Rewritten.

sysdeps/unix/sysv/sysv4/linux/i386/sysdep.h

@@ -0,0 +1,86 @@
+/* Copyright (C) 1992, 1993, 1995 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+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.  */
+
+/* In the Linux/ELF world, C symbols are asm symbols.  */
+#define NO_UNDERSCORES
+
+/* There is some commonality.  */
+#include <sysdeps/unix/i386/sysdep.h>
+
+#ifdef ASSEMBLER
+
+/* Linux uses a negative return value to indicate syscall errors, unlike
+   most Unices, which use the condition codes' carry flag.  */
+#undef	PSEUDO
+#define	PSEUDO(name, syscall_name, args)				      \
+  .text;								      \
+  .globl __syscall_error;						      \
+  ENTRY (name)								      \
+    movl $SYS_##syscall_name, %eax;					      \
+    DO_CALL (args)							      \
+    testl %eax, %eax;							      \
+    jl JUMPTARGET(__syscall_error)
+
+
+/* Linux takes system call arguments in registers:
+
+	syscall number	%eax	     call-clobbered
+	arg 1		%ebx	     call-saved
+	arg 2		%ecx	     call-clobbered
+	arg 3		%edx	     call-clobbered
+	arg 4		%esi	     call-saved
+	arg 5		%edi	     call-saved
+
+   The stack layout upon entering the function is:
+
+	24(%esp)	Arg# 5
+	20(%esp)	Arg# 4
+	16(%esp)	Arg# 3
+	12(%esp)	Arg# 2
+	 8(%esp)	Arg# 1
+	 4(%esp)	Return address
+	  (%esp)
+
+   (Of course a function with e.g. 3 argumentS does not have entries for
+   arguments 4 and 5.)
+
+   We put the arguments into registers from the stack, and save the
+   call-saved registers, by using the 386 `xchg' instruction to swap the
+   values in both directions.  */
+
+#undef	DO_CALL
+#define DO_CALL(args)					      		      \
+    DOARGS_##args							      \
+    int $0x80;								      \
+    UNDOARGS_##args							      \
+
+#define	DOARGS_0	/* No arguments to frob.  */
+#define	UNDOARGS_0	/* No arguments to unfrob.  */
+#define	DOARGS_1	xchg 8(%esp), %ebx; DOARGS_0 /* Save %ebx on stack.  */
+#define	UNDOARGS_1	xchg 8(%esp), %ebx; UNDOARGS_0 /* Restore %ebx */
+#define	DOARGS_2	movel 12(%esp), %ecx; DOARGS_1
+#define	UNDOARGS_2	UNDOARGS_1 /* %ecx is clobbered.  */
+#define	DOARGS_3	movel 16(%esp), %edx; DOARGS_2
+#define	UNDOARGS_3	UNDOARGS_2 /* %edx is clobbered.  */
+#define	DOARGS_4	xchg 20(%esp), %esi; DOARGS_3 /* Save %esi on stack. */
+#define	UNDOARGS_4	xchg 20(%esp), %esi; UNDOARGS_3	/* Restore %esi.  */
+#define	DOARGS_5	xchg 24(%esp), %edi; DOARGS_3 /* Save %edi on stack. */
+#define	UNDOARGS_5	xchg 24(%esp), %edi; UNDOARGS_3	/* Restore %edi.  */
+
+
+#endif	/* ASSEMBLER */