362 lines
8.4 KiB
C
362 lines
8.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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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, 2001
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Direct questions, comments to Scott Bambrough <scottb@netwinder.org>
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*/
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#include "fpa11.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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#include "softfloat.h"
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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 PerformComparison(const unsigned int opcode);
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unsigned int EmulateCPRT(const unsigned int opcode)
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{
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if (opcode & 0x800000) {
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/* This is some variant of a comparison (PerformComparison
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will sort out which one). Since most of the other CPRT
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instructions are oddball cases of some sort or other it
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makes 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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case FLT_CODE >> 20:
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return PerformFLT(opcode);
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break;
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case FIX_CODE >> 20:
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return PerformFIX(opcode);
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break;
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case WFS_CODE >> 20:
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writeFPSR(readRegister(getRd(opcode)));
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break;
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case RFS_CODE >> 20:
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writeRegister(getRd(opcode), readFPSR());
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break;
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default:
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return 0;
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}
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return 1;
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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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struct roundingData roundData;
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roundData.mode = SetRoundingMode(opcode);
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roundData.precision = SetRoundingPrecision(opcode);
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roundData.exception = 0;
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switch (opcode & MASK_ROUNDING_PRECISION) {
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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 = int32_to_float32(&roundData, 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 = int32_to_float64(readRegister(getRd(opcode)));
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}
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break;
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#ifdef CONFIG_FPE_NWFPE_XP
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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 = int32_to_floatx80(readRegister(getRd(opcode)));
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}
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break;
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#endif
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default:
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return 0;
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}
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if (roundData.exception)
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float_raise(roundData.exception);
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return 1;
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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 Fn = getFm(opcode);
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struct roundingData roundData;
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roundData.mode = SetRoundingMode(opcode);
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roundData.precision = SetRoundingPrecision(opcode);
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roundData.exception = 0;
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switch (fpa11->fType[Fn]) {
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case typeSingle:
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{
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writeRegister(getRd(opcode), float32_to_int32(&roundData, 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), float64_to_int32(&roundData, fpa11->fpreg[Fn].fDouble));
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}
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break;
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#ifdef CONFIG_FPE_NWFPE_XP
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case typeExtended:
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{
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writeRegister(getRd(opcode), floatx80_to_int32(&roundData, fpa11->fpreg[Fn].fExtended));
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}
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break;
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#endif
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default:
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return 0;
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}
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if (roundData.exception)
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float_raise(roundData.exception);
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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 = getFn(opcode), Fm = getFm(opcode);
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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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#ifdef CONFIG_FPE_NWFPE_XP
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floatx80 rFn, rFm;
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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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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:
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return 0;
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}
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if (CONSTANT_FM(opcode)) {
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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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} else {
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//printk("Fm = r%d which contains a ",Fm);
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switch (fpa11->fType[Fm]) {
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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:
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return 0;
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}
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}
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if (n_flag)
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rFm.high ^= 0x8000;
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/* test for less than condition */
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if (floatx80_lt(rFn, rFm))
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flags |= CC_NEGATIVE;
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/* test for equal condition */
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if (floatx80_eq(rFn, rFm))
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flags |= CC_ZERO;
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/* test for greater than or equal condition */
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if (floatx80_lt(rFm, rFn))
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flags |= CC_CARRY;
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#else
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if (CONSTANT_FM(opcode)) {
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/* Fm is a constant. Do the comparison in whatever precision
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Fn happens to be stored in. */
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if (fpa11->fType[Fn] == typeSingle) {
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float32 rFm = getSingleConstant(Fm);
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float32 rFn = fpa11->fpreg[Fn].fSingle;
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if (float32_is_nan(rFn))
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goto unordered;
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if (n_flag)
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rFm ^= 0x80000000;
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/* test for less than condition */
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if (float32_lt_nocheck(rFn, rFm))
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flags |= CC_NEGATIVE;
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/* test for equal condition */
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if (float32_eq_nocheck(rFn, rFm))
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flags |= CC_ZERO;
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/* test for greater than or equal condition */
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if (float32_lt_nocheck(rFm, rFn))
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flags |= CC_CARRY;
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} else {
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float64 rFm = getDoubleConstant(Fm);
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float64 rFn = fpa11->fpreg[Fn].fDouble;
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if (float64_is_nan(rFn))
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goto unordered;
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if (n_flag)
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rFm ^= 0x8000000000000000ULL;
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/* test for less than condition */
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if (float64_lt_nocheck(rFn, rFm))
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flags |= CC_NEGATIVE;
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/* test for equal condition */
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if (float64_eq_nocheck(rFn, rFm))
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flags |= CC_ZERO;
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/* test for greater than or equal condition */
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if (float64_lt_nocheck(rFm, rFn))
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flags |= CC_CARRY;
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}
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} else {
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/* Both operands are in registers. */
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if (fpa11->fType[Fn] == typeSingle
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&& fpa11->fType[Fm] == typeSingle) {
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float32 rFm = fpa11->fpreg[Fm].fSingle;
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float32 rFn = fpa11->fpreg[Fn].fSingle;
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if (float32_is_nan(rFn)
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|| float32_is_nan(rFm))
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goto unordered;
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if (n_flag)
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rFm ^= 0x80000000;
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/* test for less than condition */
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if (float32_lt_nocheck(rFn, rFm))
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flags |= CC_NEGATIVE;
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/* test for equal condition */
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if (float32_eq_nocheck(rFn, rFm))
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flags |= CC_ZERO;
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/* test for greater than or equal condition */
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if (float32_lt_nocheck(rFm, rFn))
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flags |= CC_CARRY;
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} else {
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/* Promote 32-bit operand to 64 bits. */
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float64 rFm, rFn;
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rFm = (fpa11->fType[Fm] == typeSingle) ?
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float32_to_float64(fpa11->fpreg[Fm].fSingle)
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: fpa11->fpreg[Fm].fDouble;
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rFn = (fpa11->fType[Fn] == typeSingle) ?
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float32_to_float64(fpa11->fpreg[Fn].fSingle)
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: fpa11->fpreg[Fn].fDouble;
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if (float64_is_nan(rFn)
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|| float64_is_nan(rFm))
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goto unordered;
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if (n_flag)
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rFm ^= 0x8000000000000000ULL;
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/* test for less than condition */
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if (float64_lt_nocheck(rFn, rFm))
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flags |= CC_NEGATIVE;
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/* test for equal condition */
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if (float64_eq_nocheck(rFn, rFm))
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flags |= CC_ZERO;
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/* test for greater than or equal condition */
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if (float64_lt_nocheck(rFm, rFn))
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flags |= CC_CARRY;
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}
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}
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#endif
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writeConditionCodes(flags);
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return 1;
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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())
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flags |= CC_CARRY;
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if (e_flag)
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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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