gcc 3.3-2 complains with arch/i386/meth-emu/poly.h

Marco Bagni (m.bagni@marcobagni.com)
Thu, 05 Jun 2003 16:00:34 +0200


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Dear Sirs,

I have found a minor bug in the file "arch/i386/meth-emu/poly.h".

It seems that gcc does not allow anymore the "implicit" continuation
of a string in the next line and complains during the compilation of the
file "arch/i386/meth-emu/poly.h" in the execution of the asm directive
of the functions "add_Xsig_Xsig" and "add_two_Xsig". I have added my
"changes" which I submit to your attention.

I know that nobody uses this math-emulation code anymore, but if it has
to be in Kernel, it must be possible to compile it without problems.

Regards

Marco Bagni

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filename="poly.h"

/*---------------------------------------------------------------------------+
| poly.h |
| |
| Header file for the FPU-emu poly*.c source files. |
| |
| Copyright (C) 1994,1999 |
| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, |
| Australia. E-mail billm@melbpc.org.au |
| |
| Declarations and definitions for functions operating on Xsig (12-byte |
| extended-significand) quantities. |
| |
+---------------------------------------------------------------------------*/

#ifndef _POLY_H
#define _POLY_H

/* This 12-byte structure is used to improve the accuracy of computation
of transcendental functions.
Intended to be used to get results better than 8-byte computation
allows. 9-byte would probably be sufficient.
*/
typedef struct {
unsigned long lsw;
unsigned long midw;
unsigned long msw;
} Xsig;

asmlinkage void mul64(unsigned long long const *a, unsigned long long const *b,
unsigned long long *result);
asmlinkage void polynomial_Xsig(Xsig *, const unsigned long long *x,
const unsigned long long terms[], const int n);

asmlinkage void mul32_Xsig(Xsig *, const unsigned long mult);
asmlinkage void mul64_Xsig(Xsig *, const unsigned long long *mult);
asmlinkage void mul_Xsig_Xsig(Xsig *dest, const Xsig *mult);

asmlinkage void shr_Xsig(Xsig *, const int n);
asmlinkage int round_Xsig(Xsig *);
asmlinkage int norm_Xsig(Xsig *);
asmlinkage void div_Xsig(Xsig *x1, const Xsig *x2, const Xsig *dest);

/* Macro to extract the most significant 32 bits from a long long */
#define LL_MSW(x) (((unsigned long *)&x)[1])

/* Macro to initialize an Xsig struct */
#define MK_XSIG(a,b,c) { c, b, a }

/* Macro to access the 8 ms bytes of an Xsig as a long long */
#define XSIG_LL(x) (*(unsigned long long *)&x.midw)

/*
Need to run gcc with optimizations on to get these to
actually be in-line.
*/

/* Multiply two fixed-point 32 bit numbers, producing a 32 bit result.
The answer is the ms word of the product. */
/* Some versions of gcc make it difficult to stop eax from being clobbered.
Merely specifying that it is used doesn't work...
*/
static inline unsigned long mul_32_32(const unsigned long arg1,
const unsigned long arg2)
{
int retval;
asm volatile ("mull %2; movl %%edx,%%eax" \
:"=a" (retval) \
:"0" (arg1), "g" (arg2) \
:"dx");
return retval;
}

/* Changed by Marco Bagni */
/* Add the 12 byte Xsig x2 to Xsig dest, with no checks for overflow. */
static inline void add_Xsig_Xsig(Xsig *dest, const Xsig *x2)
{
asm volatile ("movl %1,%%edi; movl %2,%%esi; "
"movl (%%esi),%%eax; addl %%eax,(%%edi); "
"movl 4(%%esi),%%eax; adcl %%eax,4(%%edi); "
"movl 8(%%esi),%%eax; adcl %%eax,8(%%edi);"
:"=g" (*dest):"g" (dest), "g" (x2)
:"ax","si","di");
}

/* Changed by Marco Bagni */
/* Add the 12 byte Xsig x2 to Xsig dest, adjust exp if overflow occurs. */
/* Note: the constraints in the asm statement didn't always work properly
with gcc 2.5.8. Changing from using edi to using ecx got around the
problem, but keep fingers crossed! */
static inline void add_two_Xsig(Xsig *dest, const Xsig *x2, long int *exp)
{
asm volatile ("movl %2,%%ecx; movl %3,%%esi; "
"movl (%%esi),%%eax; addl %%eax,(%%ecx); "
"movl 4(%%esi),%%eax; adcl %%eax,4(%%ecx); "
"movl 8(%%esi),%%eax; adcl %%eax,8(%%ecx); "
"jnc 0f; "
"rcrl 8(%%ecx); rcrl 4(%%ecx); rcrl (%%ecx); "
"movl %4,%%ecx; incl (%%ecx); "
"movl $1,%%eax; jmp 1f; "
"0: xorl %%eax,%%eax; "
"1:"
:"=g" (*exp), "=g" (*dest)
:"g" (dest), "g" (x2), "g" (exp)
:"cx","si","ax");
}

/* Negate (subtract from 1.0) the 12 byte Xsig */
/* This is faster in a loop on my 386 than using the "neg" instruction. */
static inline void negate_Xsig(Xsig *x)
{
asm volatile("movl %1,%%esi; "
"xorl %%ecx,%%ecx; "
"movl %%ecx,%%eax; subl (%%esi),%%eax; movl %%eax,(%%esi); "
"movl %%ecx,%%eax; sbbl 4(%%esi),%%eax; movl %%eax,4(%%esi); "
"movl %%ecx,%%eax; sbbl 8(%%esi),%%eax; movl %%eax,8(%%esi); "
:"=g" (*x):"g" (x):"si","ax","cx");
}

#endif /* _POLY_H */

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