1 /* Floating point library in optimized assembly for 8051
2 * Copyright (c) 2004, Paul Stoffregen, paul@pjrc.com
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Library General Public License
6 * as published by the Free Software Foundation; either version 2
7 * of the License, or (at your option) any later version.
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
20 #define SDCC_FLOAT_LIB
24 #ifdef FLOAT_ASM_MCS51
26 // float __fsmul (float a, float b) reentrant
27 static void dummy(void) _naked
32 // extract the two inputs, placing them into:
33 // sign exponent mantissa
34 // ---- -------- --------
35 // a: sign_a exp_a r4/r3/r2
36 // b: sign_b exp_b r7/r6/r5
40 // first check if either input is zero
49 // compute final sign bit
61 // now we need to multipy r4/r3/r2 * r7/r6/r5
62 // ------------------------------------------
64 // r3 * r5 + r2 * r6 << 8
65 // r4 * r5 + r3 * r6 + r2 * r7 << 16
66 // r4 * r6 + r3 * r7 << 24
69 // This adds quite a bit of code, but it is a LOT faster
70 // than three calls to __mululong...
72 // output goes into r4/r3/r2/r1/r0/xx
77 // discard lowest 8 bits
95 // discard lowest 8 bits
174 // range 40000000-FFFFFE00
180 ljmp fs_round_and_return
188 ** libgcc support for software floating point.
189 ** Copyright (C) 1991 by Pipeline Associates, Inc. All rights reserved.
190 ** Permission is granted to do *anything* you want with this file,
191 ** commercial or otherwise, provided this message remains intact. So there!
192 ** I would appreciate receiving any updates/patches/changes that anyone
193 ** makes, and am willing to be the repository for said changes (am I
194 ** making a big mistake?).
197 ** Pipeline Associates, Inc.
198 ** pipeline!phw@motown.com or
199 ** sun!pipeline!phw or
200 ** uunet!motown!pipeline!phw
203 /* (c)2000/2001: hacked a little by johan.knol@iduna.nl for sdcc */
212 /* multiply two floats */
213 float __fsmul (float a1, float a2) {
214 volatile union float_long fl1, fl2;
215 volatile unsigned long result;
222 if (!fl1.l || !fl2.l)
225 /* compute sign and exponent */
226 sign = SIGN (fl1.l) ^ SIGN (fl2.l);
227 exp = EXP (fl1.l) - EXCESS;
230 fl1.l = MANT (fl1.l);
231 fl2.l = MANT (fl2.l);
233 /* the multiply is done as one 16x16 multiply and two 16x8 multiples */
234 result = (fl1.l >> 8) * (fl2.l >> 8);
235 result += ((fl1.l & (unsigned long) 0xFF) * (fl2.l >> 8)) >> 8;
236 result += ((fl2.l & (unsigned long) 0xFF) * (fl1.l >> 8)) >> 8;
238 if (result & SIGNBIT)
254 /* pack up and go home */
255 fl1.l = PACK (sign ? SIGNBIT : 0 , (unsigned long)exp, result);