291 lines
7.9 KiB
C
291 lines
7.9 KiB
C
/*
|
|
* Linux/PA-RISC Project (http://www.parisc-linux.org/)
|
|
*
|
|
* Floating-point emulation code
|
|
* Copyright (C) 2001 Hewlett-Packard (Paul Bame) <bame@debian.org>
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2, or (at your option)
|
|
* any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
|
|
*/
|
|
/*
|
|
* BEGIN_DESC
|
|
*
|
|
* File:
|
|
* @(#) pa/spmath/sfrem.c $Revision: 1.1 $
|
|
*
|
|
* Purpose:
|
|
* Single Precision Floating-point Remainder
|
|
*
|
|
* External Interfaces:
|
|
* sgl_frem(srcptr1,srcptr2,dstptr,status)
|
|
*
|
|
* Internal Interfaces:
|
|
*
|
|
* Theory:
|
|
* <<please update with a overview of the operation of this file>>
|
|
*
|
|
* END_DESC
|
|
*/
|
|
|
|
|
|
|
|
#include "float.h"
|
|
#include "sgl_float.h"
|
|
|
|
/*
|
|
* Single Precision Floating-point Remainder
|
|
*/
|
|
|
|
int
|
|
sgl_frem (sgl_floating_point * srcptr1, sgl_floating_point * srcptr2,
|
|
sgl_floating_point * dstptr, unsigned int *status)
|
|
{
|
|
register unsigned int opnd1, opnd2, result;
|
|
register int opnd1_exponent, opnd2_exponent, dest_exponent, stepcount;
|
|
register boolean roundup = FALSE;
|
|
|
|
opnd1 = *srcptr1;
|
|
opnd2 = *srcptr2;
|
|
/*
|
|
* check first operand for NaN's or infinity
|
|
*/
|
|
if ((opnd1_exponent = Sgl_exponent(opnd1)) == SGL_INFINITY_EXPONENT) {
|
|
if (Sgl_iszero_mantissa(opnd1)) {
|
|
if (Sgl_isnotnan(opnd2)) {
|
|
/* invalid since first operand is infinity */
|
|
if (Is_invalidtrap_enabled())
|
|
return(INVALIDEXCEPTION);
|
|
Set_invalidflag();
|
|
Sgl_makequietnan(result);
|
|
*dstptr = result;
|
|
return(NOEXCEPTION);
|
|
}
|
|
}
|
|
else {
|
|
/*
|
|
* is NaN; signaling or quiet?
|
|
*/
|
|
if (Sgl_isone_signaling(opnd1)) {
|
|
/* trap if INVALIDTRAP enabled */
|
|
if (Is_invalidtrap_enabled())
|
|
return(INVALIDEXCEPTION);
|
|
/* make NaN quiet */
|
|
Set_invalidflag();
|
|
Sgl_set_quiet(opnd1);
|
|
}
|
|
/*
|
|
* is second operand a signaling NaN?
|
|
*/
|
|
else if (Sgl_is_signalingnan(opnd2)) {
|
|
/* trap if INVALIDTRAP enabled */
|
|
if (Is_invalidtrap_enabled())
|
|
return(INVALIDEXCEPTION);
|
|
/* make NaN quiet */
|
|
Set_invalidflag();
|
|
Sgl_set_quiet(opnd2);
|
|
*dstptr = opnd2;
|
|
return(NOEXCEPTION);
|
|
}
|
|
/*
|
|
* return quiet NaN
|
|
*/
|
|
*dstptr = opnd1;
|
|
return(NOEXCEPTION);
|
|
}
|
|
}
|
|
/*
|
|
* check second operand for NaN's or infinity
|
|
*/
|
|
if ((opnd2_exponent = Sgl_exponent(opnd2)) == SGL_INFINITY_EXPONENT) {
|
|
if (Sgl_iszero_mantissa(opnd2)) {
|
|
/*
|
|
* return first operand
|
|
*/
|
|
*dstptr = opnd1;
|
|
return(NOEXCEPTION);
|
|
}
|
|
/*
|
|
* is NaN; signaling or quiet?
|
|
*/
|
|
if (Sgl_isone_signaling(opnd2)) {
|
|
/* trap if INVALIDTRAP enabled */
|
|
if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
|
|
/* make NaN quiet */
|
|
Set_invalidflag();
|
|
Sgl_set_quiet(opnd2);
|
|
}
|
|
/*
|
|
* return quiet NaN
|
|
*/
|
|
*dstptr = opnd2;
|
|
return(NOEXCEPTION);
|
|
}
|
|
/*
|
|
* check second operand for zero
|
|
*/
|
|
if (Sgl_iszero_exponentmantissa(opnd2)) {
|
|
/* invalid since second operand is zero */
|
|
if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
|
|
Set_invalidflag();
|
|
Sgl_makequietnan(result);
|
|
*dstptr = result;
|
|
return(NOEXCEPTION);
|
|
}
|
|
|
|
/*
|
|
* get sign of result
|
|
*/
|
|
result = opnd1;
|
|
|
|
/*
|
|
* check for denormalized operands
|
|
*/
|
|
if (opnd1_exponent == 0) {
|
|
/* check for zero */
|
|
if (Sgl_iszero_mantissa(opnd1)) {
|
|
*dstptr = opnd1;
|
|
return(NOEXCEPTION);
|
|
}
|
|
/* normalize, then continue */
|
|
opnd1_exponent = 1;
|
|
Sgl_normalize(opnd1,opnd1_exponent);
|
|
}
|
|
else {
|
|
Sgl_clear_signexponent_set_hidden(opnd1);
|
|
}
|
|
if (opnd2_exponent == 0) {
|
|
/* normalize, then continue */
|
|
opnd2_exponent = 1;
|
|
Sgl_normalize(opnd2,opnd2_exponent);
|
|
}
|
|
else {
|
|
Sgl_clear_signexponent_set_hidden(opnd2);
|
|
}
|
|
|
|
/* find result exponent and divide step loop count */
|
|
dest_exponent = opnd2_exponent - 1;
|
|
stepcount = opnd1_exponent - opnd2_exponent;
|
|
|
|
/*
|
|
* check for opnd1/opnd2 < 1
|
|
*/
|
|
if (stepcount < 0) {
|
|
/*
|
|
* check for opnd1/opnd2 > 1/2
|
|
*
|
|
* In this case n will round to 1, so
|
|
* r = opnd1 - opnd2
|
|
*/
|
|
if (stepcount == -1 && Sgl_isgreaterthan(opnd1,opnd2)) {
|
|
Sgl_all(result) = ~Sgl_all(result); /* set sign */
|
|
/* align opnd2 with opnd1 */
|
|
Sgl_leftshiftby1(opnd2);
|
|
Sgl_subtract(opnd2,opnd1,opnd2);
|
|
/* now normalize */
|
|
while (Sgl_iszero_hidden(opnd2)) {
|
|
Sgl_leftshiftby1(opnd2);
|
|
dest_exponent--;
|
|
}
|
|
Sgl_set_exponentmantissa(result,opnd2);
|
|
goto testforunderflow;
|
|
}
|
|
/*
|
|
* opnd1/opnd2 <= 1/2
|
|
*
|
|
* In this case n will round to zero, so
|
|
* r = opnd1
|
|
*/
|
|
Sgl_set_exponentmantissa(result,opnd1);
|
|
dest_exponent = opnd1_exponent;
|
|
goto testforunderflow;
|
|
}
|
|
|
|
/*
|
|
* Generate result
|
|
*
|
|
* Do iterative subtract until remainder is less than operand 2.
|
|
*/
|
|
while (stepcount-- > 0 && Sgl_all(opnd1)) {
|
|
if (Sgl_isnotlessthan(opnd1,opnd2))
|
|
Sgl_subtract(opnd1,opnd2,opnd1);
|
|
Sgl_leftshiftby1(opnd1);
|
|
}
|
|
/*
|
|
* Do last subtract, then determine which way to round if remainder
|
|
* is exactly 1/2 of opnd2
|
|
*/
|
|
if (Sgl_isnotlessthan(opnd1,opnd2)) {
|
|
Sgl_subtract(opnd1,opnd2,opnd1);
|
|
roundup = TRUE;
|
|
}
|
|
if (stepcount > 0 || Sgl_iszero(opnd1)) {
|
|
/* division is exact, remainder is zero */
|
|
Sgl_setzero_exponentmantissa(result);
|
|
*dstptr = result;
|
|
return(NOEXCEPTION);
|
|
}
|
|
|
|
/*
|
|
* Check for cases where opnd1/opnd2 < n
|
|
*
|
|
* In this case the result's sign will be opposite that of
|
|
* opnd1. The mantissa also needs some correction.
|
|
*/
|
|
Sgl_leftshiftby1(opnd1);
|
|
if (Sgl_isgreaterthan(opnd1,opnd2)) {
|
|
Sgl_invert_sign(result);
|
|
Sgl_subtract((opnd2<<1),opnd1,opnd1);
|
|
}
|
|
/* check for remainder being exactly 1/2 of opnd2 */
|
|
else if (Sgl_isequal(opnd1,opnd2) && roundup) {
|
|
Sgl_invert_sign(result);
|
|
}
|
|
|
|
/* normalize result's mantissa */
|
|
while (Sgl_iszero_hidden(opnd1)) {
|
|
dest_exponent--;
|
|
Sgl_leftshiftby1(opnd1);
|
|
}
|
|
Sgl_set_exponentmantissa(result,opnd1);
|
|
|
|
/*
|
|
* Test for underflow
|
|
*/
|
|
testforunderflow:
|
|
if (dest_exponent <= 0) {
|
|
/* trap if UNDERFLOWTRAP enabled */
|
|
if (Is_underflowtrap_enabled()) {
|
|
/*
|
|
* Adjust bias of result
|
|
*/
|
|
Sgl_setwrapped_exponent(result,dest_exponent,unfl);
|
|
*dstptr = result;
|
|
/* frem is always exact */
|
|
return(UNDERFLOWEXCEPTION);
|
|
}
|
|
/*
|
|
* denormalize result or set to signed zero
|
|
*/
|
|
if (dest_exponent >= (1 - SGL_P)) {
|
|
Sgl_rightshift_exponentmantissa(result,1-dest_exponent);
|
|
}
|
|
else {
|
|
Sgl_setzero_exponentmantissa(result);
|
|
}
|
|
}
|
|
else Sgl_set_exponent(result,dest_exponent);
|
|
*dstptr = result;
|
|
return(NOEXCEPTION);
|
|
}
|