fpa11.c

一个2.4.21版本的嵌入式linux内核

/*
    NetWinder Floating Point Emulator
    (c) Rebel.COM, 1998,1999
    (c) Philip Blundell, 2001

    Direct questions, comments to Scott Bambrough <[e-mail]>

    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"

#include "fpmodule.h"
#include "fpmodule.inl"

#include <asm/system.h>

/* forward declarations */
unsigned int EmulateCPDO(const unsigned int);
unsigned int EmulateCPDT(const unsigned int);
unsigned int EmulateCPRT(const unsigned int);

/* Reset the FPA11 chip.  Called to initialize and reset the emulator. */
void resetFPA11(void)
{
	int i;
	FPA11 *fpa11 = GET_FPA11();

	/* initialize the register type array */
	for (i = 0; i <= 7; i++) {
		fpa11->fType[i] = typeNone;
	}

	/* FPSR: set system id to FP_EMULATOR, set AC, clear all other bits */
	fpa11->fpsr = FP_EMULATOR | BIT_AC;
}

void SetRoundingMode(const unsigned int opcode)
{
	switch (opcode & MASK_ROUNDING_MODE) {
	default:
	case ROUND_TO_NEAREST:
		float_rounding_mode = float_round_nearest_even;
		break;

	case ROUND_TO_PLUS_INFINITY:
		float_rounding_mode = float_round_up;
		break;

	case ROUND_TO_MINUS_INFINITY:
		float_rounding_mode = float_round_down;
		break;

	case ROUND_TO_ZERO:
		float_rounding_mode = float_round_to_zero;
		break;
	}
}

void SetRoundingPrecision(const unsigned int opcode)
{
#ifdef CONFIG_FPE_NWFPE_XP
	switch (opcode & MASK_ROUNDING_PRECISION) {
	case ROUND_SINGLE:
		floatx80_rounding_precision = 32;
		break;

	case ROUND_DOUBLE:
		floatx80_rounding_precision = 64;
		break;

	case ROUND_EXTENDED:
		floatx80_rounding_precision = 80;
		break;

	default:
		floatx80_rounding_precision = 80;
	}
#endif
}

void nwfpe_init_fpa(void)
{
	FPA11 *fpa11 = GET_FPA11();
#ifdef NWFPE_DEBUG
	printk("NWFPE: setting up state.\n");
#endif
	resetFPA11();
	SetRoundingMode(ROUND_TO_NEAREST);
	SetRoundingPrecision(ROUND_EXTENDED);
	fpa11->initflag = 1;
}

/* Emulate the instruction in the opcode. */
unsigned int EmulateAll(const unsigned int opcode)
{
#ifdef NWFPE_DEBUG
	printk("NWFPE: emulating opcode %08x\n", opcode);
#endif

	if (TEST_OPCODE(opcode, MASK_CPRT)) {
		/* Emulate conversion opcodes. */
		/* Emulate register transfer opcodes. */
		/* Emulate comparison opcodes. */
		return EmulateCPRT(opcode);
	} else if (TEST_OPCODE(opcode, MASK_CPDO)) {
		/* Emulate monadic arithmetic opcodes. */
		/* Emulate dyadic arithmetic opcodes. */
		return EmulateCPDO(opcode);
	} else if (TEST_OPCODE(opcode, MASK_CPDT)) {
		/* Emulate load/store opcodes. */
		/* Emulate load/store multiple opcodes. */
		return EmulateCPDT(opcode);
	}

	/* Invalid instruction detected.  Return FALSE. */
	return 0;
}