/*-------------------------------------------------------------------------
_fsmul.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>
#ifdef FLOAT_ASM_MCS51
// float __fsmul (float a, float b) __reentrant
static void dummy(void) __naked
{
__asm
.globl ___fsmul
___fsmul:
// 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
lcall fsgetargs
// first check if either input is zero
cjne r4, #0, 00002$
00001$:
ljmp fs_return_zero
00002$:
mov a, r7
jz 00001$
// compute final sign bit
jnb sign_b, 00003$
cpl sign_a
00003$:
// check if either input is infinity
mov a, exp_b
cjne a, #0xFF, 00004$
ljmp fs_return_inf
00004$:
mov a, exp_a
cjne a, #0xFF, 00005$
ljmp fs_return_inf
00005$:
// add the exponents
add a, exp_b
// if carry then no underflow
jc 00006$
add a, #130
jc 00007$
ljmp fs_return_zero
00006$:
add a, #131
dec a
jnc 00007$
ljmp fs_return_inf
00007$:
mov exp_a, a
// now we need to multipy r4/r3/r2 * r7/r6/r5
// ------------------------------------------
// r2 * r5 << 0
// r3 * r5 + r2 * r6 << 8
// r4 * r5 + r3 * r6 + r2 * r7 << 16
// r4 * r6 + r3 * r7 << 24
// r4 * r7 << 32
//
// This adds quite a bit of code, but it is a LOT faster
// than three calls to __mululong...
// output goes into r4/r3/r2/r1/r0/xx
mov a, r2
mov b, r5
mul ab // r2 * r5
// discard lowest 8 bits
mov r0, b
// range 0-FE
mov a, r2
mov b, r6
mul ab // r2 * r6
add a, r0
mov r0, a
clr a
addc a, b
mov r1, a
// range 0-FEFF
mov a, r3
mov b, r5
mul ab // r3 * r5
add a, r0
// discard lowest 8 bits
mov a, r1
addc a, b
mov r1, a
clr a
rlc a
xch a, r2
// range 0-1FD
mov b, r7
mul ab // r2 * r7
add a, r1
mov r1, a
mov a, r2
addc a, b
mov r2, a
// range 0-FFFE
mov a, r3
mov r0, a
mov b, r6
mul ab // r3 * r6
add a, r1
mov r1, a
mov a, r2
addc a, b
mov r2, a
clr a
rlc a
mov r3, a
// range 0-1FDFF
mov a, r4
mov b, r5
mul ab // r4 * r5
add a, r1
mov r1, a
mov a, r2
addc a, b
mov r2, a
clr a
addc a, r3
mov r3, a
// range 0-2FC00
mov a, r0 // r3
mov b, r7
mul ab // r3 * r7
add a, r2
mov r2, a
mov a, r3
addc a, b
mov r3, a
clr a
rlc a
xch a, r4
// range 0-100FD00
mov r5, a
mov b, r6
mul ab // r4 * r6
add a, r2
mov r2, a
mov a, r3
addc a, b
mov r3, a
clr a
addc a, r4
mov r4, a
// range 0-1FEFE00
mov a, r5 // r4
mov b, r7
mul ab // r4 * r7
add a, r3
mov r3, a
mov a, r4
addc a, b
mov r4, a
// range 40000000-FFFFFE00
jb acc.7, 00010$
lcall fs_normalize_a
00010$:
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
*/
/* (c)2000/2001: hacked a little by johan.knol@iduna.nl for sdcc */
union float_long
{
float f;
unsigned long l;
};
/* multiply two floats */
float __fsmul (float a1, float a2) {
volatile union float_long fl1, fl2;
volatile unsigned long result;
char sign;
fl1.f = a1;
fl2.f = a2;
if (!fl1.l || !fl2.l)
return (0);
/* compute sign and exponent */
sign = SIGN (fl1.l) ^ SIGN (fl2.l);
exp = EXP
(fl1.
l) - EXCESS
;
fl1.l = MANT (fl1.l);
fl2.l = MANT (fl2.l);
/* the multiply is done as one 16x16 multiply and two 16x8 multiplies */
result = (unsigned long)((unsigned short)(fl1.l >> 8)) * (unsigned short)(fl2.l >> 8);
result += ((unsigned long)((unsigned short)(fl1.l & 0xff)) * (unsigned short)(fl2.l >> 8)) >> 8;
result += ((unsigned long)((unsigned short)(fl2.l & 0xff)) * (unsigned short)(fl1.l >> 8)) >> 8;
/* round, phase 1 */
result += 0x40;
if (result & SIGNBIT)
{
/* round, phase 2 */
result += 0x40;
result >>= 8;
}
else
{
result >>= 7;
exp--;
}
result &= ~HIDDEN;
/* pack up and go home */
fl1.l = (sign ? SIGNBIT : 0) | __INFINITY;
fl1.l = 0;
else
fl1.
l = PACK
(sign
? SIGNBIT
: 0 , exp, result
); return (fl1.f);
}
#endif