patch-2.4.20 linux-2.4.20/arch/parisc/math-emu/dfdiv.c

• Lines: 401
• Date: Thu Nov 28 15:53:10 2002
• Orig file: linux-2.4.19/arch/parisc/math-emu/dfdiv.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -urN linux-2.4.19/arch/parisc/math-emu/dfdiv.c linux-2.4.20/arch/parisc/math-emu/dfdiv.c
@@ -0,0 +1,400 @@
+/*
+ * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+/*
+ * 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);
+}