errors.c

freebsd v4.4内核源码

	      0x213  in wm_sqrt.S
	      0x214  in wm_sqrt.S
	      0x215  in wm_sqrt.S
	      0x216  in reg_round.S
	      0x217  in reg_round.S
	      0x218  in reg_round.S
 */

void
exception(int n)
{
	int     i, int_type;

	int_type = 0;		/* Needed only to stop compiler warnings */
	if (n & EX_INTERNAL) {
		int_type = n - EX_INTERNAL;
		n = EX_INTERNAL;
		/* Set lots of exception bits! */
		status_word |= (SW_Exc_Mask | SW_Summary | FPU_BUSY);
	} else {
		/* Extract only the bits which we use to set the status word */
		n &= (SW_Exc_Mask);
		/* Set the corresponding exception bit */
		status_word |= n;
		if (status_word & ~control_word & CW_Exceptions)
			status_word |= SW_Summary;
		if (n & (SW_Stack_Fault | EX_Precision)) {
			if (!(n & SW_C1))
				/* This bit distinguishes over- from underflow
				 * for a stack fault, and roundup from
				 * round-down for precision loss. */
				status_word &= ~SW_C1;
		}
	}

	REENTRANT_CHECK(OFF);
	if ((~control_word & n & CW_Exceptions) || (n == EX_INTERNAL)) {
#ifdef PRINT_MESSAGES
		/* My message from the sponsor */
		printf(FPU_VERSION " " __DATE__ " (C) W. Metzenthen.\n");
#endif				/* PRINT_MESSAGES */

		/* Get a name string for error reporting */
		for (i = 0; exception_names[i].type; i++)
			if ((exception_names[i].type & n) == exception_names[i].type)
				break;

		if (exception_names[i].type) {
#ifdef PRINT_MESSAGES
			printf("FP Exception: %s!\n", exception_names[i].name);
#endif				/* PRINT_MESSAGES */
		} else
			printf("FP emulator: Unknown Exception: 0x%04x!\n", n);

		if (n == EX_INTERNAL) {
			printf("FP emulator: Internal error type 0x%04x\n", int_type);
			emu_printall();
		}
#ifdef PRINT_MESSAGES
		else
			emu_printall();
#endif				/* PRINT_MESSAGES */

		/* The 80486 generates an interrupt on the next non-control
		 * FPU instruction. So we need some means of flagging it. We
		 * use the ES (Error Summary) bit for this, assuming that this
		 * is the way a real FPU does it (until I can check it out),
		 * if not, then some method such as the following kludge might
		 * be needed. */
/*      regs[0].tag |= TW_FPU_Interrupt; */
	}
	REENTRANT_CHECK(ON);

#ifdef __DEBUG__
	math_abort(SIGFPE);
#endif				/* __DEBUG__ */

}


/* Real operation attempted on two operands, one a NaN */
void
real_2op_NaN(FPU_REG * a, FPU_REG * b, FPU_REG * dest)
{
	FPU_REG *x;
	int     signalling;

	x = a;
	if (a->tag == TW_NaN) {
		if (b->tag == TW_NaN) {
			signalling = !(a->sigh & b->sigh & 0x40000000);
			/* find the "larger" */
			if (*(long long *) &(a->sigl) < *(long long *) &(b->sigl))
				x = b;
		} else {
			/* return the quiet version of the NaN in a */
			signalling = !(a->sigh & 0x40000000);
		}
	} else
#ifdef PARANOID
		if (b->tag == TW_NaN)
#endif				/* PARANOID */
		{
			signalling = !(b->sigh & 0x40000000);
			x = b;
		}
#ifdef PARANOID
		else {
			signalling = 0;
			EXCEPTION(EX_INTERNAL | 0x113);
			x = &CONST_QNaN;
		}
#endif				/* PARANOID */

	if (!signalling) {
		if (!(x->sigh & 0x80000000))	/* pseudo-NaN ? */
			x = &CONST_QNaN;
		reg_move(x, dest);
		return;
	}
	if (control_word & CW_Invalid) {
		/* The masked response */
		if (!(x->sigh & 0x80000000))	/* pseudo-NaN ? */
			x = &CONST_QNaN;
		reg_move(x, dest);
		/* ensure a Quiet NaN */
		dest->sigh |= 0x40000000;
	}
	EXCEPTION(EX_Invalid);

	return;
}
/* Invalid arith operation on Valid registers */
void
arith_invalid(FPU_REG * dest)
{

	if (control_word & CW_Invalid) {
		/* The masked response */
		reg_move(&CONST_QNaN, dest);
	}
	EXCEPTION(EX_Invalid);

	return;

}


/* Divide a finite number by zero */
void
divide_by_zero(int sign, FPU_REG * dest)
{

	if (control_word & CW_ZeroDiv) {
		/* The masked response */
		reg_move(&CONST_INF, dest);
		dest->sign = (unsigned char) sign;
	}
	EXCEPTION(EX_ZeroDiv);

	return;

}


/* This may be called often, so keep it lean */
void
set_precision_flag_up(void)
{
	if (control_word & CW_Precision)
		status_word |= (SW_Precision | SW_C1);	/* The masked response */
	else
		exception(EX_Precision | SW_C1);

}


/* This may be called often, so keep it lean */
void
set_precision_flag_down(void)
{
	if (control_word & CW_Precision) {	/* The masked response */
		status_word &= ~SW_C1;
		status_word |= SW_Precision;
	} else
		exception(EX_Precision);
}


int
denormal_operand(void)
{
	if (control_word & CW_Denormal) {	/* The masked response */
		status_word |= SW_Denorm_Op;
		return 0;
	} else {
		exception(EX_Denormal);
		return 1;
	}
}


void
arith_overflow(FPU_REG * dest)
{

	if (control_word & CW_Overflow) {
		char    sign;
		/* The masked response */
/* **** The response here depends upon the rounding mode */
		sign = dest->sign;
		reg_move(&CONST_INF, dest);
		dest->sign = sign;
	} else {
		/* Subtract the magic number from the exponent */
		dest->exp -= (3 * (1 << 13));
	}

	/* By definition, precision is lost. It appears that the roundup bit
	 * (C1) is also set by convention. */
	EXCEPTION(EX_Overflow | EX_Precision | SW_C1);

	return;

}


void
arith_underflow(FPU_REG * dest)
{

	if (control_word & CW_Underflow) {
		/* The masked response */
		if (dest->exp <= EXP_UNDER - 63)
			reg_move(&CONST_Z, dest);
	} else {
		/* Add the magic number to the exponent */
		dest->exp += (3 * (1 << 13));
	}

	EXCEPTION(EX_Underflow);

	return;
}


void
stack_overflow(void)
{

	if (control_word & CW_Invalid) {
		/* The masked response */
		top--;
		reg_move(&CONST_QNaN, FPU_st0_ptr = &st(0));
	}
	EXCEPTION(EX_StackOver);

	return;

}


void
stack_underflow(void)
{

	if (control_word & CW_Invalid) {
		/* The masked response */
		reg_move(&CONST_QNaN, FPU_st0_ptr);
	}
	EXCEPTION(EX_StackUnder);

	return;

}


void
stack_underflow_i(int i)
{

	if (control_word & CW_Invalid) {
		/* The masked response */
		reg_move(&CONST_QNaN, &(st(i)));
	}
	EXCEPTION(EX_StackUnder);

	return;

}


void
stack_underflow_pop(int i)
{

	if (control_word & CW_Invalid) {
		/* The masked response */
		reg_move(&CONST_QNaN, &(st(i)));
		pop();
	}
	EXCEPTION(EX_StackUnder);

	return;

}