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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /arch/parisc/math-emu/dfdiv.c
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+/*
+ * 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 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);
+}