diff options
Diffstat (limited to 'device/lib/_fsadd.c')
| -rw-r--r-- | device/lib/_fsadd.c | 252 |
1 files changed, 252 insertions, 0 deletions
diff --git a/device/lib/_fsadd.c b/device/lib/_fsadd.c new file mode 100644 index 0000000..d3ebe24 --- /dev/null +++ b/device/lib/_fsadd.c @@ -0,0 +1,252 @@ +/*------------------------------------------------------------------------- + _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 |