/*-------------------------------------------------------------------------
_fsadd.c - Floating point library in optimized assembly for 8051
Copyright (c) 2004, Paul Stoffregen, paul@pjrc.com
This library 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 library 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 library; see the file COPYING. If not, write to the
Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
MA 02110-1301, USA.
As a special exception, if you link this library with other files,
some of which are compiled with SDCC, to produce an executable,
this library does not by itself cause the resulting executable to
be covered by the GNU General Public License. This exception does
not however invalidate any other reasons why the executable file
might be covered by the GNU General Public License.
-------------------------------------------------------------------------*/
#define __SDCC_FLOAT_LIB
#include <float.h>
#include <stdbool.h>
#include <sdcc-lib.h>
#ifdef FLOAT_ASM_MCS51
// float __fsadd (float a, float b) __reentrant
static void dummy(void) __naked
{
__asm
// extract the two inputs, placing them into:
// sign exponent mantissa
// ---- -------- --------
// a: sign_a exp_a r4/r3/r2
// b: sign_b exp_b r7/r6/r5
//
// r1: used to extend precision of a's mantissa
// r0: general purpose loop counter
.globl ___fsadd
___fsadd:
lcall fsgetargs
.globl fsadd_direct_entry
fsadd_direct_entry:
// we're going to extend mantissa to 32 bits temporarily
mov r1, #0
// which exponent is greater?
mov a, exp_b
cjne a, exp_a, 00005$
sjmp 00011$
00005$: jnc 00010$
// a's exponent was greater, so shift b's mantissa
lcall fs_swap_a_b
00010$:
// b's exponent was greater, so shift a's mantissa
mov a, exp_b
clr c
subb a, exp_a
lcall fs_rshift_a // acc has # of shifts to do
00011$:
// decide if we need to add or subtract
// sign_a and sign_b are stored in the flag bits of psw,
// so this little trick checks if the arguements have the
// same sign.
mov a, psw
swap a
xrl a, psw
jb acc.1, 00022$
00020$:
// add the mantissas (both positive or both negative)
mov a, r2
add a, r5
mov r2, a
mov a, r3
addc a, r6
mov r3, a
mov a, r4
addc a, r7
mov r4, a
// check for overflow past 24 bits
jnc 00021$
mov a, #1
lcall fs_rshift_a
mov a, r4
orl a, #0x80
mov r4, a
00021$:
ljmp fs_round_and_return
00022$:
// subtract the mantissas (one of them is negative)
clr c
mov a, r2
subb a, r5
mov r2, a
mov a, r3
subb a, r6
mov r3, a
mov a, r4
subb a, r7
mov r4, a
jnc 00025$
// if we get a negative result, turn it positive and
// flip the sign bit
clr c
clr a
subb a, r1
mov r1, a
clr a
subb a, r2
mov r2, a
clr a
subb a, r3
mov r3, a
clr a
subb a, r4
mov r4, a
cpl sign_a
00025$:
lcall fs_normalize_a
ljmp fs_round_and_return
__endasm;
}
#else
/*
** libgcc support for software floating point.
** Copyright (C) 1991 by Pipeline Associates, Inc. All rights reserved.
** Permission is granted to do *anything* you want with this file,
** commercial or otherwise, provided this message remains intact. So there!
** I would appreciate receiving any updates/patches/changes that anyone
** makes, and am willing to be the repository for said changes (am I
** making a big mistake?).
**
** Pat Wood
** Pipeline Associates, Inc.
** pipeline!phw@motown.com or
** sun!pipeline!phw or
** uunet!motown!pipeline!phw
*/
union float_long
{
float f;
unsigned long l;
};
/* add two floats */
float __fsadd (float a1, float a2)
{
long mant1, mant2;
long _AUTOMEM *pfl1;
long _AUTOMEM *pfl2;
int exp1, exp2, expd;
bool sign = false;
pfl2 = (long _AUTOMEM *)&a2;
exp2 = EXP (*pfl2);
mant2 = MANT (*pfl2) << 4;
if (SIGN (*pfl2))
mant2 = -mant2;
/* check for zero args */
if (!*pfl2)
return (a1);
pfl1 = (long _AUTOMEM *)&a1;
exp1 = EXP (*pfl1);
mant1 = MANT (*pfl1) << 4;
if (SIGN(*pfl1))
if (*pfl1 & 0x80000000)
mant1 = -mant1;
/* check for zero args */
if (!*pfl1)
return (a2);
expd = exp1 - exp2;
if (expd > 25)
return (a1);
if (expd < -25)
return (a2);
if (expd < 0)
{
expd = -expd;
exp1 += expd;
mant1 >>= expd;
}
else
{
mant2 >>= expd;
}
mant1 += mant2;
sign = false;
if (mant1 < 0)
{
mant1 = -mant1;
sign = true;
}
else if (!mant1)
return (0);
/* normalize */
while (mant1 < (HIDDEN<<4)) {
mant1 <<= 1;
exp1--;
}
/* round off */
while (mant1 & 0xf0000000) {
if (mant1&1)
mant1 += 2;
mant1 >>= 1;
exp1++;
}
/* turn off hidden bit */
mant1 &= ~(HIDDEN<<4);
/* pack up and go home */
if (exp1 >= 0x100)
*pfl1 = (sign ? (SIGNBIT | __INFINITY) : __INFINITY);
else if (exp1 < 0)
*pfl1 = 0;
else
*pfl1 = PACK (sign ? SIGNBIT : 0 , exp1, mant1>>4);
return (a1);
}
#endif