Bochs/bochs/fpu/reg_u_add.c
Stanislav Shwartsman b091e00899 Exclude INTERNAL FPU errors handling outside of standart FPU exceptions
handler
CVS ----------------------------------------------------------------------
2003-10-04 12:32:56 +00:00

147 lines
3.8 KiB
C

/*---------------------------------------------------------------------------+
| reg_u_add.c |
| $Id: reg_u_add.c,v 1.5 2003-10-04 12:32:56 sshwarts Exp $
| |
| Add two valid (TAG_Valid) FPU_REG numbers, of the same sign, and put the |
| result in a destination FPU_REG. |
| |
| Copyright (C) 1992,1993,1995,1997,1999 |
| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
| E-mail billm@melbpc.org.au |
| |
| Return value is the tag of the answer, or-ed with FPU_Exception if |
| one was raised, or -1 on internal error. |
| |
+---------------------------------------------------------------------------*/
/*
| Kernel addition routine FPU_u_add(reg *arg1, reg *arg2, reg *answ).
| Takes two valid reg f.p. numbers (TAG_Valid), which are
| treated as unsigned numbers,
| and returns their sum as a TAG_Valid or TAG_Special f.p. number.
| The returned number is normalized.
| Basic checks are performed if PARANOID is defined.
*/
#include "exception.h"
#include "fpu_emu.h"
#include "control_w.h"
int FPU_u_add(const FPU_REG *arg1, const FPU_REG *arg2, FPU_REG *answ,
u16 control_w, u_char sign, s32 expa, s32 expb)
{
const FPU_REG *rtmp;
FPU_REG shifted;
u32 extent = 0;
int ediff = expa - expb, ed2, eflag, ovfl, carry;
if (ediff < 0)
{
ediff = -ediff;
rtmp = arg1;
arg1 = arg2;
arg2 = rtmp;
expa = expb;
}
/* Now we have exponent of arg1 >= exponent of arg2 */
answ->exp = expa;
#ifdef PARANOID
if (!(arg1->sigh & 0x80000000) || !(arg2->sigh & 0x80000000))
{
INTERNAL(0x201);
return -1;
}
#endif
if (ediff == 0)
{
extent = 0;
shifted.sigl = arg2->sigl;
shifted.sigh = arg2->sigh;
}
else if (ediff < 32)
{
ed2 = 32 - ediff;
extent = arg2->sigl << ed2;
shifted.sigl = arg2->sigl >> ediff;
shifted.sigl |= (arg2->sigh << ed2);
shifted.sigh = arg2->sigh >> ediff;
}
else if (ediff < 64)
{
ediff -= 32;
if (! ediff)
{
eflag = 0;
extent = arg2->sigl;
shifted.sigl = arg2->sigh;
}
else
{
u32 extent2;
ed2 = 32 - ediff;
eflag = arg2->sigl;
if (eflag)
extent |= 1;
extent2 = arg2->sigl >> ediff;
extent2 |= (arg2->sigh << ed2);
extent |= extent2;
shifted.sigl = arg2->sigh >> ediff;
}
shifted.sigh = 0;
}
else
{
ediff -= 64;
if (! ediff)
{
eflag = arg2->sigl;
extent = arg2->sigh;
}
else
{
eflag = arg2->sigl | arg2->sigh;
if (ediff < 32)
extent = arg2->sigh >> ediff;
else
extent = 0;
}
shifted.sigl = 0;
shifted.sigh = 0;
if (eflag)
extent |= 1;
}
answ->sigh = arg1->sigh + shifted.sigh;
ovfl = shifted.sigh > answ->sigh;
answ->sigl = arg1->sigl + shifted.sigl;
if (shifted.sigl > answ->sigl)
{
answ->sigh ++;
if (answ->sigh == 0)
ovfl = 1;
}
if (ovfl)
{
carry = extent & 1;
extent >>= 1;
extent |= carry;
if (answ->sigl & 1)
extent |= 0x80000000;
answ->sigl >>= 1;
if (answ->sigh & 1)
answ->sigl |= 0x80000000;
answ->sigh >>= 1;
answ->sigh |= 0x80000000;
answ->exp ++;
}
return FPU_round(answ, extent, 0, control_w, sign);
}