALSE; |
| |
| Dbl_copyfromptr(srcptr1,opnd1p1,opnd1p2); |
| Dbl_copyfromptr(srcptr2,opnd2p1,opnd2p2); |
| /* |
| * check first operand for NaN's or infinity |
| */ |
| if ((opnd1_exponent = Dbl_exponent(opnd1p1)) == DBL_INFINITY_EXPONENT) { |
| if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) { |
| if (Dbl_isnotnan(opnd2p1,opnd2p2)) { |
| /* invalid since first operand is infinity */ |
| if (Is_invalidtrap_enabled()) |
| return(INVALIDEXCEPTION); |
| Set_invalidflag(); |
| Dbl_makequietnan(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 ((opnd2_exponent = Dbl_exponent(opnd2p1)) == DBL_INFINITY_EXPONENT) { |
| if (Dbl_iszero_mantissa(opnd2p1,opnd2p2)) { |
| /* |
| * return first operand |
| */ |
| Dbl_copytoptr(opnd1p1,opnd1p2,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 second operand for zero |
| */ |
| if (Dbl_iszero_exponentmantissa(opnd2p1,opnd2p2)) { |
| /* invalid since second operand is zero */ |
| if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); |
| Set_invalidflag(); |
| Dbl_makequietnan(resultp1,resultp2); |
| Dbl_copytoptr(resultp1,resultp2,dstptr); |
| return(NOEXCEPTION); |
| } |
| |
| /* |
| * get sign of result |
| */ |
| resultp1 = opnd1p1; |
| |
| /* |
| * check for denormalized operands |
| */ |
| if (opnd1_exponent == 0) { |
| /* check for zero */ |
| if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) { |
| Dbl_copytoptr(opnd1p1,opnd1p2,dstptr); |
| return(NOEXCEPTION); |
| } |
| /* normalize, then continue */ |
| opnd1_exponent = 1; |
| Dbl_normalize(opnd1p1,opnd1p2,opnd1_exponent); |
| } |
| else { |
| Dbl_clear_signexponent_set_hidden(opnd1p1); |
| } |
| if (opnd2_exponent == 0) { |
| /* normalize, then continue */ |
| opnd2_exponent = 1; |
| Dbl_normalize(opnd2p1,opnd2p2,opnd2_exponent); |
| } |
| else { |
| Dbl_clear_signexponent_set_hidden(opnd2p1); |
| } |
| |
| /* find result exponent and divide step loop count */ |
| dest_exponent = opnd2_exponent - 1; |
| stepcount = opnd1_exponent - opnd2_exponent; |
| |
| /* |
| * check for opnd1/opnd2 < 1 |
| */ |
| if (stepcount < 0) { |
| /* |
| * check for opnd1/opnd2 > 1/2 |
| * |
| * In this case n will round to 1, so |
| * r = opnd1 - opnd2 |
| */ |
| if (stepcount == -1 && |
| Dbl_isgreaterthan(opnd1p1,opnd1p2,opnd2p1,opnd2p2)) { |
| /* set sign */ |
| Dbl_allp1(resultp1) = ~Dbl_allp1(resultp1); |
| /* align opnd2 with opnd1 */ |
| Dbl_leftshiftby1(opnd2p1,opnd2p2); |
| Dbl_subtract(opnd2p1,opnd2p2,opnd1p1,opnd1p2, |
| opnd2p1,opnd2p2); |
| /* now normalize */ |
| while (Dbl_iszero_hidden(opnd2p1)) { |
| Dbl_leftshiftby1(opnd2p1,opnd2p2); |
| dest_exponent--; |
| } |
| Dbl_set_exponentmantissa(resultp1,resultp2,opnd2p1,opnd2p2); |
| goto testforunderflow; |
| } |
| /* |
| * opnd1/opnd2 <= 1/2 |
| * |
| * In this case n will round to zero, so |
| * r = opnd1 |
| */ |
| Dbl_set_exponentmantissa(resultp1,resultp2,opnd1p1,opnd1p2); |
| dest_exponent = opnd1_exponent; |
| goto testforunderflow; |
| } |
| |
| /* |
| * Generate result |
| * |
| * Do iterative subtract until remainder is less than operand 2. |
| */ |
| while (stepcount-- > 0 && (Dbl_allp1(opnd1p1) || Dbl_allp2(opnd1p2))) { |
| if (Dbl_isnotlessthan(opnd1p1,opnd1p2,opnd2p1,opnd2p2)) { |
| Dbl_subtract(opnd1p1,opnd1p2,opnd2p1,opnd2p2,opnd1p1,opnd1p2); |
| } |
| Dbl_leftshiftby1(opnd1p1,opnd1p2); |
| } |
| /* |
| * Do last subtract, then determine which way to round if remainder |
| * is exactly 1/2 of opnd2 |
| */ |
| if (Dbl_isnotlessthan(opnd1p1,opnd1p2,opnd2p1,opnd2p2)) { |
| Dbl_subtract(opnd1p1,opnd1p2,opnd2p1,opnd2p2,opnd1p1,opnd1p2); |
| roundup = TRUE; |
| } |
| if (stepcount > 0 || Dbl_iszero(opnd1p1,opnd1p2)) { |
| /* division is exact, remainder is zero */ |
| Dbl_setzero_exponentmantissa(resultp1,resultp2); |
| Dbl_copytoptr(resultp1,resultp2,dstptr); |
| return(NOEXCEPTION); |
| } |
| |
| /* |
| * Check for cases where opnd1/opnd2 < n |
| * |
| * In this case the result's sign will be opposite that of |
| * opnd1. The mantissa also needs some correction. |
| */ |
| Dbl_leftshiftby1(opnd1p1,opnd1p2); |
| if (Dbl_isgreaterthan(opnd1p1,opnd1p2,opnd2p1,opnd2p2)) { |
| Dbl_invert_sign(resultp1); |
| Dbl_leftshiftby1(opnd2p1,opnd2p2); |
| Dbl_subtract(opnd2p1,opnd2p2,opnd1p1,opnd1p2,opnd1p1,opnd1p2); |
| } |
| /* check for remainder being exactly 1/2 of opnd2 */ |
| else if (Dbl_isequal(opnd1p1,opnd1p2,opnd2p1,opnd2p2) && roundup) { |
| Dbl_invert_sign(resultp1); |
| } |
| |
| /* normalize result's mantissa */ |
| while (Dbl_iszero_hidden(opnd1p1)) { |
| dest_exponent--; |
| Dbl_leftshiftby1(opnd1p1,opnd1p2); |
| } |
| Dbl_set_exponentmantissa(resultp1,resultp2,opnd1p1,opnd1p2); |
| |
| /* |
| * Test for underflow |
| */ |
| testforunderflow: |
| if (dest_exponent <= 0) { |
| /* trap if UNDERFLOWTRAP enabled */ |
| if (Is_underflowtrap_enabled()) { |
| /* |
| * Adjust bias of result |
| */ |
| Dbl_setwrapped_exponent(resultp1,dest_exponent,unfl); |
| /* frem is always exact */ |
| Dbl_copytoptr(resultp1,resultp2,dstptr); |
| return(UNDERFLOWEXCEPTION); |
| } |
| /* |
| * denormalize result or set to signed zero |
| */ |
| if (dest_exponent >= (1 - DBL_P)) { |
| Dbl_rightshift_exponentmantissa(resultp1,resultp2, |
| 1-dest_exponent); |
| } |
| else { |
| Dbl_setzero_exponentmantissa(resultp1,resultp2); |
| } |
| } |
| else Dbl_set_exponent(resultp1,dest_exponent); |
| Dbl_copytoptr(resultp1,resultp2,dstptr); |
| return(NOEXCEPTION); |
| } |
