solve the bounce buffer problem!

1 files changed, 58 insertions, 0 deletions

diff --git a/sys/arch/i386/stand/libsa/alloca.S b/sys/arch/i386/stand/libsa/alloca.S
new file mode 100644
index 00000000000..6e14bbd3bc6
--- /dev/null
+++ b/sys/arch/i386/stand/libsa/alloca.S
@@ -0,0 +1,58 @@
+/*-
+ * Copyright (c) 1990 The Regents of the University of California.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * William Jolitz.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <machine/asm.h>
+
+#if defined(LIBC_SCCS)
+	.text
+	.asciz "$OpenBSD: alloca.S,v 1.1 1997/04/30 18:10:06 mickey Exp $"
+#endif
+
+/* like alloc, but automatic automatic free in return */
+
+ENTRY(alloca)
+	popl	%edx		/*  pop return addr */
+	popl	%eax		/*  pop amount to allocate */
+	movl	%esp,%ecx
+	addl	$3,%eax		/*  round up to next word */
+	andl	$-4,%eax
+	subl	%eax,%esp
+	movl	%esp,%eax	/* base of newly allocated space */
+	pushl	8(%ecx)		/* copy possible saved registers */
+	pushl	4(%ecx)
+	pushl	0(%ecx)
+	pushl	%eax		/* dummy to pop at callsite */
+	jmp	%edx		/* "return" */