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-rw-r--r--arch/parisc/math-emu/fmpyfadd.c2642
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diff --git a/arch/parisc/math-emu/fmpyfadd.c b/arch/parisc/math-emu/fmpyfadd.c
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+// 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/fmpyfadd.c $Revision: 1.1 $
+ *
+ * Purpose:
+ * Double Floating-point Multiply Fused Add
+ * Double Floating-point Multiply Negate Fused Add
+ * Single Floating-point Multiply Fused Add
+ * Single Floating-point Multiply Negate Fused Add
+ *
+ * External Interfaces:
+ * dbl_fmpyfadd(src1ptr,src2ptr,src3ptr,status,dstptr)
+ * dbl_fmpynfadd(src1ptr,src2ptr,src3ptr,status,dstptr)
+ * sgl_fmpyfadd(src1ptr,src2ptr,src3ptr,status,dstptr)
+ * sgl_fmpynfadd(src1ptr,src2ptr,src3ptr,status,dstptr)
+ *
+ * Internal Interfaces:
+ *
+ * Theory:
+ * <<please update with a overview of the operation of this file>>
+ *
+ * END_DESC
+*/
+
+
+#include "float.h"
+#include "sgl_float.h"
+#include "dbl_float.h"
+
+
+/*
+ * Double Floating-point Multiply Fused Add
+ */
+
+int
+dbl_fmpyfadd(
+ dbl_floating_point *src1ptr,
+ dbl_floating_point *src2ptr,
+ dbl_floating_point *src3ptr,
+ unsigned int *status,
+ dbl_floating_point *dstptr)
+{
+ unsigned int opnd1p1, opnd1p2, opnd2p1, opnd2p2, opnd3p1, opnd3p2;
+ register unsigned int tmpresp1, tmpresp2, tmpresp3, tmpresp4;
+ unsigned int rightp1, rightp2, rightp3, rightp4;
+ unsigned int resultp1, resultp2 = 0, resultp3 = 0, resultp4 = 0;
+ register int mpy_exponent, add_exponent, count;
+ boolean inexact = FALSE, is_tiny = FALSE;
+
+ unsigned int signlessleft1, signlessright1, save;
+ register int result_exponent, diff_exponent;
+ int sign_save, jumpsize;
+
+ Dbl_copyfromptr(src1ptr,opnd1p1,opnd1p2);
+ Dbl_copyfromptr(src2ptr,opnd2p1,opnd2p2);
+ Dbl_copyfromptr(src3ptr,opnd3p1,opnd3p2);
+
+ /*
+ * set sign bit of result of multiply
+ */
+ if (Dbl_sign(opnd1p1) ^ Dbl_sign(opnd2p1))
+ Dbl_setnegativezerop1(resultp1);
+ else Dbl_setzerop1(resultp1);
+
+ /*
+ * Generate multiply exponent
+ */
+ mpy_exponent = Dbl_exponent(opnd1p1) + Dbl_exponent(opnd2p1) - DBL_BIAS;
+
+ /*
+ * check first operand for NaN's or infinity
+ */
+ if (Dbl_isinfinity_exponent(opnd1p1)) {
+ if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) {
+ if (Dbl_isnotnan(opnd2p1,opnd2p2) &&
+ Dbl_isnotnan(opnd3p1,opnd3p2)) {
+ if (Dbl_iszero_exponentmantissa(opnd2p1,opnd2p2)) {
+ /*
+ * invalid since operands are infinity
+ * and zero
+ */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ Set_invalidflag();
+ Dbl_makequietnan(resultp1,resultp2);
+ Dbl_copytoptr(resultp1,resultp2,dstptr);
+ return(NOEXCEPTION);
+ }
+ /*
+ * Check third operand for infinity with a
+ * sign opposite of the multiply result
+ */
+ if (Dbl_isinfinity(opnd3p1,opnd3p2) &&
+ (Dbl_sign(resultp1) ^ Dbl_sign(opnd3p1))) {
+ /*
+ * invalid since attempting a magnitude
+ * subtraction of infinities
+ */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_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(OPC_2E_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(OPC_2E_INVALIDEXCEPTION);
+ /* make NaN quiet */
+ Set_invalidflag();
+ Dbl_set_quiet(opnd2p1);
+ Dbl_copytoptr(opnd2p1,opnd2p2,dstptr);
+ return(NOEXCEPTION);
+ }
+ /*
+ * is third operand a signaling NaN?
+ */
+ else if (Dbl_is_signalingnan(opnd3p1)) {
+ /* trap if INVALIDTRAP enabled */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ /* make NaN quiet */
+ Set_invalidflag();
+ Dbl_set_quiet(opnd3p1);
+ Dbl_copytoptr(opnd3p1,opnd3p2,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)) {
+ if (Dbl_isnotnan(opnd3p1,opnd3p2)) {
+ if (Dbl_iszero_exponentmantissa(opnd1p1,opnd1p2)) {
+ /*
+ * invalid since multiply operands are
+ * zero & infinity
+ */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ Set_invalidflag();
+ Dbl_makequietnan(opnd2p1,opnd2p2);
+ Dbl_copytoptr(opnd2p1,opnd2p2,dstptr);
+ return(NOEXCEPTION);
+ }
+
+ /*
+ * Check third operand for infinity with a
+ * sign opposite of the multiply result
+ */
+ if (Dbl_isinfinity(opnd3p1,opnd3p2) &&
+ (Dbl_sign(resultp1) ^ Dbl_sign(opnd3p1))) {
+ /*
+ * invalid since attempting a magnitude
+ * subtraction of infinities
+ */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_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(opnd2p1)) {
+ /* trap if INVALIDTRAP enabled */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ /* make NaN quiet */
+ Set_invalidflag();
+ Dbl_set_quiet(opnd2p1);
+ }
+ /*
+ * is third operand a signaling NaN?
+ */
+ else if (Dbl_is_signalingnan(opnd3p1)) {
+ /* trap if INVALIDTRAP enabled */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ /* make NaN quiet */
+ Set_invalidflag();
+ Dbl_set_quiet(opnd3p1);
+ Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
+ return(NOEXCEPTION);
+ }
+ /*
+ * return quiet NaN
+ */
+ Dbl_copytoptr(opnd2p1,opnd2p2,dstptr);
+ return(NOEXCEPTION);
+ }
+ }
+
+ /*
+ * check third operand for NaN's or infinity
+ */
+ if (Dbl_isinfinity_exponent(opnd3p1)) {
+ if (Dbl_iszero_mantissa(opnd3p1,opnd3p2)) {
+ /* return infinity */
+ Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
+ return(NOEXCEPTION);
+ } else {
+ /*
+ * is NaN; signaling or quiet?
+ */
+ if (Dbl_isone_signaling(opnd3p1)) {
+ /* trap if INVALIDTRAP enabled */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ /* make NaN quiet */
+ Set_invalidflag();
+ Dbl_set_quiet(opnd3p1);
+ }
+ /*
+ * return quiet NaN
+ */
+ Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
+ return(NOEXCEPTION);
+ }
+ }
+
+ /*
+ * Generate multiply 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)) {
+ /*
+ * Perform the add opnd3 with zero here.
+ */
+ if (Dbl_iszero_exponentmantissa(opnd3p1,opnd3p2)) {
+ if (Is_rounding_mode(ROUNDMINUS)) {
+ Dbl_or_signs(opnd3p1,resultp1);
+ } else {
+ Dbl_and_signs(opnd3p1,resultp1);
+ }
+ }
+ /*
+ * Now let's check for trapped underflow case.
+ */
+ else if (Dbl_iszero_exponent(opnd3p1) &&
+ Is_underflowtrap_enabled()) {
+ /* need to normalize results mantissa */
+ sign_save = Dbl_signextendedsign(opnd3p1);
+ result_exponent = 0;
+ Dbl_leftshiftby1(opnd3p1,opnd3p2);
+ Dbl_normalize(opnd3p1,opnd3p2,result_exponent);
+ Dbl_set_sign(opnd3p1,/*using*/sign_save);
+ Dbl_setwrapped_exponent(opnd3p1,result_exponent,
+ unfl);
+ Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
+ /* inexact = FALSE */
+ return(OPC_2E_UNDERFLOWEXCEPTION);
+ }
+ Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
+ return(NOEXCEPTION);
+ }
+ /* is denormalized, adjust exponent */
+ Dbl_clear_signexponent(opnd1p1);
+ Dbl_leftshiftby1(opnd1p1,opnd1p2);
+ Dbl_normalize(opnd1p1,opnd1p2,mpy_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 {
+ /* check for zero */
+ if (Dbl_iszero_mantissa(opnd2p1,opnd2p2)) {
+ /*
+ * Perform the add opnd3 with zero here.
+ */
+ if (Dbl_iszero_exponentmantissa(opnd3p1,opnd3p2)) {
+ if (Is_rounding_mode(ROUNDMINUS)) {
+ Dbl_or_signs(opnd3p1,resultp1);
+ } else {
+ Dbl_and_signs(opnd3p1,resultp1);
+ }
+ }
+ /*
+ * Now let's check for trapped underflow case.
+ */
+ else if (Dbl_iszero_exponent(opnd3p1) &&
+ Is_underflowtrap_enabled()) {
+ /* need to normalize results mantissa */
+ sign_save = Dbl_signextendedsign(opnd3p1);
+ result_exponent = 0;
+ Dbl_leftshiftby1(opnd3p1,opnd3p2);
+ Dbl_normalize(opnd3p1,opnd3p2,result_exponent);
+ Dbl_set_sign(opnd3p1,/*using*/sign_save);
+ Dbl_setwrapped_exponent(opnd3p1,result_exponent,
+ unfl);
+ Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
+ /* inexact = FALSE */
+ return(OPC_2E_UNDERFLOWEXCEPTION);
+ }
+ Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
+ return(NOEXCEPTION);
+ }
+ /* is denormalized; want to normalize */
+ Dbl_clear_signexponent(opnd2p1);
+ Dbl_leftshiftby1(opnd2p1,opnd2p2);
+ Dbl_normalize(opnd2p1,opnd2p2,mpy_exponent);
+ }
+
+ /* Multiply the first two source mantissas together */
+
+ /*
+ * The intermediate result will be kept in tmpres,
+ * which needs enough room for 106 bits of mantissa,
+ * so lets call it a Double extended.
+ */
+ Dblext_setzero(tmpresp1,tmpresp2,tmpresp3,tmpresp4);
+
+ /*
+ * Four bits at a time are inspected in each loop, and a
+ * simple shift and add multiply algorithm is used.
+ */
+ for (count = DBL_P-1; count >= 0; count -= 4) {
+ Dblext_rightshiftby4(tmpresp1,tmpresp2,tmpresp3,tmpresp4);
+ if (Dbit28p2(opnd1p2)) {
+ /* Fourword_add should be an ADD followed by 3 ADDC's */
+ Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4,
+ opnd2p1<<3 | opnd2p2>>29, opnd2p2<<3, 0, 0);
+ }
+ if (Dbit29p2(opnd1p2)) {
+ Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4,
+ opnd2p1<<2 | opnd2p2>>30, opnd2p2<<2, 0, 0);
+ }
+ if (Dbit30p2(opnd1p2)) {
+ Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4,
+ opnd2p1<<1 | opnd2p2>>31, opnd2p2<<1, 0, 0);
+ }
+ if (Dbit31p2(opnd1p2)) {
+ Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4,
+ opnd2p1, opnd2p2, 0, 0);
+ }
+ Dbl_rightshiftby4(opnd1p1,opnd1p2);
+ }
+ if (Is_dexthiddenoverflow(tmpresp1)) {
+ /* result mantissa >= 2 (mantissa overflow) */
+ mpy_exponent++;
+ Dblext_rightshiftby1(tmpresp1,tmpresp2,tmpresp3,tmpresp4);
+ }
+
+ /*
+ * Restore the sign of the mpy result which was saved in resultp1.
+ * The exponent will continue to be kept in mpy_exponent.
+ */
+ Dblext_set_sign(tmpresp1,Dbl_sign(resultp1));
+
+ /*
+ * No rounding is required, since the result of the multiply
+ * is exact in the extended format.
+ */
+
+ /*
+ * Now we are ready to perform the add portion of the operation.
+ *
+ * The exponents need to be kept as integers for now, since the
+ * multiply result might not fit into the exponent field. We
+ * can't overflow or underflow because of this yet, since the
+ * add could bring the final result back into range.
+ */
+ add_exponent = Dbl_exponent(opnd3p1);
+
+ /*
+ * Check for denormalized or zero add operand.
+ */
+ if (add_exponent == 0) {
+ /* check for zero */
+ if (Dbl_iszero_mantissa(opnd3p1,opnd3p2)) {
+ /* right is zero */
+ /* Left can't be zero and must be result.
+ *
+ * The final result is now in tmpres and mpy_exponent,
+ * and needs to be rounded and squeezed back into
+ * double precision format from double extended.
+ */
+ result_exponent = mpy_exponent;
+ Dblext_copy(tmpresp1,tmpresp2,tmpresp3,tmpresp4,
+ resultp1,resultp2,resultp3,resultp4);
+ sign_save = Dbl_signextendedsign(resultp1);/*save sign*/
+ goto round;
+ }
+
+ /*
+ * Neither are zeroes.
+ * Adjust exponent and normalize add operand.
+ */
+ sign_save = Dbl_signextendedsign(opnd3p1); /* save sign */
+ Dbl_clear_signexponent(opnd3p1);
+ Dbl_leftshiftby1(opnd3p1,opnd3p2);
+ Dbl_normalize(opnd3p1,opnd3p2,add_exponent);
+ Dbl_set_sign(opnd3p1,sign_save); /* restore sign */
+ } else {
+ Dbl_clear_exponent_set_hidden(opnd3p1);
+ }
+ /*
+ * Copy opnd3 to the double extended variable called right.
+ */
+ Dbl_copyto_dblext(opnd3p1,opnd3p2,rightp1,rightp2,rightp3,rightp4);
+
+ /*
+ * A zero "save" helps discover equal operands (for later),
+ * and is used in swapping operands (if needed).
+ */
+ Dblext_xortointp1(tmpresp1,rightp1,/*to*/save);
+
+ /*
+ * Compare magnitude of operands.
+ */
+ Dblext_copytoint_exponentmantissap1(tmpresp1,signlessleft1);
+ Dblext_copytoint_exponentmantissap1(rightp1,signlessright1);
+ if (mpy_exponent < add_exponent || mpy_exponent == add_exponent &&
+ Dblext_ismagnitudeless(tmpresp2,rightp2,signlessleft1,signlessright1)){
+ /*
+ * Set the left operand to the larger one by XOR swap.
+ * First finish the first word "save".
+ */
+ Dblext_xorfromintp1(save,rightp1,/*to*/rightp1);
+ Dblext_xorfromintp1(save,tmpresp1,/*to*/tmpresp1);
+ Dblext_swap_lower(tmpresp2,tmpresp3,tmpresp4,
+ rightp2,rightp3,rightp4);
+ /* also setup exponents used in rest of routine */
+ diff_exponent = add_exponent - mpy_exponent;
+ result_exponent = add_exponent;
+ } else {
+ /* also setup exponents used in rest of routine */
+ diff_exponent = mpy_exponent - add_exponent;
+ result_exponent = mpy_exponent;
+ }
+ /* Invariant: left is not smaller than right. */
+
+ /*
+ * Special case alignment of operands that would force alignment
+ * beyond the extent of the extension. A further optimization
+ * could special case this but only reduces the path length for
+ * this infrequent case.
+ */
+ if (diff_exponent > DBLEXT_THRESHOLD) {
+ diff_exponent = DBLEXT_THRESHOLD;
+ }
+
+ /* Align right operand by shifting it to the right */
+ Dblext_clear_sign(rightp1);
+ Dblext_right_align(rightp1,rightp2,rightp3,rightp4,
+ /*shifted by*/diff_exponent);
+
+ /* Treat sum and difference of the operands separately. */
+ if ((int)save < 0) {
+ /*
+ * Difference of the two operands. Overflow can occur if the
+ * multiply overflowed. A borrow can occur out of the hidden
+ * bit and force a post normalization phase.
+ */
+ Dblext_subtract(tmpresp1,tmpresp2,tmpresp3,tmpresp4,
+ rightp1,rightp2,rightp3,rightp4,
+ resultp1,resultp2,resultp3,resultp4);
+ sign_save = Dbl_signextendedsign(resultp1);
+ if (Dbl_iszero_hidden(resultp1)) {
+ /* Handle normalization */
+ /* A straightforward algorithm would now shift the
+ * result and extension left until the hidden bit
+ * becomes one. Not all of the extension bits need
+ * participate in the shift. Only the two most
+ * significant bits (round and guard) are needed.
+ * If only a single shift is needed then the guard
+ * bit becomes a significant low order bit and the
+ * extension must participate in the rounding.
+ * If more than a single shift is needed, then all
+ * bits to the right of the guard bit are zeros,
+ * and the guard bit may or may not be zero. */
+ Dblext_leftshiftby1(resultp1,resultp2,resultp3,
+ resultp4);
+
+ /* Need to check for a zero result. The sign and
+ * exponent fields have already been zeroed. The more
+ * efficient test of the full object can be used.
+ */
+ if(Dblext_iszero(resultp1,resultp2,resultp3,resultp4)){
+ /* Must have been "x-x" or "x+(-x)". */
+ if (Is_rounding_mode(ROUNDMINUS))
+ Dbl_setone_sign(resultp1);
+ Dbl_copytoptr(resultp1,resultp2,dstptr);
+ return(NOEXCEPTION);
+ }
+ result_exponent--;
+
+ /* Look to see if normalization is finished. */
+ if (Dbl_isone_hidden(resultp1)) {
+ /* No further normalization is needed */
+ goto round;
+ }
+
+ /* Discover first one bit to determine shift amount.
+ * Use a modified binary search. We have already
+ * shifted the result one position right and still
+ * not found a one so the remainder of the extension
+ * must be zero and simplifies rounding. */
+ /* Scan bytes */
+ while (Dbl_iszero_hiddenhigh7mantissa(resultp1)) {
+ Dblext_leftshiftby8(resultp1,resultp2,resultp3,resultp4);
+ result_exponent -= 8;
+ }
+ /* Now narrow it down to the nibble */
+ if (Dbl_iszero_hiddenhigh3mantissa(resultp1)) {
+ /* The lower nibble contains the
+ * normalizing one */
+ Dblext_leftshiftby4(resultp1,resultp2,resultp3,resultp4);
+ result_exponent -= 4;
+ }
+ /* Select case where first bit is set (already
+ * normalized) otherwise select the proper shift. */
+ jumpsize = Dbl_hiddenhigh3mantissa(resultp1);
+ if (jumpsize <= 7) switch(jumpsize) {
+ case 1:
+ Dblext_leftshiftby3(resultp1,resultp2,resultp3,
+ resultp4);
+ result_exponent -= 3;
+ break;
+ case 2:
+ case 3:
+ Dblext_leftshiftby2(resultp1,resultp2,resultp3,
+ resultp4);
+ result_exponent -= 2;
+ break;
+ case 4:
+ case 5:
+ case 6:
+ case 7:
+ Dblext_leftshiftby1(resultp1,resultp2,resultp3,
+ resultp4);
+ result_exponent -= 1;
+ break;
+ }
+ } /* end if (hidden...)... */
+ /* Fall through and round */
+ } /* end if (save < 0)... */
+ else {
+ /* Add magnitudes */
+ Dblext_addition(tmpresp1,tmpresp2,tmpresp3,tmpresp4,
+ rightp1,rightp2,rightp3,rightp4,
+ /*to*/resultp1,resultp2,resultp3,resultp4);
+ sign_save = Dbl_signextendedsign(resultp1);
+ if (Dbl_isone_hiddenoverflow(resultp1)) {
+ /* Prenormalization required. */
+ Dblext_arithrightshiftby1(resultp1,resultp2,resultp3,
+ resultp4);
+ result_exponent++;
+ } /* end if hiddenoverflow... */
+ } /* end else ...add magnitudes... */
+
+ /* Round the result. If the extension and lower two words are
+ * all zeros, then the result is exact. Otherwise round in the
+ * correct direction. Underflow is possible. If a postnormalization
+ * is necessary, then the mantissa is all zeros so no shift is needed.
+ */
+ round:
+ if (result_exponent <= 0 && !Is_underflowtrap_enabled()) {
+ Dblext_denormalize(resultp1,resultp2,resultp3,resultp4,
+ result_exponent,is_tiny);
+ }
+ Dbl_set_sign(resultp1,/*using*/sign_save);
+ if (Dblext_isnotzero_mantissap3(resultp3) ||
+ Dblext_isnotzero_mantissap4(resultp4)) {
+ inexact = TRUE;
+ switch(Rounding_mode()) {
+ case ROUNDNEAREST: /* The default. */
+ if (Dblext_isone_highp3(resultp3)) {
+ /* at least 1/2 ulp */
+ if (Dblext_isnotzero_low31p3(resultp3) ||
+ Dblext_isnotzero_mantissap4(resultp4) ||
+ Dblext_isone_lowp2(resultp2)) {
+ /* either exactly half way and odd or
+ * more than 1/2ulp */
+ Dbl_increment(resultp1,resultp2);
+ }
+ }
+ break;
+
+ case ROUNDPLUS:
+ if (Dbl_iszero_sign(resultp1)) {
+ /* Round up positive results */
+ Dbl_increment(resultp1,resultp2);
+ }
+ break;
+
+ case ROUNDMINUS:
+ if (Dbl_isone_sign(resultp1)) {
+ /* Round down negative results */
+ Dbl_increment(resultp1,resultp2);
+ }
+
+ case ROUNDZERO:;
+ /* truncate is simple */
+ } /* end switch... */
+ if (Dbl_isone_hiddenoverflow(resultp1)) result_exponent++;
+ }
+ if (result_exponent >= DBL_INFINITY_EXPONENT) {
+ /* trap if OVERFLOWTRAP enabled */
+ if (Is_overflowtrap_enabled()) {
+ /*
+ * Adjust bias of result
+ */
+ Dbl_setwrapped_exponent(resultp1,result_exponent,ovfl);
+ Dbl_copytoptr(resultp1,resultp2,dstptr);
+ if (inexact)
+ if (Is_inexacttrap_enabled())
+ return (OPC_2E_OVERFLOWEXCEPTION |
+ OPC_2E_INEXACTEXCEPTION);
+ else Set_inexactflag();
+ return (OPC_2E_OVERFLOWEXCEPTION);
+ }
+ inexact = TRUE;
+ Set_overflowflag();
+ /* set result to infinity or largest number */
+ Dbl_setoverflow(resultp1,resultp2);
+
+ } else if (result_exponent <= 0) { /* underflow case */
+ if (Is_underflowtrap_enabled()) {
+ /*
+ * Adjust bias of result
+ */
+ Dbl_setwrapped_exponent(resultp1,result_exponent,unfl);
+ Dbl_copytoptr(resultp1,resultp2,dstptr);
+ if (inexact)
+ if (Is_inexacttrap_enabled())
+ return (OPC_2E_UNDERFLOWEXCEPTION |
+ OPC_2E_INEXACTEXCEPTION);
+ else Set_inexactflag();
+ return(OPC_2E_UNDERFLOWEXCEPTION);
+ }
+ else if (inexact && is_tiny) Set_underflowflag();
+ }
+ else Dbl_set_exponent(resultp1,result_exponent);
+ Dbl_copytoptr(resultp1,resultp2,dstptr);
+ if (inexact)
+ if (Is_inexacttrap_enabled()) return(OPC_2E_INEXACTEXCEPTION);
+ else Set_inexactflag();
+ return(NOEXCEPTION);
+}
+
+/*
+ * Double Floating-point Multiply Negate Fused Add
+ */
+
+dbl_fmpynfadd(src1ptr,src2ptr,src3ptr,status,dstptr)
+
+dbl_floating_point *src1ptr, *src2ptr, *src3ptr, *dstptr;
+unsigned int *status;
+{
+ unsigned int opnd1p1, opnd1p2, opnd2p1, opnd2p2, opnd3p1, opnd3p2;
+ register unsigned int tmpresp1, tmpresp2, tmpresp3, tmpresp4;
+ unsigned int rightp1, rightp2, rightp3, rightp4;
+ unsigned int resultp1, resultp2 = 0, resultp3 = 0, resultp4 = 0;
+ register int mpy_exponent, add_exponent, count;
+ boolean inexact = FALSE, is_tiny = FALSE;
+
+ unsigned int signlessleft1, signlessright1, save;
+ register int result_exponent, diff_exponent;
+ int sign_save, jumpsize;
+
+ Dbl_copyfromptr(src1ptr,opnd1p1,opnd1p2);
+ Dbl_copyfromptr(src2ptr,opnd2p1,opnd2p2);
+ Dbl_copyfromptr(src3ptr,opnd3p1,opnd3p2);
+
+ /*
+ * set sign bit of result of multiply
+ */
+ if (Dbl_sign(opnd1p1) ^ Dbl_sign(opnd2p1))
+ Dbl_setzerop1(resultp1);
+ else
+ Dbl_setnegativezerop1(resultp1);
+
+ /*
+ * Generate multiply exponent
+ */
+ mpy_exponent = Dbl_exponent(opnd1p1) + Dbl_exponent(opnd2p1) - DBL_BIAS;
+
+ /*
+ * check first operand for NaN's or infinity
+ */
+ if (Dbl_isinfinity_exponent(opnd1p1)) {
+ if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) {
+ if (Dbl_isnotnan(opnd2p1,opnd2p2) &&
+ Dbl_isnotnan(opnd3p1,opnd3p2)) {
+ if (Dbl_iszero_exponentmantissa(opnd2p1,opnd2p2)) {
+ /*
+ * invalid since operands are infinity
+ * and zero
+ */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ Set_invalidflag();
+ Dbl_makequietnan(resultp1,resultp2);
+ Dbl_copytoptr(resultp1,resultp2,dstptr);
+ return(NOEXCEPTION);
+ }
+ /*
+ * Check third operand for infinity with a
+ * sign opposite of the multiply result
+ */
+ if (Dbl_isinfinity(opnd3p1,opnd3p2) &&
+ (Dbl_sign(resultp1) ^ Dbl_sign(opnd3p1))) {
+ /*
+ * invalid since attempting a magnitude
+ * subtraction of infinities
+ */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_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(OPC_2E_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(OPC_2E_INVALIDEXCEPTION);
+ /* make NaN quiet */
+ Set_invalidflag();
+ Dbl_set_quiet(opnd2p1);
+ Dbl_copytoptr(opnd2p1,opnd2p2,dstptr);
+ return(NOEXCEPTION);
+ }
+ /*
+ * is third operand a signaling NaN?
+ */
+ else if (Dbl_is_signalingnan(opnd3p1)) {
+ /* trap if INVALIDTRAP enabled */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ /* make NaN quiet */
+ Set_invalidflag();
+ Dbl_set_quiet(opnd3p1);
+ Dbl_copytoptr(opnd3p1,opnd3p2,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)) {
+ if (Dbl_isnotnan(opnd3p1,opnd3p2)) {
+ if (Dbl_iszero_exponentmantissa(opnd1p1,opnd1p2)) {
+ /*
+ * invalid since multiply operands are
+ * zero & infinity
+ */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ Set_invalidflag();
+ Dbl_makequietnan(opnd2p1,opnd2p2);
+ Dbl_copytoptr(opnd2p1,opnd2p2,dstptr);
+ return(NOEXCEPTION);
+ }
+
+ /*
+ * Check third operand for infinity with a
+ * sign opposite of the multiply result
+ */
+ if (Dbl_isinfinity(opnd3p1,opnd3p2) &&
+ (Dbl_sign(resultp1) ^ Dbl_sign(opnd3p1))) {
+ /*
+ * invalid since attempting a magnitude
+ * subtraction of infinities
+ */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_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(opnd2p1)) {
+ /* trap if INVALIDTRAP enabled */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ /* make NaN quiet */
+ Set_invalidflag();
+ Dbl_set_quiet(opnd2p1);
+ }
+ /*
+ * is third operand a signaling NaN?
+ */
+ else if (Dbl_is_signalingnan(opnd3p1)) {
+ /* trap if INVALIDTRAP enabled */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ /* make NaN quiet */
+ Set_invalidflag();
+ Dbl_set_quiet(opnd3p1);
+ Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
+ return(NOEXCEPTION);
+ }
+ /*
+ * return quiet NaN
+ */
+ Dbl_copytoptr(opnd2p1,opnd2p2,dstptr);
+ return(NOEXCEPTION);
+ }
+ }
+
+ /*
+ * check third operand for NaN's or infinity
+ */
+ if (Dbl_isinfinity_exponent(opnd3p1)) {
+ if (Dbl_iszero_mantissa(opnd3p1,opnd3p2)) {
+ /* return infinity */
+ Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
+ return(NOEXCEPTION);
+ } else {
+ /*
+ * is NaN; signaling or quiet?
+ */
+ if (Dbl_isone_signaling(opnd3p1)) {
+ /* trap if INVALIDTRAP enabled */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ /* make NaN quiet */
+ Set_invalidflag();
+ Dbl_set_quiet(opnd3p1);
+ }
+ /*
+ * return quiet NaN
+ */
+ Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
+ return(NOEXCEPTION);
+ }
+ }
+
+ /*
+ * Generate multiply 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)) {
+ /*
+ * Perform the add opnd3 with zero here.
+ */
+ if (Dbl_iszero_exponentmantissa(opnd3p1,opnd3p2)) {
+ if (Is_rounding_mode(ROUNDMINUS)) {
+ Dbl_or_signs(opnd3p1,resultp1);
+ } else {
+ Dbl_and_signs(opnd3p1,resultp1);
+ }
+ }
+ /*
+ * Now let's check for trapped underflow case.
+ */
+ else if (Dbl_iszero_exponent(opnd3p1) &&
+ Is_underflowtrap_enabled()) {
+ /* need to normalize results mantissa */
+ sign_save = Dbl_signextendedsign(opnd3p1);
+ result_exponent = 0;
+ Dbl_leftshiftby1(opnd3p1,opnd3p2);
+ Dbl_normalize(opnd3p1,opnd3p2,result_exponent);
+ Dbl_set_sign(opnd3p1,/*using*/sign_save);
+ Dbl_setwrapped_exponent(opnd3p1,result_exponent,
+ unfl);
+ Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
+ /* inexact = FALSE */
+ return(OPC_2E_UNDERFLOWEXCEPTION);
+ }
+ Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
+ return(NOEXCEPTION);
+ }
+ /* is denormalized, adjust exponent */
+ Dbl_clear_signexponent(opnd1p1);
+ Dbl_leftshiftby1(opnd1p1,opnd1p2);
+ Dbl_normalize(opnd1p1,opnd1p2,mpy_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 {
+ /* check for zero */
+ if (Dbl_iszero_mantissa(opnd2p1,opnd2p2)) {
+ /*
+ * Perform the add opnd3 with zero here.
+ */
+ if (Dbl_iszero_exponentmantissa(opnd3p1,opnd3p2)) {
+ if (Is_rounding_mode(ROUNDMINUS)) {
+ Dbl_or_signs(opnd3p1,resultp1);
+ } else {
+ Dbl_and_signs(opnd3p1,resultp1);
+ }
+ }
+ /*
+ * Now let's check for trapped underflow case.
+ */
+ else if (Dbl_iszero_exponent(opnd3p1) &&
+ Is_underflowtrap_enabled()) {
+ /* need to normalize results mantissa */
+ sign_save = Dbl_signextendedsign(opnd3p1);
+ result_exponent = 0;
+ Dbl_leftshiftby1(opnd3p1,opnd3p2);
+ Dbl_normalize(opnd3p1,opnd3p2,result_exponent);
+ Dbl_set_sign(opnd3p1,/*using*/sign_save);
+ Dbl_setwrapped_exponent(opnd3p1,result_exponent,
+ unfl);
+ Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
+ /* inexact = FALSE */
+ return(OPC_2E_UNDERFLOWEXCEPTION);
+ }
+ Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
+ return(NOEXCEPTION);
+ }
+ /* is denormalized; want to normalize */
+ Dbl_clear_signexponent(opnd2p1);
+ Dbl_leftshiftby1(opnd2p1,opnd2p2);
+ Dbl_normalize(opnd2p1,opnd2p2,mpy_exponent);
+ }
+
+ /* Multiply the first two source mantissas together */
+
+ /*
+ * The intermediate result will be kept in tmpres,
+ * which needs enough room for 106 bits of mantissa,
+ * so lets call it a Double extended.
+ */
+ Dblext_setzero(tmpresp1,tmpresp2,tmpresp3,tmpresp4);
+
+ /*
+ * Four bits at a time are inspected in each loop, and a
+ * simple shift and add multiply algorithm is used.
+ */
+ for (count = DBL_P-1; count >= 0; count -= 4) {
+ Dblext_rightshiftby4(tmpresp1,tmpresp2,tmpresp3,tmpresp4);
+ if (Dbit28p2(opnd1p2)) {
+ /* Fourword_add should be an ADD followed by 3 ADDC's */
+ Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4,
+ opnd2p1<<3 | opnd2p2>>29, opnd2p2<<3, 0, 0);
+ }
+ if (Dbit29p2(opnd1p2)) {
+ Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4,
+ opnd2p1<<2 | opnd2p2>>30, opnd2p2<<2, 0, 0);
+ }
+ if (Dbit30p2(opnd1p2)) {
+ Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4,
+ opnd2p1<<1 | opnd2p2>>31, opnd2p2<<1, 0, 0);
+ }
+ if (Dbit31p2(opnd1p2)) {
+ Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4,
+ opnd2p1, opnd2p2, 0, 0);
+ }
+ Dbl_rightshiftby4(opnd1p1,opnd1p2);
+ }
+ if (Is_dexthiddenoverflow(tmpresp1)) {
+ /* result mantissa >= 2 (mantissa overflow) */
+ mpy_exponent++;
+ Dblext_rightshiftby1(tmpresp1,tmpresp2,tmpresp3,tmpresp4);
+ }
+
+ /*
+ * Restore the sign of the mpy result which was saved in resultp1.
+ * The exponent will continue to be kept in mpy_exponent.
+ */
+ Dblext_set_sign(tmpresp1,Dbl_sign(resultp1));
+
+ /*
+ * No rounding is required, since the result of the multiply
+ * is exact in the extended format.
+ */
+
+ /*
+ * Now we are ready to perform the add portion of the operation.
+ *
+ * The exponents need to be kept as integers for now, since the
+ * multiply result might not fit into the exponent field. We
+ * can't overflow or underflow because of this yet, since the
+ * add could bring the final result back into range.
+ */
+ add_exponent = Dbl_exponent(opnd3p1);
+
+ /*
+ * Check for denormalized or zero add operand.
+ */
+ if (add_exponent == 0) {
+ /* check for zero */
+ if (Dbl_iszero_mantissa(opnd3p1,opnd3p2)) {
+ /* right is zero */
+ /* Left can't be zero and must be result.
+ *
+ * The final result is now in tmpres and mpy_exponent,
+ * and needs to be rounded and squeezed back into
+ * double precision format from double extended.
+ */
+ result_exponent = mpy_exponent;
+ Dblext_copy(tmpresp1,tmpresp2,tmpresp3,tmpresp4,
+ resultp1,resultp2,resultp3,resultp4);
+ sign_save = Dbl_signextendedsign(resultp1);/*save sign*/
+ goto round;
+ }
+
+ /*
+ * Neither are zeroes.
+ * Adjust exponent and normalize add operand.
+ */
+ sign_save = Dbl_signextendedsign(opnd3p1); /* save sign */
+ Dbl_clear_signexponent(opnd3p1);
+ Dbl_leftshiftby1(opnd3p1,opnd3p2);
+ Dbl_normalize(opnd3p1,opnd3p2,add_exponent);
+ Dbl_set_sign(opnd3p1,sign_save); /* restore sign */
+ } else {
+ Dbl_clear_exponent_set_hidden(opnd3p1);
+ }
+ /*
+ * Copy opnd3 to the double extended variable called right.
+ */
+ Dbl_copyto_dblext(opnd3p1,opnd3p2,rightp1,rightp2,rightp3,rightp4);
+
+ /*
+ * A zero "save" helps discover equal operands (for later),
+ * and is used in swapping operands (if needed).
+ */
+ Dblext_xortointp1(tmpresp1,rightp1,/*to*/save);
+
+ /*
+ * Compare magnitude of operands.
+ */
+ Dblext_copytoint_exponentmantissap1(tmpresp1,signlessleft1);
+ Dblext_copytoint_exponentmantissap1(rightp1,signlessright1);
+ if (mpy_exponent < add_exponent || mpy_exponent == add_exponent &&
+ Dblext_ismagnitudeless(tmpresp2,rightp2,signlessleft1,signlessright1)){
+ /*
+ * Set the left operand to the larger one by XOR swap.
+ * First finish the first word "save".
+ */
+ Dblext_xorfromintp1(save,rightp1,/*to*/rightp1);
+ Dblext_xorfromintp1(save,tmpresp1,/*to*/tmpresp1);
+ Dblext_swap_lower(tmpresp2,tmpresp3,tmpresp4,
+ rightp2,rightp3,rightp4);
+ /* also setup exponents used in rest of routine */
+ diff_exponent = add_exponent - mpy_exponent;
+ result_exponent = add_exponent;
+ } else {
+ /* also setup exponents used in rest of routine */
+ diff_exponent = mpy_exponent - add_exponent;
+ result_exponent = mpy_exponent;
+ }
+ /* Invariant: left is not smaller than right. */
+
+ /*
+ * Special case alignment of operands that would force alignment
+ * beyond the extent of the extension. A further optimization
+ * could special case this but only reduces the path length for
+ * this infrequent case.
+ */
+ if (diff_exponent > DBLEXT_THRESHOLD) {
+ diff_exponent = DBLEXT_THRESHOLD;
+ }
+
+ /* Align right operand by shifting it to the right */
+ Dblext_clear_sign(rightp1);
+ Dblext_right_align(rightp1,rightp2,rightp3,rightp4,
+ /*shifted by*/diff_exponent);
+
+ /* Treat sum and difference of the operands separately. */
+ if ((int)save < 0) {
+ /*
+ * Difference of the two operands. Overflow can occur if the
+ * multiply overflowed. A borrow can occur out of the hidden
+ * bit and force a post normalization phase.
+ */
+ Dblext_subtract(tmpresp1,tmpresp2,tmpresp3,tmpresp4,
+ rightp1,rightp2,rightp3,rightp4,
+ resultp1,resultp2,resultp3,resultp4);
+ sign_save = Dbl_signextendedsign(resultp1);
+ if (Dbl_iszero_hidden(resultp1)) {
+ /* Handle normalization */
+ /* A straightforward algorithm would now shift the
+ * result and extension left until the hidden bit
+ * becomes one. Not all of the extension bits need
+ * participate in the shift. Only the two most
+ * significant bits (round and guard) are needed.
+ * If only a single shift is needed then the guard
+ * bit becomes a significant low order bit and the
+ * extension must participate in the rounding.
+ * If more than a single shift is needed, then all
+ * bits to the right of the guard bit are zeros,
+ * and the guard bit may or may not be zero. */
+ Dblext_leftshiftby1(resultp1,resultp2,resultp3,
+ resultp4);
+
+ /* Need to check for a zero result. The sign and
+ * exponent fields have already been zeroed. The more
+ * efficient test of the full object can be used.
+ */
+ if (Dblext_iszero(resultp1,resultp2,resultp3,resultp4)) {
+ /* Must have been "x-x" or "x+(-x)". */
+ if (Is_rounding_mode(ROUNDMINUS))
+ Dbl_setone_sign(resultp1);
+ Dbl_copytoptr(resultp1,resultp2,dstptr);
+ return(NOEXCEPTION);
+ }
+ result_exponent--;
+
+ /* Look to see if normalization is finished. */
+ if (Dbl_isone_hidden(resultp1)) {
+ /* No further normalization is needed */
+ goto round;
+ }
+
+ /* Discover first one bit to determine shift amount.
+ * Use a modified binary search. We have already
+ * shifted the result one position right and still
+ * not found a one so the remainder of the extension
+ * must be zero and simplifies rounding. */
+ /* Scan bytes */
+ while (Dbl_iszero_hiddenhigh7mantissa(resultp1)) {
+ Dblext_leftshiftby8(resultp1,resultp2,resultp3,resultp4);
+ result_exponent -= 8;
+ }
+ /* Now narrow it down to the nibble */
+ if (Dbl_iszero_hiddenhigh3mantissa(resultp1)) {
+ /* The lower nibble contains the
+ * normalizing one */
+ Dblext_leftshiftby4(resultp1,resultp2,resultp3,resultp4);
+ result_exponent -= 4;
+ }
+ /* Select case where first bit is set (already
+ * normalized) otherwise select the proper shift. */
+ jumpsize = Dbl_hiddenhigh3mantissa(resultp1);
+ if (jumpsize <= 7) switch(jumpsize) {
+ case 1:
+ Dblext_leftshiftby3(resultp1,resultp2,resultp3,
+ resultp4);
+ result_exponent -= 3;
+ break;
+ case 2:
+ case 3:
+ Dblext_leftshiftby2(resultp1,resultp2,resultp3,
+ resultp4);
+ result_exponent -= 2;
+ break;
+ case 4:
+ case 5:
+ case 6:
+ case 7:
+ Dblext_leftshiftby1(resultp1,resultp2,resultp3,
+ resultp4);
+ result_exponent -= 1;
+ break;
+ }
+ } /* end if (hidden...)... */
+ /* Fall through and round */
+ } /* end if (save < 0)... */
+ else {
+ /* Add magnitudes */
+ Dblext_addition(tmpresp1,tmpresp2,tmpresp3,tmpresp4,
+ rightp1,rightp2,rightp3,rightp4,
+ /*to*/resultp1,resultp2,resultp3,resultp4);
+ sign_save = Dbl_signextendedsign(resultp1);
+ if (Dbl_isone_hiddenoverflow(resultp1)) {
+ /* Prenormalization required. */
+ Dblext_arithrightshiftby1(resultp1,resultp2,resultp3,
+ resultp4);
+ result_exponent++;
+ } /* end if hiddenoverflow... */
+ } /* end else ...add magnitudes... */
+
+ /* Round the result. If the extension and lower two words are
+ * all zeros, then the result is exact. Otherwise round in the
+ * correct direction. Underflow is possible. If a postnormalization
+ * is necessary, then the mantissa is all zeros so no shift is needed.
+ */
+ round:
+ if (result_exponent <= 0 && !Is_underflowtrap_enabled()) {
+ Dblext_denormalize(resultp1,resultp2,resultp3,resultp4,
+ result_exponent,is_tiny);
+ }
+ Dbl_set_sign(resultp1,/*using*/sign_save);
+ if (Dblext_isnotzero_mantissap3(resultp3) ||
+ Dblext_isnotzero_mantissap4(resultp4)) {
+ inexact = TRUE;
+ switch(Rounding_mode()) {
+ case ROUNDNEAREST: /* The default. */
+ if (Dblext_isone_highp3(resultp3)) {
+ /* at least 1/2 ulp */
+ if (Dblext_isnotzero_low31p3(resultp3) ||
+ Dblext_isnotzero_mantissap4(resultp4) ||
+ Dblext_isone_lowp2(resultp2)) {
+ /* either exactly half way and odd or
+ * more than 1/2ulp */
+ Dbl_increment(resultp1,resultp2);
+ }
+ }
+ break;
+
+ case ROUNDPLUS:
+ if (Dbl_iszero_sign(resultp1)) {
+ /* Round up positive results */
+ Dbl_increment(resultp1,resultp2);
+ }
+ break;
+
+ case ROUNDMINUS:
+ if (Dbl_isone_sign(resultp1)) {
+ /* Round down negative results */
+ Dbl_increment(resultp1,resultp2);
+ }
+
+ case ROUNDZERO:;
+ /* truncate is simple */
+ } /* end switch... */
+ if (Dbl_isone_hiddenoverflow(resultp1)) result_exponent++;
+ }
+ if (result_exponent >= DBL_INFINITY_EXPONENT) {
+ /* Overflow */
+ if (Is_overflowtrap_enabled()) {
+ /*
+ * Adjust bias of result
+ */
+ Dbl_setwrapped_exponent(resultp1,result_exponent,ovfl);
+ Dbl_copytoptr(resultp1,resultp2,dstptr);
+ if (inexact)
+ if (Is_inexacttrap_enabled())
+ return (OPC_2E_OVERFLOWEXCEPTION |
+ OPC_2E_INEXACTEXCEPTION);
+ else Set_inexactflag();
+ return (OPC_2E_OVERFLOWEXCEPTION);
+ }
+ inexact = TRUE;
+ Set_overflowflag();
+ Dbl_setoverflow(resultp1,resultp2);
+ } else if (result_exponent <= 0) { /* underflow case */
+ if (Is_underflowtrap_enabled()) {
+ /*
+ * Adjust bias of result
+ */
+ Dbl_setwrapped_exponent(resultp1,result_exponent,unfl);
+ Dbl_copytoptr(resultp1,resultp2,dstptr);
+ if (inexact)
+ if (Is_inexacttrap_enabled())
+ return (OPC_2E_UNDERFLOWEXCEPTION |
+ OPC_2E_INEXACTEXCEPTION);
+ else Set_inexactflag();
+ return(OPC_2E_UNDERFLOWEXCEPTION);
+ }
+ else if (inexact && is_tiny) Set_underflowflag();
+ }
+ else Dbl_set_exponent(resultp1,result_exponent);
+ Dbl_copytoptr(resultp1,resultp2,dstptr);
+ if (inexact)
+ if (Is_inexacttrap_enabled()) return(OPC_2E_INEXACTEXCEPTION);
+ else Set_inexactflag();
+ return(NOEXCEPTION);
+}
+
+/*
+ * Single Floating-point Multiply Fused Add
+ */
+
+sgl_fmpyfadd(src1ptr,src2ptr,src3ptr,status,dstptr)
+
+sgl_floating_point *src1ptr, *src2ptr, *src3ptr, *dstptr;
+unsigned int *status;
+{
+ unsigned int opnd1, opnd2, opnd3;
+ register unsigned int tmpresp1, tmpresp2;
+ unsigned int rightp1, rightp2;
+ unsigned int resultp1, resultp2 = 0;
+ register int mpy_exponent, add_exponent, count;
+ boolean inexact = FALSE, is_tiny = FALSE;
+
+ unsigned int signlessleft1, signlessright1, save;
+ register int result_exponent, diff_exponent;
+ int sign_save, jumpsize;
+
+ Sgl_copyfromptr(src1ptr,opnd1);
+ Sgl_copyfromptr(src2ptr,opnd2);
+ Sgl_copyfromptr(src3ptr,opnd3);
+
+ /*
+ * set sign bit of result of multiply
+ */
+ if (Sgl_sign(opnd1) ^ Sgl_sign(opnd2))
+ Sgl_setnegativezero(resultp1);
+ else Sgl_setzero(resultp1);
+
+ /*
+ * Generate multiply exponent
+ */
+ mpy_exponent = Sgl_exponent(opnd1) + Sgl_exponent(opnd2) - SGL_BIAS;
+
+ /*
+ * check first operand for NaN's or infinity
+ */
+ if (Sgl_isinfinity_exponent(opnd1)) {
+ if (Sgl_iszero_mantissa(opnd1)) {
+ if (Sgl_isnotnan(opnd2) && Sgl_isnotnan(opnd3)) {
+ if (Sgl_iszero_exponentmantissa(opnd2)) {
+ /*
+ * invalid since operands are infinity
+ * and zero
+ */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ Set_invalidflag();
+ Sgl_makequietnan(resultp1);
+ Sgl_copytoptr(resultp1,dstptr);
+ return(NOEXCEPTION);
+ }
+ /*
+ * Check third operand for infinity with a
+ * sign opposite of the multiply result
+ */
+ if (Sgl_isinfinity(opnd3) &&
+ (Sgl_sign(resultp1) ^ Sgl_sign(opnd3))) {
+ /*
+ * invalid since attempting a magnitude
+ * subtraction of infinities
+ */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ Set_invalidflag();
+ Sgl_makequietnan(resultp1);
+ Sgl_copytoptr(resultp1,dstptr);
+ return(NOEXCEPTION);
+ }
+
+ /*
+ * return infinity
+ */
+ Sgl_setinfinity_exponentmantissa(resultp1);
+ Sgl_copytoptr(resultp1,dstptr);
+ return(NOEXCEPTION);
+ }
+ }
+ else {
+ /*
+ * is NaN; signaling or quiet?
+ */
+ if (Sgl_isone_signaling(opnd1)) {
+ /* trap if INVALIDTRAP enabled */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_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(OPC_2E_INVALIDEXCEPTION);
+ /* make NaN quiet */
+ Set_invalidflag();
+ Sgl_set_quiet(opnd2);
+ Sgl_copytoptr(opnd2,dstptr);
+ return(NOEXCEPTION);
+ }
+ /*
+ * is third operand a signaling NaN?
+ */
+ else if (Sgl_is_signalingnan(opnd3)) {
+ /* trap if INVALIDTRAP enabled */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ /* make NaN quiet */
+ Set_invalidflag();
+ Sgl_set_quiet(opnd3);
+ Sgl_copytoptr(opnd3,dstptr);
+ return(NOEXCEPTION);
+ }
+ /*
+ * return quiet NaN
+ */
+ Sgl_copytoptr(opnd1,dstptr);
+ return(NOEXCEPTION);
+ }
+ }
+
+ /*
+ * check second operand for NaN's or infinity
+ */
+ if (Sgl_isinfinity_exponent(opnd2)) {
+ if (Sgl_iszero_mantissa(opnd2)) {
+ if (Sgl_isnotnan(opnd3)) {
+ if (Sgl_iszero_exponentmantissa(opnd1)) {
+ /*
+ * invalid since multiply operands are
+ * zero & infinity
+ */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ Set_invalidflag();
+ Sgl_makequietnan(opnd2);
+ Sgl_copytoptr(opnd2,dstptr);
+ return(NOEXCEPTION);
+ }
+
+ /*
+ * Check third operand for infinity with a
+ * sign opposite of the multiply result
+ */
+ if (Sgl_isinfinity(opnd3) &&
+ (Sgl_sign(resultp1) ^ Sgl_sign(opnd3))) {
+ /*
+ * invalid since attempting a magnitude
+ * subtraction of infinities
+ */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ Set_invalidflag();
+ Sgl_makequietnan(resultp1);
+ Sgl_copytoptr(resultp1,dstptr);
+ return(NOEXCEPTION);
+ }
+
+ /*
+ * return infinity
+ */
+ Sgl_setinfinity_exponentmantissa(resultp1);
+ Sgl_copytoptr(resultp1,dstptr);
+ return(NOEXCEPTION);
+ }
+ }
+ else {
+ /*
+ * is NaN; signaling or quiet?
+ */
+ if (Sgl_isone_signaling(opnd2)) {
+ /* trap if INVALIDTRAP enabled */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ /* make NaN quiet */
+ Set_invalidflag();
+ Sgl_set_quiet(opnd2);
+ }
+ /*
+ * is third operand a signaling NaN?
+ */
+ else if (Sgl_is_signalingnan(opnd3)) {
+ /* trap if INVALIDTRAP enabled */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ /* make NaN quiet */
+ Set_invalidflag();
+ Sgl_set_quiet(opnd3);
+ Sgl_copytoptr(opnd3,dstptr);
+ return(NOEXCEPTION);
+ }
+ /*
+ * return quiet NaN
+ */
+ Sgl_copytoptr(opnd2,dstptr);
+ return(NOEXCEPTION);
+ }
+ }
+
+ /*
+ * check third operand for NaN's or infinity
+ */
+ if (Sgl_isinfinity_exponent(opnd3)) {
+ if (Sgl_iszero_mantissa(opnd3)) {
+ /* return infinity */
+ Sgl_copytoptr(opnd3,dstptr);
+ return(NOEXCEPTION);
+ } else {
+ /*
+ * is NaN; signaling or quiet?
+ */
+ if (Sgl_isone_signaling(opnd3)) {
+ /* trap if INVALIDTRAP enabled */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ /* make NaN quiet */
+ Set_invalidflag();
+ Sgl_set_quiet(opnd3);
+ }
+ /*
+ * return quiet NaN
+ */
+ Sgl_copytoptr(opnd3,dstptr);
+ return(NOEXCEPTION);
+ }
+ }
+
+ /*
+ * Generate multiply mantissa
+ */
+ if (Sgl_isnotzero_exponent(opnd1)) {
+ /* set hidden bit */
+ Sgl_clear_signexponent_set_hidden(opnd1);
+ }
+ else {
+ /* check for zero */
+ if (Sgl_iszero_mantissa(opnd1)) {
+ /*
+ * Perform the add opnd3 with zero here.
+ */
+ if (Sgl_iszero_exponentmantissa(opnd3)) {
+ if (Is_rounding_mode(ROUNDMINUS)) {
+ Sgl_or_signs(opnd3,resultp1);
+ } else {
+ Sgl_and_signs(opnd3,resultp1);
+ }
+ }
+ /*
+ * Now let's check for trapped underflow case.
+ */
+ else if (Sgl_iszero_exponent(opnd3) &&
+ Is_underflowtrap_enabled()) {
+ /* need to normalize results mantissa */
+ sign_save = Sgl_signextendedsign(opnd3);
+ result_exponent = 0;
+ Sgl_leftshiftby1(opnd3);
+ Sgl_normalize(opnd3,result_exponent);
+ Sgl_set_sign(opnd3,/*using*/sign_save);
+ Sgl_setwrapped_exponent(opnd3,result_exponent,
+ unfl);
+ Sgl_copytoptr(opnd3,dstptr);
+ /* inexact = FALSE */
+ return(OPC_2E_UNDERFLOWEXCEPTION);
+ }
+ Sgl_copytoptr(opnd3,dstptr);
+ return(NOEXCEPTION);
+ }
+ /* is denormalized, adjust exponent */
+ Sgl_clear_signexponent(opnd1);
+ Sgl_leftshiftby1(opnd1);
+ Sgl_normalize(opnd1,mpy_exponent);
+ }
+ /* opnd2 needs to have hidden bit set with msb in hidden bit */
+ if (Sgl_isnotzero_exponent(opnd2)) {
+ Sgl_clear_signexponent_set_hidden(opnd2);
+ }
+ else {
+ /* check for zero */
+ if (Sgl_iszero_mantissa(opnd2)) {
+ /*
+ * Perform the add opnd3 with zero here.
+ */
+ if (Sgl_iszero_exponentmantissa(opnd3)) {
+ if (Is_rounding_mode(ROUNDMINUS)) {
+ Sgl_or_signs(opnd3,resultp1);
+ } else {
+ Sgl_and_signs(opnd3,resultp1);
+ }
+ }
+ /*
+ * Now let's check for trapped underflow case.
+ */
+ else if (Sgl_iszero_exponent(opnd3) &&
+ Is_underflowtrap_enabled()) {
+ /* need to normalize results mantissa */
+ sign_save = Sgl_signextendedsign(opnd3);
+ result_exponent = 0;
+ Sgl_leftshiftby1(opnd3);
+ Sgl_normalize(opnd3,result_exponent);
+ Sgl_set_sign(opnd3,/*using*/sign_save);
+ Sgl_setwrapped_exponent(opnd3,result_exponent,
+ unfl);
+ Sgl_copytoptr(opnd3,dstptr);
+ /* inexact = FALSE */
+ return(OPC_2E_UNDERFLOWEXCEPTION);
+ }
+ Sgl_copytoptr(opnd3,dstptr);
+ return(NOEXCEPTION);
+ }
+ /* is denormalized; want to normalize */
+ Sgl_clear_signexponent(opnd2);
+ Sgl_leftshiftby1(opnd2);
+ Sgl_normalize(opnd2,mpy_exponent);
+ }
+
+ /* Multiply the first two source mantissas together */
+
+ /*
+ * The intermediate result will be kept in tmpres,
+ * which needs enough room for 106 bits of mantissa,
+ * so lets call it a Double extended.
+ */
+ Sglext_setzero(tmpresp1,tmpresp2);
+
+ /*
+ * Four bits at a time are inspected in each loop, and a
+ * simple shift and add multiply algorithm is used.
+ */
+ for (count = SGL_P-1; count >= 0; count -= 4) {
+ Sglext_rightshiftby4(tmpresp1,tmpresp2);
+ if (Sbit28(opnd1)) {
+ /* Twoword_add should be an ADD followed by 2 ADDC's */
+ Twoword_add(tmpresp1, tmpresp2, opnd2<<3, 0);
+ }
+ if (Sbit29(opnd1)) {
+ Twoword_add(tmpresp1, tmpresp2, opnd2<<2, 0);
+ }
+ if (Sbit30(opnd1)) {
+ Twoword_add(tmpresp1, tmpresp2, opnd2<<1, 0);
+ }
+ if (Sbit31(opnd1)) {
+ Twoword_add(tmpresp1, tmpresp2, opnd2, 0);
+ }
+ Sgl_rightshiftby4(opnd1);
+ }
+ if (Is_sexthiddenoverflow(tmpresp1)) {
+ /* result mantissa >= 2 (mantissa overflow) */
+ mpy_exponent++;
+ Sglext_rightshiftby4(tmpresp1,tmpresp2);
+ } else {
+ Sglext_rightshiftby3(tmpresp1,tmpresp2);
+ }
+
+ /*
+ * Restore the sign of the mpy result which was saved in resultp1.
+ * The exponent will continue to be kept in mpy_exponent.
+ */
+ Sglext_set_sign(tmpresp1,Sgl_sign(resultp1));
+
+ /*
+ * No rounding is required, since the result of the multiply
+ * is exact in the extended format.
+ */
+
+ /*
+ * Now we are ready to perform the add portion of the operation.
+ *
+ * The exponents need to be kept as integers for now, since the
+ * multiply result might not fit into the exponent field. We
+ * can't overflow or underflow because of this yet, since the
+ * add could bring the final result back into range.
+ */
+ add_exponent = Sgl_exponent(opnd3);
+
+ /*
+ * Check for denormalized or zero add operand.
+ */
+ if (add_exponent == 0) {
+ /* check for zero */
+ if (Sgl_iszero_mantissa(opnd3)) {
+ /* right is zero */
+ /* Left can't be zero and must be result.
+ *
+ * The final result is now in tmpres and mpy_exponent,
+ * and needs to be rounded and squeezed back into
+ * double precision format from double extended.
+ */
+ result_exponent = mpy_exponent;
+ Sglext_copy(tmpresp1,tmpresp2,resultp1,resultp2);
+ sign_save = Sgl_signextendedsign(resultp1);/*save sign*/
+ goto round;
+ }
+
+ /*
+ * Neither are zeroes.
+ * Adjust exponent and normalize add operand.
+ */
+ sign_save = Sgl_signextendedsign(opnd3); /* save sign */
+ Sgl_clear_signexponent(opnd3);
+ Sgl_leftshiftby1(opnd3);
+ Sgl_normalize(opnd3,add_exponent);
+ Sgl_set_sign(opnd3,sign_save); /* restore sign */
+ } else {
+ Sgl_clear_exponent_set_hidden(opnd3);
+ }
+ /*
+ * Copy opnd3 to the double extended variable called right.
+ */
+ Sgl_copyto_sglext(opnd3,rightp1,rightp2);
+
+ /*
+ * A zero "save" helps discover equal operands (for later),
+ * and is used in swapping operands (if needed).
+ */
+ Sglext_xortointp1(tmpresp1,rightp1,/*to*/save);
+
+ /*
+ * Compare magnitude of operands.
+ */
+ Sglext_copytoint_exponentmantissa(tmpresp1,signlessleft1);
+ Sglext_copytoint_exponentmantissa(rightp1,signlessright1);
+ if (mpy_exponent < add_exponent || mpy_exponent == add_exponent &&
+ Sglext_ismagnitudeless(signlessleft1,signlessright1)) {
+ /*
+ * Set the left operand to the larger one by XOR swap.
+ * First finish the first word "save".
+ */
+ Sglext_xorfromintp1(save,rightp1,/*to*/rightp1);
+ Sglext_xorfromintp1(save,tmpresp1,/*to*/tmpresp1);
+ Sglext_swap_lower(tmpresp2,rightp2);
+ /* also setup exponents used in rest of routine */
+ diff_exponent = add_exponent - mpy_exponent;
+ result_exponent = add_exponent;
+ } else {
+ /* also setup exponents used in rest of routine */
+ diff_exponent = mpy_exponent - add_exponent;
+ result_exponent = mpy_exponent;
+ }
+ /* Invariant: left is not smaller than right. */
+
+ /*
+ * Special case alignment of operands that would force alignment
+ * beyond the extent of the extension. A further optimization
+ * could special case this but only reduces the path length for
+ * this infrequent case.
+ */
+ if (diff_exponent > SGLEXT_THRESHOLD) {
+ diff_exponent = SGLEXT_THRESHOLD;
+ }
+
+ /* Align right operand by shifting it to the right */
+ Sglext_clear_sign(rightp1);
+ Sglext_right_align(rightp1,rightp2,/*shifted by*/diff_exponent);
+
+ /* Treat sum and difference of the operands separately. */
+ if ((int)save < 0) {
+ /*
+ * Difference of the two operands. Overflow can occur if the
+ * multiply overflowed. A borrow can occur out of the hidden
+ * bit and force a post normalization phase.
+ */
+ Sglext_subtract(tmpresp1,tmpresp2, rightp1,rightp2,
+ resultp1,resultp2);
+ sign_save = Sgl_signextendedsign(resultp1);
+ if (Sgl_iszero_hidden(resultp1)) {
+ /* Handle normalization */
+ /* A straightforward algorithm would now shift the
+ * result and extension left until the hidden bit
+ * becomes one. Not all of the extension bits need
+ * participate in the shift. Only the two most
+ * significant bits (round and guard) are needed.
+ * If only a single shift is needed then the guard
+ * bit becomes a significant low order bit and the
+ * extension must participate in the rounding.
+ * If more than a single shift is needed, then all
+ * bits to the right of the guard bit are zeros,
+ * and the guard bit may or may not be zero. */
+ Sglext_leftshiftby1(resultp1,resultp2);
+
+ /* Need to check for a zero result. The sign and
+ * exponent fields have already been zeroed. The more
+ * efficient test of the full object can be used.
+ */
+ if (Sglext_iszero(resultp1,resultp2)) {
+ /* Must have been "x-x" or "x+(-x)". */
+ if (Is_rounding_mode(ROUNDMINUS))
+ Sgl_setone_sign(resultp1);
+ Sgl_copytoptr(resultp1,dstptr);
+ return(NOEXCEPTION);
+ }
+ result_exponent--;
+
+ /* Look to see if normalization is finished. */
+ if (Sgl_isone_hidden(resultp1)) {
+ /* No further normalization is needed */
+ goto round;
+ }
+
+ /* Discover first one bit to determine shift amount.
+ * Use a modified binary search. We have already
+ * shifted the result one position right and still
+ * not found a one so the remainder of the extension
+ * must be zero and simplifies rounding. */
+ /* Scan bytes */
+ while (Sgl_iszero_hiddenhigh7mantissa(resultp1)) {
+ Sglext_leftshiftby8(resultp1,resultp2);
+ result_exponent -= 8;
+ }
+ /* Now narrow it down to the nibble */
+ if (Sgl_iszero_hiddenhigh3mantissa(resultp1)) {
+ /* The lower nibble contains the
+ * normalizing one */
+ Sglext_leftshiftby4(resultp1,resultp2);
+ result_exponent -= 4;
+ }
+ /* Select case where first bit is set (already
+ * normalized) otherwise select the proper shift. */
+ jumpsize = Sgl_hiddenhigh3mantissa(resultp1);
+ if (jumpsize <= 7) switch(jumpsize) {
+ case 1:
+ Sglext_leftshiftby3(resultp1,resultp2);
+ result_exponent -= 3;
+ break;
+ case 2:
+ case 3:
+ Sglext_leftshiftby2(resultp1,resultp2);
+ result_exponent -= 2;
+ break;
+ case 4:
+ case 5:
+ case 6:
+ case 7:
+ Sglext_leftshiftby1(resultp1,resultp2);
+ result_exponent -= 1;
+ break;
+ }
+ } /* end if (hidden...)... */
+ /* Fall through and round */
+ } /* end if (save < 0)... */
+ else {
+ /* Add magnitudes */
+ Sglext_addition(tmpresp1,tmpresp2,
+ rightp1,rightp2, /*to*/resultp1,resultp2);
+ sign_save = Sgl_signextendedsign(resultp1);
+ if (Sgl_isone_hiddenoverflow(resultp1)) {
+ /* Prenormalization required. */
+ Sglext_arithrightshiftby1(resultp1,resultp2);
+ result_exponent++;
+ } /* end if hiddenoverflow... */
+ } /* end else ...add magnitudes... */
+
+ /* Round the result. If the extension and lower two words are
+ * all zeros, then the result is exact. Otherwise round in the
+ * correct direction. Underflow is possible. If a postnormalization
+ * is necessary, then the mantissa is all zeros so no shift is needed.
+ */
+ round:
+ if (result_exponent <= 0 && !Is_underflowtrap_enabled()) {
+ Sglext_denormalize(resultp1,resultp2,result_exponent,is_tiny);
+ }
+ Sgl_set_sign(resultp1,/*using*/sign_save);
+ if (Sglext_isnotzero_mantissap2(resultp2)) {
+ inexact = TRUE;
+ switch(Rounding_mode()) {
+ case ROUNDNEAREST: /* The default. */
+ if (Sglext_isone_highp2(resultp2)) {
+ /* at least 1/2 ulp */
+ if (Sglext_isnotzero_low31p2(resultp2) ||
+ Sglext_isone_lowp1(resultp1)) {
+ /* either exactly half way and odd or
+ * more than 1/2ulp */
+ Sgl_increment(resultp1);
+ }
+ }
+ break;
+
+ case ROUNDPLUS:
+ if (Sgl_iszero_sign(resultp1)) {
+ /* Round up positive results */
+ Sgl_increment(resultp1);
+ }
+ break;
+
+ case ROUNDMINUS:
+ if (Sgl_isone_sign(resultp1)) {
+ /* Round down negative results */
+ Sgl_increment(resultp1);
+ }
+
+ case ROUNDZERO:;
+ /* truncate is simple */
+ } /* end switch... */
+ if (Sgl_isone_hiddenoverflow(resultp1)) result_exponent++;
+ }
+ if (result_exponent >= SGL_INFINITY_EXPONENT) {
+ /* Overflow */
+ if (Is_overflowtrap_enabled()) {
+ /*
+ * Adjust bias of result
+ */
+ Sgl_setwrapped_exponent(resultp1,result_exponent,ovfl);
+ Sgl_copytoptr(resultp1,dstptr);
+ if (inexact)
+ if (Is_inexacttrap_enabled())
+ return (OPC_2E_OVERFLOWEXCEPTION |
+ OPC_2E_INEXACTEXCEPTION);
+ else Set_inexactflag();
+ return (OPC_2E_OVERFLOWEXCEPTION);
+ }
+ inexact = TRUE;
+ Set_overflowflag();
+ Sgl_setoverflow(resultp1);
+ } else if (result_exponent <= 0) { /* underflow case */
+ if (Is_underflowtrap_enabled()) {
+ /*
+ * Adjust bias of result
+ */
+ Sgl_setwrapped_exponent(resultp1,result_exponent,unfl);
+ Sgl_copytoptr(resultp1,dstptr);
+ if (inexact)
+ if (Is_inexacttrap_enabled())
+ return (OPC_2E_UNDERFLOWEXCEPTION |
+ OPC_2E_INEXACTEXCEPTION);
+ else Set_inexactflag();
+ return(OPC_2E_UNDERFLOWEXCEPTION);
+ }
+ else if (inexact && is_tiny) Set_underflowflag();
+ }
+ else Sgl_set_exponent(resultp1,result_exponent);
+ Sgl_copytoptr(resultp1,dstptr);
+ if (inexact)
+ if (Is_inexacttrap_enabled()) return(OPC_2E_INEXACTEXCEPTION);
+ else Set_inexactflag();
+ return(NOEXCEPTION);
+}
+
+/*
+ * Single Floating-point Multiply Negate Fused Add
+ */
+
+sgl_fmpynfadd(src1ptr,src2ptr,src3ptr,status,dstptr)
+
+sgl_floating_point *src1ptr, *src2ptr, *src3ptr, *dstptr;
+unsigned int *status;
+{
+ unsigned int opnd1, opnd2, opnd3;
+ register unsigned int tmpresp1, tmpresp2;
+ unsigned int rightp1, rightp2;
+ unsigned int resultp1, resultp2 = 0;
+ register int mpy_exponent, add_exponent, count;
+ boolean inexact = FALSE, is_tiny = FALSE;
+
+ unsigned int signlessleft1, signlessright1, save;
+ register int result_exponent, diff_exponent;
+ int sign_save, jumpsize;
+
+ Sgl_copyfromptr(src1ptr,opnd1);
+ Sgl_copyfromptr(src2ptr,opnd2);
+ Sgl_copyfromptr(src3ptr,opnd3);
+
+ /*
+ * set sign bit of result of multiply
+ */
+ if (Sgl_sign(opnd1) ^ Sgl_sign(opnd2))
+ Sgl_setzero(resultp1);
+ else
+ Sgl_setnegativezero(resultp1);
+
+ /*
+ * Generate multiply exponent
+ */
+ mpy_exponent = Sgl_exponent(opnd1) + Sgl_exponent(opnd2) - SGL_BIAS;
+
+ /*
+ * check first operand for NaN's or infinity
+ */
+ if (Sgl_isinfinity_exponent(opnd1)) {
+ if (Sgl_iszero_mantissa(opnd1)) {
+ if (Sgl_isnotnan(opnd2) && Sgl_isnotnan(opnd3)) {
+ if (Sgl_iszero_exponentmantissa(opnd2)) {
+ /*
+ * invalid since operands are infinity
+ * and zero
+ */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ Set_invalidflag();
+ Sgl_makequietnan(resultp1);
+ Sgl_copytoptr(resultp1,dstptr);
+ return(NOEXCEPTION);
+ }
+ /*
+ * Check third operand for infinity with a
+ * sign opposite of the multiply result
+ */
+ if (Sgl_isinfinity(opnd3) &&
+ (Sgl_sign(resultp1) ^ Sgl_sign(opnd3))) {
+ /*
+ * invalid since attempting a magnitude
+ * subtraction of infinities
+ */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ Set_invalidflag();
+ Sgl_makequietnan(resultp1);
+ Sgl_copytoptr(resultp1,dstptr);
+ return(NOEXCEPTION);
+ }
+
+ /*
+ * return infinity
+ */
+ Sgl_setinfinity_exponentmantissa(resultp1);
+ Sgl_copytoptr(resultp1,dstptr);
+ return(NOEXCEPTION);
+ }
+ }
+ else {
+ /*
+ * is NaN; signaling or quiet?
+ */
+ if (Sgl_isone_signaling(opnd1)) {
+ /* trap if INVALIDTRAP enabled */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_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(OPC_2E_INVALIDEXCEPTION);
+ /* make NaN quiet */
+ Set_invalidflag();
+ Sgl_set_quiet(opnd2);
+ Sgl_copytoptr(opnd2,dstptr);
+ return(NOEXCEPTION);
+ }
+ /*
+ * is third operand a signaling NaN?
+ */
+ else if (Sgl_is_signalingnan(opnd3)) {
+ /* trap if INVALIDTRAP enabled */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ /* make NaN quiet */
+ Set_invalidflag();
+ Sgl_set_quiet(opnd3);
+ Sgl_copytoptr(opnd3,dstptr);
+ return(NOEXCEPTION);
+ }
+ /*
+ * return quiet NaN
+ */
+ Sgl_copytoptr(opnd1,dstptr);
+ return(NOEXCEPTION);
+ }
+ }
+
+ /*
+ * check second operand for NaN's or infinity
+ */
+ if (Sgl_isinfinity_exponent(opnd2)) {
+ if (Sgl_iszero_mantissa(opnd2)) {
+ if (Sgl_isnotnan(opnd3)) {
+ if (Sgl_iszero_exponentmantissa(opnd1)) {
+ /*
+ * invalid since multiply operands are
+ * zero & infinity
+ */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ Set_invalidflag();
+ Sgl_makequietnan(opnd2);
+ Sgl_copytoptr(opnd2,dstptr);
+ return(NOEXCEPTION);
+ }
+
+ /*
+ * Check third operand for infinity with a
+ * sign opposite of the multiply result
+ */
+ if (Sgl_isinfinity(opnd3) &&
+ (Sgl_sign(resultp1) ^ Sgl_sign(opnd3))) {
+ /*
+ * invalid since attempting a magnitude
+ * subtraction of infinities
+ */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ Set_invalidflag();
+ Sgl_makequietnan(resultp1);
+ Sgl_copytoptr(resultp1,dstptr);
+ return(NOEXCEPTION);
+ }
+
+ /*
+ * return infinity
+ */
+ Sgl_setinfinity_exponentmantissa(resultp1);
+ Sgl_copytoptr(resultp1,dstptr);
+ return(NOEXCEPTION);
+ }
+ }
+ else {
+ /*
+ * is NaN; signaling or quiet?
+ */
+ if (Sgl_isone_signaling(opnd2)) {
+ /* trap if INVALIDTRAP enabled */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ /* make NaN quiet */
+ Set_invalidflag();
+ Sgl_set_quiet(opnd2);
+ }
+ /*
+ * is third operand a signaling NaN?
+ */
+ else if (Sgl_is_signalingnan(opnd3)) {
+ /* trap if INVALIDTRAP enabled */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ /* make NaN quiet */
+ Set_invalidflag();
+ Sgl_set_quiet(opnd3);
+ Sgl_copytoptr(opnd3,dstptr);
+ return(NOEXCEPTION);
+ }
+ /*
+ * return quiet NaN
+ */
+ Sgl_copytoptr(opnd2,dstptr);
+ return(NOEXCEPTION);
+ }
+ }
+
+ /*
+ * check third operand for NaN's or infinity
+ */
+ if (Sgl_isinfinity_exponent(opnd3)) {
+ if (Sgl_iszero_mantissa(opnd3)) {
+ /* return infinity */
+ Sgl_copytoptr(opnd3,dstptr);
+ return(NOEXCEPTION);
+ } else {
+ /*
+ * is NaN; signaling or quiet?
+ */
+ if (Sgl_isone_signaling(opnd3)) {
+ /* trap if INVALIDTRAP enabled */
+ if (Is_invalidtrap_enabled())
+ return(OPC_2E_INVALIDEXCEPTION);
+ /* make NaN quiet */
+ Set_invalidflag();
+ Sgl_set_quiet(opnd3);
+ }
+ /*
+ * return quiet NaN
+ */
+ Sgl_copytoptr(opnd3,dstptr);
+ return(NOEXCEPTION);
+ }
+ }
+
+ /*
+ * Generate multiply mantissa
+ */
+ if (Sgl_isnotzero_exponent(opnd1)) {
+ /* set hidden bit */
+ Sgl_clear_signexponent_set_hidden(opnd1);
+ }
+ else {
+ /* check for zero */
+ if (Sgl_iszero_mantissa(opnd1)) {
+ /*
+ * Perform the add opnd3 with zero here.
+ */
+ if (Sgl_iszero_exponentmantissa(opnd3)) {
+ if (Is_rounding_mode(ROUNDMINUS)) {
+ Sgl_or_signs(opnd3,resultp1);
+ } else {
+ Sgl_and_signs(opnd3,resultp1);
+ }
+ }
+ /*
+ * Now let's check for trapped underflow case.
+ */
+ else if (Sgl_iszero_exponent(opnd3) &&
+ Is_underflowtrap_enabled()) {
+ /* need to normalize results mantissa */
+ sign_save = Sgl_signextendedsign(opnd3);
+ result_exponent = 0;
+ Sgl_leftshiftby1(opnd3);
+ Sgl_normalize(opnd3,result_exponent);
+ Sgl_set_sign(opnd3,/*using*/sign_save);
+ Sgl_setwrapped_exponent(opnd3,result_exponent,
+ unfl);
+ Sgl_copytoptr(opnd3,dstptr);
+ /* inexact = FALSE */
+ return(OPC_2E_UNDERFLOWEXCEPTION);
+ }
+ Sgl_copytoptr(opnd3,dstptr);
+ return(NOEXCEPTION);
+ }
+ /* is denormalized, adjust exponent */
+ Sgl_clear_signexponent(opnd1);
+ Sgl_leftshiftby1(opnd1);
+ Sgl_normalize(opnd1,mpy_exponent);
+ }
+ /* opnd2 needs to have hidden bit set with msb in hidden bit */
+ if (Sgl_isnotzero_exponent(opnd2)) {
+ Sgl_clear_signexponent_set_hidden(opnd2);
+ }
+ else {
+ /* check for zero */
+ if (Sgl_iszero_mantissa(opnd2)) {
+ /*
+ * Perform the add opnd3 with zero here.
+ */
+ if (Sgl_iszero_exponentmantissa(opnd3)) {
+ if (Is_rounding_mode(ROUNDMINUS)) {
+ Sgl_or_signs(opnd3,resultp1);
+ } else {
+ Sgl_and_signs(opnd3,resultp1);
+ }
+ }
+ /*
+ * Now let's check for trapped underflow case.
+ */
+ else if (Sgl_iszero_exponent(opnd3) &&
+ Is_underflowtrap_enabled()) {
+ /* need to normalize results mantissa */
+ sign_save = Sgl_signextendedsign(opnd3);
+ result_exponent = 0;
+ Sgl_leftshiftby1(opnd3);
+ Sgl_normalize(opnd3,result_exponent);
+ Sgl_set_sign(opnd3,/*using*/sign_save);
+ Sgl_setwrapped_exponent(opnd3,result_exponent,
+ unfl);
+ Sgl_copytoptr(opnd3,dstptr);
+ /* inexact = FALSE */
+ return(OPC_2E_UNDERFLOWEXCEPTION);
+ }
+ Sgl_copytoptr(opnd3,dstptr);
+ return(NOEXCEPTION);
+ }
+ /* is denormalized; want to normalize */
+ Sgl_clear_signexponent(opnd2);
+ Sgl_leftshiftby1(opnd2);
+ Sgl_normalize(opnd2,mpy_exponent);
+ }
+
+ /* Multiply the first two source mantissas together */
+
+ /*
+ * The intermediate result will be kept in tmpres,
+ * which needs enough room for 106 bits of mantissa,
+ * so lets call it a Double extended.
+ */
+ Sglext_setzero(tmpresp1,tmpresp2);
+
+ /*
+ * Four bits at a time are inspected in each loop, and a
+ * simple shift and add multiply algorithm is used.
+ */
+ for (count = SGL_P-1; count >= 0; count -= 4) {
+ Sglext_rightshiftby4(tmpresp1,tmpresp2);
+ if (Sbit28(opnd1)) {
+ /* Twoword_add should be an ADD followed by 2 ADDC's */
+ Twoword_add(tmpresp1, tmpresp2, opnd2<<3, 0);
+ }
+ if (Sbit29(opnd1)) {
+ Twoword_add(tmpresp1, tmpresp2, opnd2<<2, 0);
+ }
+ if (Sbit30(opnd1)) {
+ Twoword_add(tmpresp1, tmpresp2, opnd2<<1, 0);
+ }
+ if (Sbit31(opnd1)) {
+ Twoword_add(tmpresp1, tmpresp2, opnd2, 0);
+ }
+ Sgl_rightshiftby4(opnd1);
+ }
+ if (Is_sexthiddenoverflow(tmpresp1)) {
+ /* result mantissa >= 2 (mantissa overflow) */
+ mpy_exponent++;
+ Sglext_rightshiftby4(tmpresp1,tmpresp2);
+ } else {
+ Sglext_rightshiftby3(tmpresp1,tmpresp2);
+ }
+
+ /*
+ * Restore the sign of the mpy result which was saved in resultp1.
+ * The exponent will continue to be kept in mpy_exponent.
+ */
+ Sglext_set_sign(tmpresp1,Sgl_sign(resultp1));
+
+ /*
+ * No rounding is required, since the result of the multiply
+ * is exact in the extended format.
+ */
+
+ /*
+ * Now we are ready to perform the add portion of the operation.
+ *
+ * The exponents need to be kept as integers for now, since the
+ * multiply result might not fit into the exponent field. We
+ * can't overflow or underflow because of this yet, since the
+ * add could bring the final result back into range.
+ */
+ add_exponent = Sgl_exponent(opnd3);
+
+ /*
+ * Check for denormalized or zero add operand.
+ */
+ if (add_exponent == 0) {
+ /* check for zero */
+ if (Sgl_iszero_mantissa(opnd3)) {
+ /* right is zero */
+ /* Left can't be zero and must be result.
+ *
+ * The final result is now in tmpres and mpy_exponent,
+ * and needs to be rounded and squeezed back into
+ * double precision format from double extended.
+ */
+ result_exponent = mpy_exponent;
+ Sglext_copy(tmpresp1,tmpresp2,resultp1,resultp2);
+ sign_save = Sgl_signextendedsign(resultp1);/*save sign*/
+ goto round;
+ }
+
+ /*
+ * Neither are zeroes.
+ * Adjust exponent and normalize add operand.
+ */
+ sign_save = Sgl_signextendedsign(opnd3); /* save sign */
+ Sgl_clear_signexponent(opnd3);
+ Sgl_leftshiftby1(opnd3);
+ Sgl_normalize(opnd3,add_exponent);
+ Sgl_set_sign(opnd3,sign_save); /* restore sign */
+ } else {
+ Sgl_clear_exponent_set_hidden(opnd3);
+ }
+ /*
+ * Copy opnd3 to the double extended variable called right.
+ */
+ Sgl_copyto_sglext(opnd3,rightp1,rightp2);
+
+ /*
+ * A zero "save" helps discover equal operands (for later),
+ * and is used in swapping operands (if needed).
+ */
+ Sglext_xortointp1(tmpresp1,rightp1,/*to*/save);
+
+ /*
+ * Compare magnitude of operands.
+ */
+ Sglext_copytoint_exponentmantissa(tmpresp1,signlessleft1);
+ Sglext_copytoint_exponentmantissa(rightp1,signlessright1);
+ if (mpy_exponent < add_exponent || mpy_exponent == add_exponent &&
+ Sglext_ismagnitudeless(signlessleft1,signlessright1)) {
+ /*
+ * Set the left operand to the larger one by XOR swap.
+ * First finish the first word "save".
+ */
+ Sglext_xorfromintp1(save,rightp1,/*to*/rightp1);
+ Sglext_xorfromintp1(save,tmpresp1,/*to*/tmpresp1);
+ Sglext_swap_lower(tmpresp2,rightp2);
+ /* also setup exponents used in rest of routine */
+ diff_exponent = add_exponent - mpy_exponent;
+ result_exponent = add_exponent;
+ } else {
+ /* also setup exponents used in rest of routine */
+ diff_exponent = mpy_exponent - add_exponent;
+ result_exponent = mpy_exponent;
+ }
+ /* Invariant: left is not smaller than right. */
+
+ /*
+ * Special case alignment of operands that would force alignment
+ * beyond the extent of the extension. A further optimization
+ * could special case this but only reduces the path length for
+ * this infrequent case.
+ */
+ if (diff_exponent > SGLEXT_THRESHOLD) {
+ diff_exponent = SGLEXT_THRESHOLD;
+ }
+
+ /* Align right operand by shifting it to the right */
+ Sglext_clear_sign(rightp1);
+ Sglext_right_align(rightp1,rightp2,/*shifted by*/diff_exponent);
+
+ /* Treat sum and difference of the operands separately. */
+ if ((int)save < 0) {
+ /*
+ * Difference of the two operands. Overflow can occur if the
+ * multiply overflowed. A borrow can occur out of the hidden
+ * bit and force a post normalization phase.
+ */
+ Sglext_subtract(tmpresp1,tmpresp2, rightp1,rightp2,
+ resultp1,resultp2);
+ sign_save = Sgl_signextendedsign(resultp1);
+ if (Sgl_iszero_hidden(resultp1)) {
+ /* Handle normalization */
+ /* A straightforward algorithm would now shift the
+ * result and extension left until the hidden bit
+ * becomes one. Not all of the extension bits need
+ * participate in the shift. Only the two most
+ * significant bits (round and guard) are needed.
+ * If only a single shift is needed then the guard
+ * bit becomes a significant low order bit and the
+ * extension must participate in the rounding.
+ * If more than a single shift is needed, then all
+ * bits to the right of the guard bit are zeros,
+ * and the guard bit may or may not be zero. */
+ Sglext_leftshiftby1(resultp1,resultp2);
+
+ /* Need to check for a zero result. The sign and
+ * exponent fields have already been zeroed. The more
+ * efficient test of the full object can be used.
+ */
+ if (Sglext_iszero(resultp1,resultp2)) {
+ /* Must have been "x-x" or "x+(-x)". */
+ if (Is_rounding_mode(ROUNDMINUS))
+ Sgl_setone_sign(resultp1);
+ Sgl_copytoptr(resultp1,dstptr);
+ return(NOEXCEPTION);
+ }
+ result_exponent--;
+
+ /* Look to see if normalization is finished. */
+ if (Sgl_isone_hidden(resultp1)) {
+ /* No further normalization is needed */
+ goto round;
+ }
+
+ /* Discover first one bit to determine shift amount.
+ * Use a modified binary search. We have already
+ * shifted the result one position right and still
+ * not found a one so the remainder of the extension
+ * must be zero and simplifies rounding. */
+ /* Scan bytes */
+ while (Sgl_iszero_hiddenhigh7mantissa(resultp1)) {
+ Sglext_leftshiftby8(resultp1,resultp2);
+ result_exponent -= 8;
+ }
+ /* Now narrow it down to the nibble */
+ if (Sgl_iszero_hiddenhigh3mantissa(resultp1)) {
+ /* The lower nibble contains the
+ * normalizing one */
+ Sglext_leftshiftby4(resultp1,resultp2);
+ result_exponent -= 4;
+ }
+ /* Select case where first bit is set (already
+ * normalized) otherwise select the proper shift. */
+ jumpsize = Sgl_hiddenhigh3mantissa(resultp1);
+ if (jumpsize <= 7) switch(jumpsize) {
+ case 1:
+ Sglext_leftshiftby3(resultp1,resultp2);
+ result_exponent -= 3;
+ break;
+ case 2:
+ case 3:
+ Sglext_leftshiftby2(resultp1,resultp2);
+ result_exponent -= 2;
+ break;
+ case 4:
+ case 5:
+ case 6:
+ case 7:
+ Sglext_leftshiftby1(resultp1,resultp2);
+ result_exponent -= 1;
+ break;
+ }
+ } /* end if (hidden...)... */
+ /* Fall through and round */
+ } /* end if (save < 0)... */
+ else {
+ /* Add magnitudes */
+ Sglext_addition(tmpresp1,tmpresp2,
+ rightp1,rightp2, /*to*/resultp1,resultp2);
+ sign_save = Sgl_signextendedsign(resultp1);
+ if (Sgl_isone_hiddenoverflow(resultp1)) {
+ /* Prenormalization required. */
+ Sglext_arithrightshiftby1(resultp1,resultp2);
+ result_exponent++;
+ } /* end if hiddenoverflow... */
+ } /* end else ...add magnitudes... */
+
+ /* Round the result. If the extension and lower two words are
+ * all zeros, then the result is exact. Otherwise round in the
+ * correct direction. Underflow is possible. If a postnormalization
+ * is necessary, then the mantissa is all zeros so no shift is needed.
+ */
+ round:
+ if (result_exponent <= 0 && !Is_underflowtrap_enabled()) {
+ Sglext_denormalize(resultp1,resultp2,result_exponent,is_tiny);
+ }
+ Sgl_set_sign(resultp1,/*using*/sign_save);
+ if (Sglext_isnotzero_mantissap2(resultp2)) {
+ inexact = TRUE;
+ switch(Rounding_mode()) {
+ case ROUNDNEAREST: /* The default. */
+ if (Sglext_isone_highp2(resultp2)) {
+ /* at least 1/2 ulp */
+ if (Sglext_isnotzero_low31p2(resultp2) ||
+ Sglext_isone_lowp1(resultp1)) {
+ /* either exactly half way and odd or
+ * more than 1/2ulp */
+ Sgl_increment(resultp1);
+ }
+ }
+ break;
+
+ case ROUNDPLUS:
+ if (Sgl_iszero_sign(resultp1)) {
+ /* Round up positive results */
+ Sgl_increment(resultp1);
+ }
+ break;
+
+ case ROUNDMINUS:
+ if (Sgl_isone_sign(resultp1)) {
+ /* Round down negative results */
+ Sgl_increment(resultp1);
+ }
+
+ case ROUNDZERO:;
+ /* truncate is simple */
+ } /* end switch... */
+ if (Sgl_isone_hiddenoverflow(resultp1)) result_exponent++;
+ }
+ if (result_exponent >= SGL_INFINITY_EXPONENT) {
+ /* Overflow */
+ if (Is_overflowtrap_enabled()) {
+ /*
+ * Adjust bias of result
+ */
+ Sgl_setwrapped_exponent(resultp1,result_exponent,ovfl);
+ Sgl_copytoptr(resultp1,dstptr);
+ if (inexact)
+ if (Is_inexacttrap_enabled())
+ return (OPC_2E_OVERFLOWEXCEPTION |
+ OPC_2E_INEXACTEXCEPTION);
+ else Set_inexactflag();
+ return (OPC_2E_OVERFLOWEXCEPTION);
+ }
+ inexact = TRUE;
+ Set_overflowflag();
+ Sgl_setoverflow(resultp1);
+ } else if (result_exponent <= 0) { /* underflow case */
+ if (Is_underflowtrap_enabled()) {
+ /*
+ * Adjust bias of result
+ */
+ Sgl_setwrapped_exponent(resultp1,result_exponent,unfl);
+ Sgl_copytoptr(resultp1,dstptr);
+ if (inexact)
+ if (Is_inexacttrap_enabled())
+ return (OPC_2E_UNDERFLOWEXCEPTION |
+ OPC_2E_INEXACTEXCEPTION);
+ else Set_inexactflag();
+ return(OPC_2E_UNDERFLOWEXCEPTION);
+ }
+ else if (inexact && is_tiny) Set_underflowflag();
+ }
+ else Sgl_set_exponent(resultp1,result_exponent);
+ Sgl_copytoptr(resultp1,dstptr);
+ if (inexact)
+ if (Is_inexacttrap_enabled()) return(OPC_2E_INEXACTEXCEPTION);
+ else Set_inexactflag();
+ return(NOEXCEPTION);
+}
+