1 files changed, 61 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/alpha/syscall.S b/sysdeps/unix/sysv/linux/alpha/syscall.S
new file mode 100644
index 0000000000..54a8484c58
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/alpha/syscall.S
@@ -0,0 +1,61 @@
+/* Copyright (C) 1996 Free Software Foundation, Inc.
+   Contributed by David Mosberger (davidm@azstarnet.com).
+
+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., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+#include <sysdep.h>
+
+/*
+ * This is for COMPATIBILITY with Linux/x86 only.  Linux/Alpha system
+ * calls return an error indication in a3.  This allows to return
+ * arbitrary 64bit values in v0 (because negative values are not
+ * mistaken as error numbers).  However, C allows to return only one
+ * value so the interface below folds the error indication passed in
+ * a3 back into v0: it sets v0 to -errno if an error occurs.  Thus,
+ * no negative 64bit numbers can be returned.  To avoid this problem,
+ * use assembly stubs wherever possible/convenient.
+ *
+ * Usage:
+ *
+ * long	syscall(syscall_number, arg1, arg2, arg3, arg4, arg5)
+ *
+ * syscall_number = the index of the system call we're invoking
+ * arg1-arg5 = up to 5 integer arguments to the system call
+ *
+ * We need to do some arg shifting: the kernel expects the
+ * syscall number in v0 and the first five args in a0-a4.
+ *
+ */
+
+
+1:	br	gp,2f
+2:	ldgp	gp,0(gp)
+	jmp	zero,syscall_error
+
+
+ENTRY (__syscall)
+	bis	a0,a0,v0	# Syscall number -> v0
+	bis	a1,a1,a0	# arg1-arg5 -> a0-a4
+	bis	a2,a2,a1
+	bis	a3,a3,a2
+	bis	a4,a4,a3
+	bis	a5,a5,a4
+
+	call_pal PAL_callsys	# Invoke system call
+	bne	a3,1b
+	ret
+
+weak_alias(__syscall, syscall)