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