b091e00899
handler CVS ----------------------------------------------------------------------
147 lines
3.8 KiB
C
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);
|
|
|
|
}
|