// SPDX-License-Identifier: GPL-2.0
|
/*---------------------------------------------------------------------------+
|
| reg_mul.c |
|
| |
|
| Multiply one FPU_REG by another, put the result in a destination FPU_REG. |
|
| |
|
| Copyright (C) 1992,1993,1997 |
|
| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
|
| E-mail billm@suburbia.net |
|
| |
|
| Returns the tag of the result if no exceptions or errors occurred. |
|
| |
|
+---------------------------------------------------------------------------*/
|
|
/*---------------------------------------------------------------------------+
|
| The destination may be any FPU_REG, including one of the source FPU_REGs. |
|
+---------------------------------------------------------------------------*/
|
|
#include "fpu_emu.h"
|
#include "exception.h"
|
#include "reg_constant.h"
|
#include "fpu_system.h"
|
|
/*
|
Multiply two registers to give a register result.
|
The sources are st(deststnr) and (b,tagb,signb).
|
The destination is st(deststnr).
|
*/
|
/* This routine must be called with non-empty source registers */
|
int FPU_mul(FPU_REG const *b, u_char tagb, int deststnr, int control_w)
|
{
|
FPU_REG *a = &st(deststnr);
|
FPU_REG *dest = a;
|
u_char taga = FPU_gettagi(deststnr);
|
u_char saved_sign = getsign(dest);
|
u_char sign = (getsign(a) ^ getsign(b));
|
int tag;
|
|
if (!(taga | tagb)) {
|
/* Both regs Valid, this should be the most common case. */
|
|
tag =
|
FPU_u_mul(a, b, dest, control_w, sign,
|
exponent(a) + exponent(b));
|
if (tag < 0) {
|
setsign(dest, saved_sign);
|
return tag;
|
}
|
FPU_settagi(deststnr, tag);
|
return tag;
|
}
|
|
if (taga == TAG_Special)
|
taga = FPU_Special(a);
|
if (tagb == TAG_Special)
|
tagb = FPU_Special(b);
|
|
if (((taga == TAG_Valid) && (tagb == TW_Denormal))
|
|| ((taga == TW_Denormal) && (tagb == TAG_Valid))
|
|| ((taga == TW_Denormal) && (tagb == TW_Denormal))) {
|
FPU_REG x, y;
|
if (denormal_operand() < 0)
|
return FPU_Exception;
|
|
FPU_to_exp16(a, &x);
|
FPU_to_exp16(b, &y);
|
tag = FPU_u_mul(&x, &y, dest, control_w, sign,
|
exponent16(&x) + exponent16(&y));
|
if (tag < 0) {
|
setsign(dest, saved_sign);
|
return tag;
|
}
|
FPU_settagi(deststnr, tag);
|
return tag;
|
} else if ((taga <= TW_Denormal) && (tagb <= TW_Denormal)) {
|
if (((tagb == TW_Denormal) || (taga == TW_Denormal))
|
&& (denormal_operand() < 0))
|
return FPU_Exception;
|
|
/* Must have either both arguments == zero, or
|
one valid and the other zero.
|
The result is therefore zero. */
|
FPU_copy_to_regi(&CONST_Z, TAG_Zero, deststnr);
|
/* The 80486 book says that the answer is +0, but a real
|
80486 behaves this way.
|
IEEE-754 apparently says it should be this way. */
|
setsign(dest, sign);
|
return TAG_Zero;
|
}
|
/* Must have infinities, NaNs, etc */
|
else if ((taga == TW_NaN) || (tagb == TW_NaN)) {
|
return real_2op_NaN(b, tagb, deststnr, &st(0));
|
} else if (((taga == TW_Infinity) && (tagb == TAG_Zero))
|
|| ((tagb == TW_Infinity) && (taga == TAG_Zero))) {
|
return arith_invalid(deststnr); /* Zero*Infinity is invalid */
|
} else if (((taga == TW_Denormal) || (tagb == TW_Denormal))
|
&& (denormal_operand() < 0)) {
|
return FPU_Exception;
|
} else if (taga == TW_Infinity) {
|
FPU_copy_to_regi(a, TAG_Special, deststnr);
|
setsign(dest, sign);
|
return TAG_Special;
|
} else if (tagb == TW_Infinity) {
|
FPU_copy_to_regi(b, TAG_Special, deststnr);
|
setsign(dest, sign);
|
return TAG_Special;
|
}
|
#ifdef PARANOID
|
else {
|
EXCEPTION(EX_INTERNAL | 0x102);
|
return FPU_Exception;
|
}
|
#endif /* PARANOID */
|
|
return 0;
|
}
|
