290 lines
7.4 KiB
C
290 lines
7.4 KiB
C
/*
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NetWinder Floating Point Emulator
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(c) Rebel.COM, 1998,1999
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(c) Philip Blundell, 1999
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Direct questions, comments to Scott Bambrough <scottb@netwinder.org>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include "fpa11.h"
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#include "milieu.h"
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#include "softfloat.h"
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#include "fpopcode.h"
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#include "fpa11.inl"
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#include "fpmodule.h"
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#include "fpmodule.inl"
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extern flag floatx80_is_nan(floatx80);
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extern flag float64_is_nan( float64);
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extern flag float32_is_nan( float32);
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void SetRoundingMode(const unsigned int opcode);
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unsigned int PerformFLT(const unsigned int opcode);
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unsigned int PerformFIX(const unsigned int opcode);
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static unsigned int
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PerformComparison(const unsigned int opcode);
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unsigned int EmulateCPRT(const unsigned int opcode)
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{
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unsigned int nRc = 1;
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//printk("EmulateCPRT(0x%08x)\n",opcode);
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if (opcode & 0x800000)
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{
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/* This is some variant of a comparison (PerformComparison will
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sort out which one). Since most of the other CPRT
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instructions are oddball cases of some sort or other it makes
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sense to pull this out into a fast path. */
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return PerformComparison(opcode);
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}
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/* Hint to GCC that we'd like a jump table rather than a load of CMPs */
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switch ((opcode & 0x700000) >> 20)
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{
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case FLT_CODE >> 20: nRc = PerformFLT(opcode); break;
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case FIX_CODE >> 20: nRc = PerformFIX(opcode); break;
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case WFS_CODE >> 20: writeFPSR(readRegister(getRd(opcode))); break;
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case RFS_CODE >> 20: writeRegister(getRd(opcode),readFPSR()); break;
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#if 0 /* We currently have no use for the FPCR, so there's no point
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in emulating it. */
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case WFC_CODE >> 20: writeFPCR(readRegister(getRd(opcode)));
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case RFC_CODE >> 20: writeRegister(getRd(opcode),readFPCR()); break;
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#endif
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default: nRc = 0;
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}
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return nRc;
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}
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unsigned int PerformFLT(const unsigned int opcode)
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{
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FPA11 *fpa11 = GET_FPA11();
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unsigned int nRc = 1;
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SetRoundingMode(opcode);
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switch (opcode & MASK_ROUNDING_PRECISION)
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{
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case ROUND_SINGLE:
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{
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fpa11->fType[getFn(opcode)] = typeSingle;
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fpa11->fpreg[getFn(opcode)].fSingle =
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int32_to_float32(readRegister(getRd(opcode)));
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}
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break;
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case ROUND_DOUBLE:
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{
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fpa11->fType[getFn(opcode)] = typeDouble;
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fpa11->fpreg[getFn(opcode)].fDouble =
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int32_to_float64(readRegister(getRd(opcode)));
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}
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break;
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case ROUND_EXTENDED:
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{
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fpa11->fType[getFn(opcode)] = typeExtended;
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fpa11->fpreg[getFn(opcode)].fExtended =
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int32_to_floatx80(readRegister(getRd(opcode)));
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}
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break;
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default: nRc = 0;
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}
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return nRc;
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}
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unsigned int PerformFIX(const unsigned int opcode)
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{
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FPA11 *fpa11 = GET_FPA11();
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unsigned int nRc = 1;
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unsigned int Fn = getFm(opcode);
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SetRoundingMode(opcode);
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switch (fpa11->fType[Fn])
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{
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case typeSingle:
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{
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writeRegister(getRd(opcode),
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float32_to_int32(fpa11->fpreg[Fn].fSingle));
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}
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break;
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case typeDouble:
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{
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writeRegister(getRd(opcode),
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float64_to_int32(fpa11->fpreg[Fn].fDouble));
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}
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break;
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case typeExtended:
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{
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writeRegister(getRd(opcode),
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floatx80_to_int32(fpa11->fpreg[Fn].fExtended));
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}
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break;
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default: nRc = 0;
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}
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return nRc;
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}
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static unsigned int __inline__
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PerformComparisonOperation(floatx80 Fn, floatx80 Fm)
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{
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unsigned int flags = 0;
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/* test for less than condition */
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if (floatx80_lt(Fn,Fm))
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{
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flags |= CC_NEGATIVE;
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}
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/* test for equal condition */
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if (floatx80_eq(Fn,Fm))
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{
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flags |= CC_ZERO;
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}
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/* test for greater than or equal condition */
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if (floatx80_lt(Fm,Fn))
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{
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flags |= CC_CARRY;
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}
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writeConditionCodes(flags);
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return 1;
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}
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/* This instruction sets the flags N, Z, C, V in the FPSR. */
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static unsigned int PerformComparison(const unsigned int opcode)
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{
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FPA11 *fpa11 = GET_FPA11();
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unsigned int Fn, Fm;
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floatx80 rFn, rFm;
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int e_flag = opcode & 0x400000; /* 1 if CxFE */
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int n_flag = opcode & 0x200000; /* 1 if CNxx */
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unsigned int flags = 0;
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//printk("PerformComparison(0x%08x)\n",opcode);
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Fn = getFn(opcode);
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Fm = getFm(opcode);
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/* Check for unordered condition and convert all operands to 80-bit
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format.
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?? Might be some mileage in avoiding this conversion if possible.
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Eg, if both operands are 32-bit, detect this and do a 32-bit
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comparison (cheaper than an 80-bit one). */
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switch (fpa11->fType[Fn])
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{
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case typeSingle:
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//printk("single.\n");
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if (float32_is_nan(fpa11->fpreg[Fn].fSingle))
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goto unordered;
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rFn = float32_to_floatx80(fpa11->fpreg[Fn].fSingle);
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break;
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case typeDouble:
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//printk("double.\n");
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if (float64_is_nan(fpa11->fpreg[Fn].fDouble))
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goto unordered;
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rFn = float64_to_floatx80(fpa11->fpreg[Fn].fDouble);
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break;
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case typeExtended:
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//printk("extended.\n");
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if (floatx80_is_nan(fpa11->fpreg[Fn].fExtended))
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goto unordered;
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rFn = fpa11->fpreg[Fn].fExtended;
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break;
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default: return 0;
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}
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if (CONSTANT_FM(opcode))
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{
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//printk("Fm is a constant: #%d.\n",Fm);
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rFm = getExtendedConstant(Fm);
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if (floatx80_is_nan(rFm))
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goto unordered;
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}
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else
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{
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//printk("Fm = r%d which contains a ",Fm);
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switch (fpa11->fType[Fm])
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{
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case typeSingle:
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//printk("single.\n");
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if (float32_is_nan(fpa11->fpreg[Fm].fSingle))
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goto unordered;
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rFm = float32_to_floatx80(fpa11->fpreg[Fm].fSingle);
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break;
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case typeDouble:
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//printk("double.\n");
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if (float64_is_nan(fpa11->fpreg[Fm].fDouble))
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goto unordered;
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rFm = float64_to_floatx80(fpa11->fpreg[Fm].fDouble);
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break;
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case typeExtended:
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//printk("extended.\n");
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if (floatx80_is_nan(fpa11->fpreg[Fm].fExtended))
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goto unordered;
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rFm = fpa11->fpreg[Fm].fExtended;
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break;
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default: return 0;
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}
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}
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if (n_flag)
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{
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rFm.high ^= 0x8000;
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}
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return PerformComparisonOperation(rFn,rFm);
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unordered:
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/* ?? The FPA data sheet is pretty vague about this, in particular
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about whether the non-E comparisons can ever raise exceptions.
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This implementation is based on a combination of what it says in
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the data sheet, observation of how the Acorn emulator actually
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behaves (and how programs expect it to) and guesswork. */
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flags |= CC_OVERFLOW;
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flags &= ~(CC_ZERO | CC_NEGATIVE);
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if (BIT_AC & readFPSR()) flags |= CC_CARRY;
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if (e_flag) float_raise(float_flag_invalid);
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writeConditionCodes(flags);
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return 1;
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}
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