[PATCH] powerpc/math-emu: Use kernel generic math-emu code

[Kumar Gala]

On Sep 23, 2008, at 11:28 PM, Liu Yu-B13201 wrote:

>>
>> diff --git a/arch/powerpc/include/asm/sfp-machine.h
>> b/arch/powerpc/include/asm/sfp-machine.h
>> new file mode 100644
>> index 0000000..ced34f1
>> --- /dev/null
>> +++ b/arch/powerpc/include/asm/sfp-machine.h
>> @@ -0,0 +1,353 @@
>> +/* Machine-dependent software floating-point definitions.
>> PPC version.
>> +   Copyright (C) 1997 Free Software Foundation, Inc.
>> +   This file is part of the GNU C Library.
>> +
>> +   The GNU C Library 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.
>> +
>> +   The GNU C 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
>> +   Library General Public License for more details.
>> +
>> +   You should have received a copy of the GNU Library General Public
>> +   License along with the GNU C Library; see the file
>> COPYING.LIB.  If
>> +   not, write to the Free Software Foundation, Inc.,
>> +   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
>> +
>> +   Actually, this is a PPC (32bit) version, written based on the
>> +   i386, sparc, and sparc64 versions, by me,
>> +   Peter Maydell (pmaydell at chiark.greenend.org.uk).
>> +   Comments are by and large also mine, although they may be
>> inaccurate.
>> +
>> +   In picking out asm fragments I've gone with the lowest common
>> +   denominator, which also happens to be the hardware I have :->
>> +   That is, a SPARC without hardware multiply and divide.
>> + */
>> +
>> +/* basic word size definitions */
>> +#define _FP_W_TYPE_SIZE		32
>> +#define _FP_W_TYPE		unsigned long
>> +#define _FP_WS_TYPE		signed long
>> +#define _FP_I_TYPE		long
>> +
>> +#define __ll_B			((UWtype) 1 <<
>> (W_TYPE_SIZE / 2))
>> +#define __ll_lowpart(t)		((UWtype) (t) & (__ll_B - 1))
>> +#define __ll_highpart(t)	((UWtype) (t) >> (W_TYPE_SIZE / 2))
>> +
>> +/* You can optionally code some things like addition in asm. For
>> + * example, i386 defines __FP_FRAC_ADD_2 as asm. If you don't
>> + * then you get a fragment of C code [if you change an #ifdef 0
>> + * in op-2.h] or a call to add_ssaaaa (see below).
>> + * Good places to look for asm fragments to use are gcc and glibc.
>> + * gcc's longlong.h is useful.
>> + */
>> +
>> +/* We need to know how to multiply and divide. If the host word size
>> + * is >= 2*fracbits you can use FP_MUL_MEAT_n_imm(t,R,X,Y) which
>> + * codes the multiply with whatever gcc does to 'a * b'.
>> + * _FP_MUL_MEAT_n_wide(t,R,X,Y,f) is used when you have an asm
>> + * function that can multiply two 1W values and get a 2W result.
>> + * Otherwise you're stuck with _FP_MUL_MEAT_n_hard(t,R,X,Y) which
>> + * does bitshifting to avoid overflow.
>> + * For division there is FP_DIV_MEAT_n_imm(t,R,X,Y,f) for word size
>> + * >= 2*fracbits, where f is either _FP_DIV_HELP_imm or
>> + * _FP_DIV_HELP_ldiv (see op-1.h).
>> + * _FP_DIV_MEAT_udiv() is if you have asm to do 2W/1W => (1W, 1W).
>> + * [GCC and glibc have longlong.h which has the asm macro udiv_qrnnd
>> + * to do this.]
>> + * In general, 'n' is the number of words required to hold the type,
>> + * and 't' is either S, D or Q for single/double/quad.
>> + *           -- PMM
>> + */
>> +/* Example: SPARC64:
>> + * #define _FP_MUL_MEAT_S(R,X,Y)	_FP_MUL_MEAT_1_imm(S,R,X,Y)
>> + * #define _FP_MUL_MEAT_D(R,X,Y)	
>> _FP_MUL_MEAT_1_wide(D,R,X,Y,umul_ppmm)
>> + * #define _FP_MUL_MEAT_Q(R,X,Y)	
>> _FP_MUL_MEAT_2_wide(Q,R,X,Y,umul_ppmm)
>> + *
>> + * #define _FP_DIV_MEAT_S(R,X,Y)	
>> _FP_DIV_MEAT_1_imm(S,R,X,Y,_FP_DIV_HELP_imm)
>> + * #define _FP_DIV_MEAT_D(R,X,Y)	_FP_DIV_MEAT_1_udiv(D,R,X,Y)
>> + * #define _FP_DIV_MEAT_Q(R,X,Y)	_FP_DIV_MEAT_2_udiv_64(Q,R,X,Y)
>> + *
>> + * Example: i386:
>> + * #define _FP_MUL_MEAT_S(R,X,Y)
>> _FP_MUL_MEAT_1_wide(S,R,X,Y,_i386_mul_32_64)
>> + * #define _FP_MUL_MEAT_D(R,X,Y)
>> _FP_MUL_MEAT_2_wide(D,R,X,Y,_i386_mul_32_64)
>> + *
>> + * #define _FP_DIV_MEAT_S(R,X,Y)
>> _FP_DIV_MEAT_1_udiv(S,R,X,Y,_i386_div_64_32)
>> + * #define _FP_DIV_MEAT_D(R,X,Y)   _FP_DIV_MEAT_2_udiv_64(D,R,X,Y)
>> + */
>> +
>> +#define _FP_MUL_MEAT_S(R,X,Y)
>> _FP_MUL_MEAT_1_wide(_FP_WFRACBITS_S,R,X,Y,umul_ppmm)
>> +#define _FP_MUL_MEAT_D(R,X,Y)
>> _FP_MUL_MEAT_2_wide(_FP_WFRACBITS_D,R,X,Y,umul_ppmm)
>> +
>> +#define _FP_DIV_MEAT_S(R,X,Y)	_FP_DIV_MEAT_1_udiv(S,R,X,Y)
>
> It seems _FP_DIV_MEAT_S() should be defined to
> _FP_DIV_MEAT_1_udiv_norm().
> I can't remember very clear, but it seems single point float need to  
> be
> normalized before calling udiv_qrnnd.

For now I'm leaving as it was in the old code.  We can submit fixes on  
top of this patch.

- k