/* $OpenBSD: sfrem.c,v 1.3 1998/07/02 19:05:59 mickey Exp $ */ /* * Copyright 1996 1995 by Open Software Foundation, Inc. * All Rights Reserved * * Permission to use, copy, modify, and distribute this software and * its documentation for any purpose and without fee is hereby granted, * provided that the above copyright notice appears in all copies and * that both the copyright notice and this permission notice appear in * supporting documentation. * * OSF DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS * FOR A PARTICULAR PURPOSE. * * IN NO EVENT SHALL OSF BE LIABLE FOR ANY SPECIAL, INDIRECT, OR * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM * LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT, * NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. * */ /* * pmk1.1 */ /* * (c) Copyright 1986 HEWLETT-PACKARD COMPANY * * To anyone who acknowledges that this file is provided "AS IS" * without any express or implied warranty: * permission to use, copy, modify, and distribute this file * for any purpose is hereby granted without fee, provided that * the above copyright notice and this notice appears in all * copies, and that the name of Hewlett-Packard Company not be * used in advertising or publicity pertaining to distribution * of the software without specific, written prior permission. * Hewlett-Packard Company makes no representations about the * suitability of this software for any purpose. */ #include "../spmath/float.h" #include "../spmath/sgl_float.h" /* * Single Precision Floating-point Remainder */ int sgl_frem(srcptr1,srcptr2,dstptr,status) sgl_floating_point *srcptr1, *srcptr2, *dstptr; unsigned int *status; { register unsigned int opnd1, opnd2, result; register int opnd1_exponent, opnd2_exponent, dest_exponent, stepcount; register boolean roundup = FALSE; opnd1 = *srcptr1; opnd2 = *srcptr2; /* * check first operand for NaN's or infinity */ if ((opnd1_exponent = Sgl_exponent(opnd1)) == SGL_INFINITY_EXPONENT) { if (Sgl_iszero_mantissa(opnd1)) { if (Sgl_isnotnan(opnd2)) { /* invalid since first operand is infinity */ if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); Set_invalidflag(); Sgl_makequietnan(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 ((opnd2_exponent = Sgl_exponent(opnd2)) == SGL_INFINITY_EXPONENT) { if (Sgl_iszero_mantissa(opnd2)) { /* * return first operand */ *dstptr = opnd1; 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 second operand for zero */ if (Sgl_iszero_exponentmantissa(opnd2)) { /* invalid since second operand is zero */ if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); Set_invalidflag(); Sgl_makequietnan(result); *dstptr = result; return(NOEXCEPTION); } /* * get sign of result */ result = opnd1; /* * check for denormalized operands */ if (opnd1_exponent == 0) { /* check for zero */ if (Sgl_iszero_mantissa(opnd1)) { *dstptr = opnd1; return(NOEXCEPTION); } /* normalize, then continue */ opnd1_exponent = 1; Sgl_normalize(opnd1,opnd1_exponent); } else { Sgl_clear_signexponent_set_hidden(opnd1); } if (opnd2_exponent == 0) { /* normalize, then continue */ opnd2_exponent = 1; Sgl_normalize(opnd2,opnd2_exponent); } else { Sgl_clear_signexponent_set_hidden(opnd2); } /* 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 && Sgl_isgreaterthan(opnd1,opnd2)) { Sgl_all(result) = ~Sgl_all(result); /* set sign */ /* align opnd2 with opnd1 */ Sgl_leftshiftby1(opnd2); Sgl_subtract(opnd2,opnd1,opnd2); /* now normalize */ while (Sgl_iszero_hidden(opnd2)) { Sgl_leftshiftby1(opnd2); dest_exponent--; } Sgl_set_exponentmantissa(result,opnd2); goto testforunderflow; } /* * opnd1/opnd2 <= 1/2 * * In this case n will round to zero, so * r = opnd1 */ Sgl_set_exponentmantissa(result,opnd1); dest_exponent = opnd1_exponent; goto testforunderflow; } /* * Generate result * * Do iterative subtract until remainder is less than operand 2. */ while (stepcount-- > 0 && Sgl_all(opnd1)) { if (Sgl_isnotlessthan(opnd1,opnd2)) Sgl_subtract(opnd1,opnd2,opnd1); Sgl_leftshiftby1(opnd1); } /* * Do last subtract, then determine which way to round if remainder * is exactly 1/2 of opnd2 */ if (Sgl_isnotlessthan(opnd1,opnd2)) { Sgl_subtract(opnd1,opnd2,opnd1); roundup = TRUE; } if (stepcount > 0 || Sgl_iszero(opnd1)) { /* division is exact, remainder is zero */ Sgl_setzero_exponentmantissa(result); *dstptr = result; 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. */ Sgl_leftshiftby1(opnd1); if (Sgl_isgreaterthan(opnd1,opnd2)) { Sgl_invert_sign(result); Sgl_subtract((opnd2<<1),opnd1,opnd1); } /* check for remainder being exactly 1/2 of opnd2 */ else if (Sgl_isequal(opnd1,opnd2) && roundup) { Sgl_invert_sign(result); } /* normalize result's mantissa */ while (Sgl_iszero_hidden(opnd1)) { dest_exponent--; Sgl_leftshiftby1(opnd1); } Sgl_set_exponentmantissa(result,opnd1); /* * Test for underflow */ testforunderflow: 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; /* frem is always exact */ return(UNDERFLOWEXCEPTION); } /* * denormalize result or set to signed zero */ if (dest_exponent >= (1 - SGL_P)) { Sgl_rightshift_exponentmantissa(result,1-dest_exponent); } else { Sgl_setzero_exponentmantissa(result); } } else Sgl_set_exponent(result,dest_exponent); *dstptr = result; return(NOEXCEPTION); }