1*660662f8SThomas Gleixner // SPDX-License-Identifier: GPL-2.0-or-later
21da177e4SLinus Torvalds /*
31da177e4SLinus Torvalds * Linux/PA-RISC Project (http://www.parisc-linux.org/)
41da177e4SLinus Torvalds *
51da177e4SLinus Torvalds * Floating-point emulation code
61da177e4SLinus Torvalds * Copyright (C) 2001 Hewlett-Packard (Paul Bame) <bame@debian.org>
71da177e4SLinus Torvalds */
81da177e4SLinus Torvalds /*
91da177e4SLinus Torvalds * BEGIN_DESC
101da177e4SLinus Torvalds *
111da177e4SLinus Torvalds * File:
121da177e4SLinus Torvalds * @(#) pa/spmath/sfdiv.c $Revision: 1.1 $
131da177e4SLinus Torvalds *
141da177e4SLinus Torvalds * Purpose:
151da177e4SLinus Torvalds * Single Precision Floating-point Divide
161da177e4SLinus Torvalds *
171da177e4SLinus Torvalds * External Interfaces:
181da177e4SLinus Torvalds * sgl_fdiv(srcptr1,srcptr2,dstptr,status)
191da177e4SLinus Torvalds *
201da177e4SLinus Torvalds * Internal Interfaces:
211da177e4SLinus Torvalds *
221da177e4SLinus Torvalds * Theory:
231da177e4SLinus Torvalds * <<please update with a overview of the operation of this file>>
241da177e4SLinus Torvalds *
251da177e4SLinus Torvalds * END_DESC
261da177e4SLinus Torvalds */
271da177e4SLinus Torvalds
281da177e4SLinus Torvalds
291da177e4SLinus Torvalds #include "float.h"
301da177e4SLinus Torvalds #include "sgl_float.h"
311da177e4SLinus Torvalds
321da177e4SLinus Torvalds /*
331da177e4SLinus Torvalds * Single Precision Floating-point Divide
341da177e4SLinus Torvalds */
351da177e4SLinus Torvalds
361da177e4SLinus Torvalds int
sgl_fdiv(sgl_floating_point * srcptr1,sgl_floating_point * srcptr2,sgl_floating_point * dstptr,unsigned int * status)371da177e4SLinus Torvalds sgl_fdiv (sgl_floating_point * srcptr1, sgl_floating_point * srcptr2,
381da177e4SLinus Torvalds sgl_floating_point * dstptr, unsigned int *status)
391da177e4SLinus Torvalds {
401da177e4SLinus Torvalds register unsigned int opnd1, opnd2, opnd3, result;
411da177e4SLinus Torvalds register int dest_exponent, count;
421da177e4SLinus Torvalds register boolean inexact = FALSE, guardbit = FALSE, stickybit = FALSE;
431da177e4SLinus Torvalds boolean is_tiny;
441da177e4SLinus Torvalds
451da177e4SLinus Torvalds opnd1 = *srcptr1;
461da177e4SLinus Torvalds opnd2 = *srcptr2;
471da177e4SLinus Torvalds /*
481da177e4SLinus Torvalds * set sign bit of result
491da177e4SLinus Torvalds */
501da177e4SLinus Torvalds if (Sgl_sign(opnd1) ^ Sgl_sign(opnd2)) Sgl_setnegativezero(result);
511da177e4SLinus Torvalds else Sgl_setzero(result);
521da177e4SLinus Torvalds /*
531da177e4SLinus Torvalds * check first operand for NaN's or infinity
541da177e4SLinus Torvalds */
551da177e4SLinus Torvalds if (Sgl_isinfinity_exponent(opnd1)) {
561da177e4SLinus Torvalds if (Sgl_iszero_mantissa(opnd1)) {
571da177e4SLinus Torvalds if (Sgl_isnotnan(opnd2)) {
581da177e4SLinus Torvalds if (Sgl_isinfinity(opnd2)) {
591da177e4SLinus Torvalds /*
601da177e4SLinus Torvalds * invalid since both operands
611da177e4SLinus Torvalds * are infinity
621da177e4SLinus Torvalds */
631da177e4SLinus Torvalds if (Is_invalidtrap_enabled())
641da177e4SLinus Torvalds return(INVALIDEXCEPTION);
651da177e4SLinus Torvalds Set_invalidflag();
661da177e4SLinus Torvalds Sgl_makequietnan(result);
671da177e4SLinus Torvalds *dstptr = result;
681da177e4SLinus Torvalds return(NOEXCEPTION);
691da177e4SLinus Torvalds }
701da177e4SLinus Torvalds /*
711da177e4SLinus Torvalds * return infinity
721da177e4SLinus Torvalds */
731da177e4SLinus Torvalds Sgl_setinfinity_exponentmantissa(result);
741da177e4SLinus Torvalds *dstptr = result;
751da177e4SLinus Torvalds return(NOEXCEPTION);
761da177e4SLinus Torvalds }
771da177e4SLinus Torvalds }
781da177e4SLinus Torvalds else {
791da177e4SLinus Torvalds /*
801da177e4SLinus Torvalds * is NaN; signaling or quiet?
811da177e4SLinus Torvalds */
821da177e4SLinus Torvalds if (Sgl_isone_signaling(opnd1)) {
831da177e4SLinus Torvalds /* trap if INVALIDTRAP enabled */
841da177e4SLinus Torvalds if (Is_invalidtrap_enabled())
851da177e4SLinus Torvalds return(INVALIDEXCEPTION);
861da177e4SLinus Torvalds /* make NaN quiet */
871da177e4SLinus Torvalds Set_invalidflag();
881da177e4SLinus Torvalds Sgl_set_quiet(opnd1);
891da177e4SLinus Torvalds }
901da177e4SLinus Torvalds /*
911da177e4SLinus Torvalds * is second operand a signaling NaN?
921da177e4SLinus Torvalds */
931da177e4SLinus Torvalds else if (Sgl_is_signalingnan(opnd2)) {
941da177e4SLinus Torvalds /* trap if INVALIDTRAP enabled */
951da177e4SLinus Torvalds if (Is_invalidtrap_enabled())
961da177e4SLinus Torvalds return(INVALIDEXCEPTION);
971da177e4SLinus Torvalds /* make NaN quiet */
981da177e4SLinus Torvalds Set_invalidflag();
991da177e4SLinus Torvalds Sgl_set_quiet(opnd2);
1001da177e4SLinus Torvalds *dstptr = opnd2;
1011da177e4SLinus Torvalds return(NOEXCEPTION);
1021da177e4SLinus Torvalds }
1031da177e4SLinus Torvalds /*
1041da177e4SLinus Torvalds * return quiet NaN
1051da177e4SLinus Torvalds */
1061da177e4SLinus Torvalds *dstptr = opnd1;
1071da177e4SLinus Torvalds return(NOEXCEPTION);
1081da177e4SLinus Torvalds }
1091da177e4SLinus Torvalds }
1101da177e4SLinus Torvalds /*
1111da177e4SLinus Torvalds * check second operand for NaN's or infinity
1121da177e4SLinus Torvalds */
1131da177e4SLinus Torvalds if (Sgl_isinfinity_exponent(opnd2)) {
1141da177e4SLinus Torvalds if (Sgl_iszero_mantissa(opnd2)) {
1151da177e4SLinus Torvalds /*
1161da177e4SLinus Torvalds * return zero
1171da177e4SLinus Torvalds */
1181da177e4SLinus Torvalds Sgl_setzero_exponentmantissa(result);
1191da177e4SLinus Torvalds *dstptr = result;
1201da177e4SLinus Torvalds return(NOEXCEPTION);
1211da177e4SLinus Torvalds }
1221da177e4SLinus Torvalds /*
1231da177e4SLinus Torvalds * is NaN; signaling or quiet?
1241da177e4SLinus Torvalds */
1251da177e4SLinus Torvalds if (Sgl_isone_signaling(opnd2)) {
1261da177e4SLinus Torvalds /* trap if INVALIDTRAP enabled */
1271da177e4SLinus Torvalds if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
1281da177e4SLinus Torvalds /* make NaN quiet */
1291da177e4SLinus Torvalds Set_invalidflag();
1301da177e4SLinus Torvalds Sgl_set_quiet(opnd2);
1311da177e4SLinus Torvalds }
1321da177e4SLinus Torvalds /*
1331da177e4SLinus Torvalds * return quiet NaN
1341da177e4SLinus Torvalds */
1351da177e4SLinus Torvalds *dstptr = opnd2;
1361da177e4SLinus Torvalds return(NOEXCEPTION);
1371da177e4SLinus Torvalds }
1381da177e4SLinus Torvalds /*
1391da177e4SLinus Torvalds * check for division by zero
1401da177e4SLinus Torvalds */
1411da177e4SLinus Torvalds if (Sgl_iszero_exponentmantissa(opnd2)) {
1421da177e4SLinus Torvalds if (Sgl_iszero_exponentmantissa(opnd1)) {
1431da177e4SLinus Torvalds /* invalid since both operands are zero */
1441da177e4SLinus Torvalds if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
1451da177e4SLinus Torvalds Set_invalidflag();
1461da177e4SLinus Torvalds Sgl_makequietnan(result);
1471da177e4SLinus Torvalds *dstptr = result;
1481da177e4SLinus Torvalds return(NOEXCEPTION);
1491da177e4SLinus Torvalds }
1501da177e4SLinus Torvalds if (Is_divisionbyzerotrap_enabled())
1511da177e4SLinus Torvalds return(DIVISIONBYZEROEXCEPTION);
1521da177e4SLinus Torvalds Set_divisionbyzeroflag();
1531da177e4SLinus Torvalds Sgl_setinfinity_exponentmantissa(result);
1541da177e4SLinus Torvalds *dstptr = result;
1551da177e4SLinus Torvalds return(NOEXCEPTION);
1561da177e4SLinus Torvalds }
1571da177e4SLinus Torvalds /*
1581da177e4SLinus Torvalds * Generate exponent
1591da177e4SLinus Torvalds */
1601da177e4SLinus Torvalds dest_exponent = Sgl_exponent(opnd1) - Sgl_exponent(opnd2) + SGL_BIAS;
1611da177e4SLinus Torvalds
1621da177e4SLinus Torvalds /*
1631da177e4SLinus Torvalds * Generate mantissa
1641da177e4SLinus Torvalds */
1651da177e4SLinus Torvalds if (Sgl_isnotzero_exponent(opnd1)) {
1661da177e4SLinus Torvalds /* set hidden bit */
1671da177e4SLinus Torvalds Sgl_clear_signexponent_set_hidden(opnd1);
1681da177e4SLinus Torvalds }
1691da177e4SLinus Torvalds else {
1701da177e4SLinus Torvalds /* check for zero */
1711da177e4SLinus Torvalds if (Sgl_iszero_mantissa(opnd1)) {
1721da177e4SLinus Torvalds Sgl_setzero_exponentmantissa(result);
1731da177e4SLinus Torvalds *dstptr = result;
1741da177e4SLinus Torvalds return(NOEXCEPTION);
1751da177e4SLinus Torvalds }
1761da177e4SLinus Torvalds /* is denormalized; want to normalize */
1771da177e4SLinus Torvalds Sgl_clear_signexponent(opnd1);
1781da177e4SLinus Torvalds Sgl_leftshiftby1(opnd1);
1791da177e4SLinus Torvalds Sgl_normalize(opnd1,dest_exponent);
1801da177e4SLinus Torvalds }
1811da177e4SLinus Torvalds /* opnd2 needs to have hidden bit set with msb in hidden bit */
1821da177e4SLinus Torvalds if (Sgl_isnotzero_exponent(opnd2)) {
1831da177e4SLinus Torvalds Sgl_clear_signexponent_set_hidden(opnd2);
1841da177e4SLinus Torvalds }
1851da177e4SLinus Torvalds else {
1861da177e4SLinus Torvalds /* is denormalized; want to normalize */
1871da177e4SLinus Torvalds Sgl_clear_signexponent(opnd2);
1881da177e4SLinus Torvalds Sgl_leftshiftby1(opnd2);
1891da177e4SLinus Torvalds while(Sgl_iszero_hiddenhigh7mantissa(opnd2)) {
1901da177e4SLinus Torvalds Sgl_leftshiftby8(opnd2);
1911da177e4SLinus Torvalds dest_exponent += 8;
1921da177e4SLinus Torvalds }
1931da177e4SLinus Torvalds if(Sgl_iszero_hiddenhigh3mantissa(opnd2)) {
1941da177e4SLinus Torvalds Sgl_leftshiftby4(opnd2);
1951da177e4SLinus Torvalds dest_exponent += 4;
1961da177e4SLinus Torvalds }
1971da177e4SLinus Torvalds while(Sgl_iszero_hidden(opnd2)) {
1981da177e4SLinus Torvalds Sgl_leftshiftby1(opnd2);
1991da177e4SLinus Torvalds dest_exponent += 1;
2001da177e4SLinus Torvalds }
2011da177e4SLinus Torvalds }
2021da177e4SLinus Torvalds
2031da177e4SLinus Torvalds /* Divide the source mantissas */
2041da177e4SLinus Torvalds
2051da177e4SLinus Torvalds /*
2061da177e4SLinus Torvalds * A non_restoring divide algorithm is used.
2071da177e4SLinus Torvalds */
2081da177e4SLinus Torvalds Sgl_subtract(opnd1,opnd2,opnd1);
2091da177e4SLinus Torvalds Sgl_setzero(opnd3);
2101da177e4SLinus Torvalds for (count=1;count<=SGL_P && Sgl_all(opnd1);count++) {
2111da177e4SLinus Torvalds Sgl_leftshiftby1(opnd1);
2121da177e4SLinus Torvalds Sgl_leftshiftby1(opnd3);
2131da177e4SLinus Torvalds if (Sgl_iszero_sign(opnd1)) {
2141da177e4SLinus Torvalds Sgl_setone_lowmantissa(opnd3);
2151da177e4SLinus Torvalds Sgl_subtract(opnd1,opnd2,opnd1);
2161da177e4SLinus Torvalds }
2171da177e4SLinus Torvalds else Sgl_addition(opnd1,opnd2,opnd1);
2181da177e4SLinus Torvalds }
2191da177e4SLinus Torvalds if (count <= SGL_P) {
2201da177e4SLinus Torvalds Sgl_leftshiftby1(opnd3);
2211da177e4SLinus Torvalds Sgl_setone_lowmantissa(opnd3);
2221da177e4SLinus Torvalds Sgl_leftshift(opnd3,SGL_P-count);
2231da177e4SLinus Torvalds if (Sgl_iszero_hidden(opnd3)) {
2241da177e4SLinus Torvalds Sgl_leftshiftby1(opnd3);
2251da177e4SLinus Torvalds dest_exponent--;
2261da177e4SLinus Torvalds }
2271da177e4SLinus Torvalds }
2281da177e4SLinus Torvalds else {
2291da177e4SLinus Torvalds if (Sgl_iszero_hidden(opnd3)) {
2301da177e4SLinus Torvalds /* need to get one more bit of result */
2311da177e4SLinus Torvalds Sgl_leftshiftby1(opnd1);
2321da177e4SLinus Torvalds Sgl_leftshiftby1(opnd3);
2331da177e4SLinus Torvalds if (Sgl_iszero_sign(opnd1)) {
2341da177e4SLinus Torvalds Sgl_setone_lowmantissa(opnd3);
2351da177e4SLinus Torvalds Sgl_subtract(opnd1,opnd2,opnd1);
2361da177e4SLinus Torvalds }
2371da177e4SLinus Torvalds else Sgl_addition(opnd1,opnd2,opnd1);
2381da177e4SLinus Torvalds dest_exponent--;
2391da177e4SLinus Torvalds }
2401da177e4SLinus Torvalds if (Sgl_iszero_sign(opnd1)) guardbit = TRUE;
2411da177e4SLinus Torvalds stickybit = Sgl_all(opnd1);
2421da177e4SLinus Torvalds }
2431da177e4SLinus Torvalds inexact = guardbit | stickybit;
2441da177e4SLinus Torvalds
2451da177e4SLinus Torvalds /*
2461da177e4SLinus Torvalds * round result
2471da177e4SLinus Torvalds */
2481da177e4SLinus Torvalds if (inexact && (dest_exponent > 0 || Is_underflowtrap_enabled())) {
2491da177e4SLinus Torvalds Sgl_clear_signexponent(opnd3);
2501da177e4SLinus Torvalds switch (Rounding_mode()) {
2511da177e4SLinus Torvalds case ROUNDPLUS:
2521da177e4SLinus Torvalds if (Sgl_iszero_sign(result))
2531da177e4SLinus Torvalds Sgl_increment_mantissa(opnd3);
2541da177e4SLinus Torvalds break;
2551da177e4SLinus Torvalds case ROUNDMINUS:
2561da177e4SLinus Torvalds if (Sgl_isone_sign(result))
2571da177e4SLinus Torvalds Sgl_increment_mantissa(opnd3);
2581da177e4SLinus Torvalds break;
2591da177e4SLinus Torvalds case ROUNDNEAREST:
2601da177e4SLinus Torvalds if (guardbit) {
2611da177e4SLinus Torvalds if (stickybit || Sgl_isone_lowmantissa(opnd3))
2621da177e4SLinus Torvalds Sgl_increment_mantissa(opnd3);
2631da177e4SLinus Torvalds }
2641da177e4SLinus Torvalds }
2651da177e4SLinus Torvalds if (Sgl_isone_hidden(opnd3)) dest_exponent++;
2661da177e4SLinus Torvalds }
2671da177e4SLinus Torvalds Sgl_set_mantissa(result,opnd3);
2681da177e4SLinus Torvalds
2691da177e4SLinus Torvalds /*
2701da177e4SLinus Torvalds * Test for overflow
2711da177e4SLinus Torvalds */
2721da177e4SLinus Torvalds if (dest_exponent >= SGL_INFINITY_EXPONENT) {
2731da177e4SLinus Torvalds /* trap if OVERFLOWTRAP enabled */
2741da177e4SLinus Torvalds if (Is_overflowtrap_enabled()) {
2751da177e4SLinus Torvalds /*
2761da177e4SLinus Torvalds * Adjust bias of result
2771da177e4SLinus Torvalds */
2781da177e4SLinus Torvalds Sgl_setwrapped_exponent(result,dest_exponent,ovfl);
2791da177e4SLinus Torvalds *dstptr = result;
2801da177e4SLinus Torvalds if (inexact)
2811da177e4SLinus Torvalds if (Is_inexacttrap_enabled())
2821da177e4SLinus Torvalds return(OVERFLOWEXCEPTION | INEXACTEXCEPTION);
2831da177e4SLinus Torvalds else Set_inexactflag();
2841da177e4SLinus Torvalds return(OVERFLOWEXCEPTION);
2851da177e4SLinus Torvalds }
2861da177e4SLinus Torvalds Set_overflowflag();
2871da177e4SLinus Torvalds /* set result to infinity or largest number */
2881da177e4SLinus Torvalds Sgl_setoverflow(result);
2891da177e4SLinus Torvalds inexact = TRUE;
2901da177e4SLinus Torvalds }
2911da177e4SLinus Torvalds /*
2921da177e4SLinus Torvalds * Test for underflow
2931da177e4SLinus Torvalds */
2941da177e4SLinus Torvalds else if (dest_exponent <= 0) {
2951da177e4SLinus Torvalds /* trap if UNDERFLOWTRAP enabled */
2961da177e4SLinus Torvalds if (Is_underflowtrap_enabled()) {
2971da177e4SLinus Torvalds /*
2981da177e4SLinus Torvalds * Adjust bias of result
2991da177e4SLinus Torvalds */
3001da177e4SLinus Torvalds Sgl_setwrapped_exponent(result,dest_exponent,unfl);
3011da177e4SLinus Torvalds *dstptr = result;
3021da177e4SLinus Torvalds if (inexact)
3031da177e4SLinus Torvalds if (Is_inexacttrap_enabled())
3041da177e4SLinus Torvalds return(UNDERFLOWEXCEPTION | INEXACTEXCEPTION);
3051da177e4SLinus Torvalds else Set_inexactflag();
3061da177e4SLinus Torvalds return(UNDERFLOWEXCEPTION);
3071da177e4SLinus Torvalds }
3081da177e4SLinus Torvalds
3091da177e4SLinus Torvalds /* Determine if should set underflow flag */
3101da177e4SLinus Torvalds is_tiny = TRUE;
3111da177e4SLinus Torvalds if (dest_exponent == 0 && inexact) {
3121da177e4SLinus Torvalds switch (Rounding_mode()) {
3131da177e4SLinus Torvalds case ROUNDPLUS:
3141da177e4SLinus Torvalds if (Sgl_iszero_sign(result)) {
3151da177e4SLinus Torvalds Sgl_increment(opnd3);
3161da177e4SLinus Torvalds if (Sgl_isone_hiddenoverflow(opnd3))
3171da177e4SLinus Torvalds is_tiny = FALSE;
3181da177e4SLinus Torvalds Sgl_decrement(opnd3);
3191da177e4SLinus Torvalds }
3201da177e4SLinus Torvalds break;
3211da177e4SLinus Torvalds case ROUNDMINUS:
3221da177e4SLinus Torvalds if (Sgl_isone_sign(result)) {
3231da177e4SLinus Torvalds Sgl_increment(opnd3);
3241da177e4SLinus Torvalds if (Sgl_isone_hiddenoverflow(opnd3))
3251da177e4SLinus Torvalds is_tiny = FALSE;
3261da177e4SLinus Torvalds Sgl_decrement(opnd3);
3271da177e4SLinus Torvalds }
3281da177e4SLinus Torvalds break;
3291da177e4SLinus Torvalds case ROUNDNEAREST:
3301da177e4SLinus Torvalds if (guardbit && (stickybit ||
3311da177e4SLinus Torvalds Sgl_isone_lowmantissa(opnd3))) {
3321da177e4SLinus Torvalds Sgl_increment(opnd3);
3331da177e4SLinus Torvalds if (Sgl_isone_hiddenoverflow(opnd3))
3341da177e4SLinus Torvalds is_tiny = FALSE;
3351da177e4SLinus Torvalds Sgl_decrement(opnd3);
3361da177e4SLinus Torvalds }
3371da177e4SLinus Torvalds break;
3381da177e4SLinus Torvalds }
3391da177e4SLinus Torvalds }
3401da177e4SLinus Torvalds
3411da177e4SLinus Torvalds /*
3421da177e4SLinus Torvalds * denormalize result or set to signed zero
3431da177e4SLinus Torvalds */
3441da177e4SLinus Torvalds stickybit = inexact;
3451da177e4SLinus Torvalds Sgl_denormalize(opnd3,dest_exponent,guardbit,stickybit,inexact);
3461da177e4SLinus Torvalds
3471da177e4SLinus Torvalds /* return rounded number */
3481da177e4SLinus Torvalds if (inexact) {
3491da177e4SLinus Torvalds switch (Rounding_mode()) {
3501da177e4SLinus Torvalds case ROUNDPLUS:
3511da177e4SLinus Torvalds if (Sgl_iszero_sign(result)) {
3521da177e4SLinus Torvalds Sgl_increment(opnd3);
3531da177e4SLinus Torvalds }
3541da177e4SLinus Torvalds break;
3551da177e4SLinus Torvalds case ROUNDMINUS:
3561da177e4SLinus Torvalds if (Sgl_isone_sign(result)) {
3571da177e4SLinus Torvalds Sgl_increment(opnd3);
3581da177e4SLinus Torvalds }
3591da177e4SLinus Torvalds break;
3601da177e4SLinus Torvalds case ROUNDNEAREST:
3611da177e4SLinus Torvalds if (guardbit && (stickybit ||
3621da177e4SLinus Torvalds Sgl_isone_lowmantissa(opnd3))) {
3631da177e4SLinus Torvalds Sgl_increment(opnd3);
3641da177e4SLinus Torvalds }
3651da177e4SLinus Torvalds break;
3661da177e4SLinus Torvalds }
3671da177e4SLinus Torvalds if (is_tiny) Set_underflowflag();
3681da177e4SLinus Torvalds }
3691da177e4SLinus Torvalds Sgl_set_exponentmantissa(result,opnd3);
3701da177e4SLinus Torvalds }
3711da177e4SLinus Torvalds else Sgl_set_exponent(result,dest_exponent);
3721da177e4SLinus Torvalds *dstptr = result;
3731da177e4SLinus Torvalds /* check for inexact */
3741da177e4SLinus Torvalds if (inexact) {
3751da177e4SLinus Torvalds if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION);
3761da177e4SLinus Torvalds else Set_inexactflag();
3771da177e4SLinus Torvalds }
3781da177e4SLinus Torvalds return(NOEXCEPTION);
3791da177e4SLinus Torvalds }
380