linux cp fp,代码阅读 - Linux\kernel\linux-5.0\arch\arm\nwfpe\fpa11

NetWinder Floating Point Emulator

Direct questions, comments to Scott Bambrough 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 "fpopcode.h"

unsigned int SingleCPDO(struct roundingData *roundData, const unsigned int opcode, FPREG * rFd);

unsigned int DoubleCPDO(struct roundingData *roundData, const unsigned int opcode, FPREG * rFd);

unsigned int ExtendedCPDO(struct roundingData *roundData, const unsigned int opcode, FPREG * rFd);

unsigned int EmulateCPDO(const unsigned int opcode)

{

FPA11 *fpa11 = GET_FPA11();

FPREG *rFd;

unsigned int nType, nDest, nRc;

struct roundingData roundData;

/* Get the destination size. If not valid let Linux perform

an invalid instruction trap. */

nDest = getDestinationSize(opcode);

if (typeNone == nDest)

return 0;

roundData.mode = SetRoundingMode(opcode);

roundData.precision = SetRoundingPrecision(opcode);

roundData.exception = 0;

/* Compare the size of the operands in Fn and Fm.

Choose the largest size and perform operations in that size,

in order to make use of all the precision of the operands.

If Fm is a constant, we just grab a constant of a size

matching the size of the operand in Fn. */

if (MONADIC_INSTRUCTION(opcode))

nType = nDest;

else

nType = fpa11->fType[getFn(opcode)];

if (!CONSTANT_FM(opcode)) {

if (nType < fpa11->fType[Fm]) {

nType = fpa11->fType[Fm];

}

rFd = &fpa11->fpreg[getFd(opcode)];

switch (nType) {

case typeSingle:

nRc = SingleCPDO(&roundData, opcode, rFd);

break;

case typeDouble:

nRc = DoubleCPDO(&roundData, opcode, rFd);

break;

#ifdef CONFIG_FPE_NWFPE_XP

case typeExtended:

nRc = ExtendedCPDO(&roundData, opcode, rFd);

break;

#endif

default:

nRc = 0;

}

/* The CPDO functions used to always set the destination type

to be the same as their working size. */

if (nRc != 0) {

/* If the operation succeeded, check to see if the result in the

destination register is the correct size. If not force it

to be. */

fpa11->fType[getFd(opcode)] = nDest;

#ifdef CONFIG_FPE_NWFPE_XP

if (nDest != nType) {

switch (nDest) {

case typeSingle:

{

if (typeDouble == nType)

rFd->fSingle = float64_to_float32(&roundData, rFd->fDouble);

else

rFd->fSingle = floatx80_to_float32(&roundData, rFd->fExtended);

}

break;

case typeDouble:

{

if (typeSingle == nType)

rFd->fDouble = float32_to_float64(rFd->fSingle);

else

rFd->fDouble = floatx80_to_float64(&roundData, rFd->fExtended);

}

break;

case typeExtended:

{

if (typeSingle == nType)

rFd->fExtended = float32_to_floatx80(rFd->fSingle);

else

rFd->fExtended = float64_to_floatx80(rFd->fDouble);

}

break;

}

#else

if (nDest != nType) {

if (nDest == typeSingle)

rFd->fSingle = float64_to_float32(&roundData, rFd->fDouble);

else

rFd->fDouble = float32_to_float64(rFd->fSingle);

}

#endif

}

if (roundData.exception)

float_raise(roundData.exception);

return nRc;

}

linux cp fp,代码阅读 - Linux\kernel\linux-5.0\arch\arm\nwfpe\fpa11_cpdo.c