/* Machine-dependent pthreads configuration and inline functions. i386 version. Copyright (C) 1996-2001, 2002, 2003 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Richard Henderson <rth@tamu.edu>. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details. You should have received a copy of the GNU Lesser 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. */ #if defined __pentiumpro__ || defined __pentium4__ || defined __athlon__ || \ defined __k8__ # include "i686/pt-machine.h" #else #ifndef _PT_MACHINE_H #define _PT_MACHINE_H 1 #ifndef __ASSEMBLER__ #ifndef PT_EI # define PT_EI __extern_always_inline #endif /* extern long int testandset (int *spinlock); extern int __compare_and_swap (long int *p, long int oldval, long int newval); */ /* Get some notion of the current stack. Need not be exactly the top of the stack, just something somewhere in the current frame. */ #define CURRENT_STACK_FRAME __builtin_frame_address (0) /* Spinlock implementation; required. */ PT_EI long int testandset (int *spinlock) { long int ret; __asm__ __volatile__( "xchgl %0, %1" : "=r"(ret), "=m"(*spinlock) : "0"(1), "m"(*spinlock) : "memory"); return ret; } /* Compare-and-swap for semaphores. Available on the 486 and above, but not on the 386. We test dynamically whether it's available or not. */ #define HAS_COMPARE_AND_SWAP #define TEST_FOR_COMPARE_AND_SWAP PT_EI int __compare_and_swap (long int *p, long int oldval, long int newval) { char ret; long int readval; __asm__ __volatile__ ("lock; cmpxchgl %3, %1; sete %0" : "=q" (ret), "=m" (*p), "=a" (readval) : "r" (newval), "m" (*p), "a" (oldval) : "memory"); return ret; } PT_EI int get_eflags (void); PT_EI int get_eflags (void) { int res; __asm__ __volatile__ ("pushfl; popl %0" : "=r" (res) : ); return res; } PT_EI void set_eflags (int newflags); PT_EI void set_eflags (int newflags) { __asm__ __volatile__ ("pushl %0; popfl" : : "r" (newflags) : "cc"); } PT_EI int compare_and_swap_is_available (void); PT_EI int compare_and_swap_is_available (void) { int oldflags = get_eflags (); int changed; /* Flip AC bit in EFLAGS. */ set_eflags (oldflags ^ 0x40000); /* See if bit changed. */ changed = (get_eflags () ^ oldflags) & 0x40000; /* Restore EFLAGS. */ set_eflags (oldflags); /* If the AC flag did not change, it's a 386 and it lacks cmpxchg. Otherwise, it's a 486 or above and it has cmpxchg. */ return changed != 0; } #endif /* __ASSEMBLER__ */ #endif /* pt-machine.h */ #endif