mirror of https://github.com/Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
116 lines
3.9 KiB
116 lines
3.9 KiB
// 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 [email protected] | |
|
| | |
|
| 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; |
|
}
|
|
|