X-Git-Url: https://git.gag.com/?a=blobdiff_plain;f=device%2Flib%2F_fsadd.c;h=cb179c5e9644ccf75724580ac0226e478ab1b720;hb=a8a7fc8a514bc79114c6d76d6a6aeb885387478c;hp=be0b44fc1271bcf72646648275c481180a986c8b;hpb=b09af35f2f1cde7649d3ac4a6f5d2af6d97895a0;p=fw%2Fsdcc diff --git a/device/lib/_fsadd.c b/device/lib/_fsadd.c index be0b44fc..cb179c5e 100644 --- a/device/lib/_fsadd.c +++ b/device/lib/_fsadd.c @@ -1,25 +1,168 @@ -/* the following deal with IEEE single-precision numbers */ -#define EXCESS 126 -#define SIGNBIT ((unsigned long)0x80000000) -#define HIDDEN (unsigned long)(1 << 23) -#define SIGN(fp) ((fp >> (8*sizeof(fp)-1)) & 1) -#define EXP(fp) (((fp) >> 23) & (unsigned int)0x00FF) -#define MANT(fp) (((fp) & (unsigned long)0x007FFFFF) | HIDDEN) -#define PACK(s,e,m) ((s) | ((e) << 23) | (m)) +/* Floating point library in optimized assembly for 8051 + * Copyright (c) 2004, Paul Stoffregen, paul@pjrc.com + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU Library General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, 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 program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + */ + + +#define SDCC_FLOAT_LIB +#include + + +#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 mantiassa + // ---- -------- --------- + // 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 ave 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; - long l; + unsigned long l; }; + /* add two floats */ -float -__fsadd (float a1, float a2) +float __fsadd (float a1, float a2) { volatile long mant1, mant2; volatile union float_long fl1, fl2; volatile int exp1, exp2; - volatile long sign = 0; + char sign = 0; fl1.f = a1; fl2.f = a2; @@ -34,13 +177,12 @@ __fsadd (float a1, float a2) exp2 = EXP (fl2.l); if (exp1 > exp2 + 25) - return (fl1.l); + return (fl1.f); if (exp2 > exp1 + 25) - return (fl2.l); + return (fl2.f); - /* do everything in excess precision so's we can round later */ - mant1 = MANT (fl1.l) << 6; - mant2 = MANT (fl2.l) << 6; + mant1 = MANT (fl1.l); + mant2 = MANT (fl2.l); if (SIGN (fl1.l)) mant1 = -mant1; @@ -61,42 +203,36 @@ __fsadd (float a1, float a2) if (mant1 < 0) { mant1 = -mant1; - sign = SIGNBIT; + sign = 1; } else if (!mant1) return (0); - /* normalize up */ - while (!(mant1 & (unsigned long) 0xE0000000)) - { - mant1 <<= 1; - exp1--; - } + /* normalize */ + while (mant1>= 1 ; - exp1++; - } - - /* round to even */ - mant1 += (mant1 & (unsigned long)0x40) ? (unsigned long) 0x20 : (unsigned long) 0x1F; - - /* normalize down? */ - if (mant1 & (unsigned long)(1 << 30)) - { - mant1 >>= 1; - exp1++; - } - - /* lose extra precision */ - mant1 >>= 6; + /* round off */ + while (mant1 & 0xff000000) { + if (mant1&1) + mant1 += 2; + mant1 >>= 1; + exp1++; + } /* turn off hidden bit */ mant1 &= ~HIDDEN; /* pack up and go home */ - fl1.l = PACK (sign, (unsigned long) exp1, mant1); + if (exp1 >= 0x100) + fl1.l = (sign ? SIGNBIT : 0) | __INFINITY; + else if (exp1 < 0) + fl1.l = 0; + else + fl1.l = PACK (sign ? SIGNBIT : 0 , exp1, mant1); return (fl1.f); } + +#endif