diff options
Diffstat (limited to 'libc/sysdeps/linux/i386/fpu_control.h')
| -rw-r--r-- | libc/sysdeps/linux/i386/fpu_control.h | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/libc/sysdeps/linux/i386/fpu_control.h b/libc/sysdeps/linux/i386/fpu_control.h index ed9bf388a..c6cb005d7 100644 --- a/libc/sysdeps/linux/i386/fpu_control.h +++ b/libc/sysdeps/linux/i386/fpu_control.h @@ -1,5 +1,5 @@ /* FPU control word bits. i387 version. - Copyright (C) 1993,1995,1996,1997,1998,2000,2001 Free Software Foundation, Inc. + Copyright (C) 1993,1995-1998,2000,2001,2003 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Olaf Flebbe. @@ -88,11 +88,17 @@ /* Type of the control word. */ typedef unsigned int fpu_control_t __attribute__ ((__mode__ (__HI__))); -/* Macros for accessing the hardware control word. */ -#define _FPU_GETCW(cw) __asm__ ("fnstcw %0" : "=m" (*&cw)) -#define _FPU_SETCW(cw) __asm__ ("fldcw %0" : : "m" (*&cw)) +/* Macros for accessing the hardware control word. + Note that the use of these macros is no sufficient anymore with + recent hardware. Some floating point operations are executed in + the SSE/SSE2 engines which have their own control and status register. */ +#define _FPU_GETCW(cw) __asm__ __volatile__ ("fnstcw %0" : "=m" (*&cw)) +#define _FPU_SETCW(cw) __asm__ __volatile__ ("fldcw %0" : : "m" (*&cw)) + +#if 0 /* Default control word set at startup. */ extern fpu_control_t __fpu_control; +#endif #endif /* fpu_control.h */ |