summaryrefslogtreecommitdiff
path: root/linuxthreads/sysdeps/i386/pt-machine.h
diff options
context:
space:
mode:
Diffstat (limited to 'linuxthreads/sysdeps/i386/pt-machine.h')
-rw-r--r--linuxthreads/sysdeps/i386/pt-machine.h108
1 files changed, 108 insertions, 0 deletions
diff --git a/linuxthreads/sysdeps/i386/pt-machine.h b/linuxthreads/sysdeps/i386/pt-machine.h
new file mode 100644
index 0000000000..0df096d152
--- /dev/null
+++ b/linuxthreads/sysdeps/i386/pt-machine.h
@@ -0,0 +1,108 @@
+/* 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. */
+
+#ifndef _PT_MACHINE_H
+#define _PT_MACHINE_H 1
+
+#ifndef __ASSEMBLER__
+#ifndef PT_EI
+# define PT_EI extern inline __attribute__ ((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)
+{
+ int res;
+ __asm__ __volatile__ ("pushfl; popl %0" : "=r" (res) : );
+ return res;
+}
+
+
+PT_EI void
+set_eflags (int newflags)
+{
+ __asm__ __volatile__ ("pushl %0; popfl" : : "r" (newflags) : "cc");
+}
+
+
+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 */