From 1afe51af83ad0beb3f0ace1085524b327ecff7c6 Mon Sep 17 00:00:00 2001
From: Stefan Reinauer <reinauer@chromium.org>
Date: Wed, 26 Oct 2011 22:11:52 +0000
Subject: [PATCH] Add native memset() function on x86

Change-Id: Ia118ebe0a4b59bdcefd78895141a365170f6aed2
Signed-off-by: Stefan Reinauer <reinauer@google.com>
Reviewed-on: http://review.coreboot.org/737
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Tested-by: build bot (Jenkins)
---
 src/arch/x86/Kconfig          |  4 ++
 src/arch/x86/lib/Makefile.inc |  2 +
 src/arch/x86/lib/memset.c     | 85 +++++++++++++++++++++++++++++++++++
 src/lib/Makefile.inc          |  4 ++
 4 files changed, 95 insertions(+)
 create mode 100644 src/arch/x86/lib/memset.c

diff --git a/src/arch/x86/Kconfig b/src/arch/x86/Kconfig
index 5ee7c4ac7..4ca49cbaf 100644
--- a/src/arch/x86/Kconfig
+++ b/src/arch/x86/Kconfig
@@ -76,6 +76,10 @@ config CMOS_DEFAULT_FILE
 config BOOTBLOCK_SOUTHBRIDGE_INIT
 	string
 
+config HAVE_ARCH_MEMSET
+	bool
+	default y
+
 config HAVE_ARCH_MEMCPY
 	bool
 	default y
diff --git a/src/arch/x86/lib/Makefile.inc b/src/arch/x86/lib/Makefile.inc
index f99e429ee..3f4dc9556 100644
--- a/src/arch/x86/lib/Makefile.inc
+++ b/src/arch/x86/lib/Makefile.inc
@@ -8,10 +8,12 @@ ramstage-$(CONFIG_MMCONF_SUPPORT) += pci_ops_mmconf.c
 ramstage-y += pci_ops_auto.c
 ramstage-y += exception.c
 ramstage-$(CONFIG_IOAPIC) += ioapic.c
+ramstage-y += memset.c
 ramstage-y += memcpy.c
 
 romstage-y += romstage_console.c
 romstage-y += cbfs_and_run.c
+romstage-y += memset.c
 romstage-y += memcpy.c
 
 smm-y += memcpy.c
diff --git a/src/arch/x86/lib/memset.c b/src/arch/x86/lib/memset.c
new file mode 100644
index 000000000..7c8129a3f
--- /dev/null
+++ b/src/arch/x86/lib/memset.c
@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 1991,1992,1993,1997,1998,2003, 2005 Free Software Foundation, Inc.
+ * This file is part of the GNU C Library.
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+/* From glibc-2.14, sysdeps/i386/memset.c */
+
+#include <string.h>
+#include <stdint.h>
+
+typedef uint32_t op_t;
+
+void *memset(void *dstpp, int c, size_t len)
+{
+	int d0;
+	unsigned long int dstp = (unsigned long int) dstpp;
+
+	/* This explicit register allocation improves code very much indeed. */
+	register op_t x asm("ax");
+
+	x = (unsigned char) c;
+
+	/* Clear the direction flag, so filling will move forward.  */
+	asm volatile("cld");
+
+	/* This threshold value is optimal.  */
+	if (len >= 12) {
+		/* Fill X with four copies of the char we want to fill with. */
+		x |= (x << 8);
+		x |= (x << 16);
+
+		/* Adjust LEN for the bytes handled in the first loop.  */
+		len -= (-dstp) % sizeof(op_t);
+
+		/*
+		 * There are at least some bytes to set. No need to test for
+		 * LEN == 0 in this alignment loop.
+		 */
+
+		/* Fill bytes until DSTP is aligned on a longword boundary. */
+		asm volatile(
+			"rep\n"
+			"stosb" /* %0, %2, %3 */ :
+			"=D" (dstp), "=c" (d0) :
+			"0" (dstp), "1" ((-dstp) % sizeof(op_t)), "a" (x) :
+			"memory");
+
+		/* Fill longwords.  */
+		asm volatile(
+			"rep\n"
+			"stosl" /* %0, %2, %3 */ :
+			"=D" (dstp), "=c" (d0) :
+			"0" (dstp), "1" (len / sizeof(op_t)), "a" (x) :
+			"memory");
+		len %= sizeof(op_t);
+	}
+
+	/* Write the last few bytes. */
+	asm volatile(
+		"rep\n"
+		"stosb" /* %0, %2, %3 */ :
+		"=D" (dstp), "=c" (d0) :
+		"0" (dstp), "1" (len), "a" (x) :
+		"memory");
+
+	return dstpp;
+}
diff --git a/src/lib/Makefile.inc b/src/lib/Makefile.inc
index 61b6451d0..8ce72b2a9 100644
--- a/src/lib/Makefile.inc
+++ b/src/lib/Makefile.inc
@@ -1,6 +1,8 @@
 
 
+ifneq ($(CONFIG_HAVE_ARCH_MEMSET),y)
 romstage-y += memset.c
+endif
 romstage-y += memchr.c
 ifneq ($(CONFIG_HAVE_ARCH_MEMCPY),y)
 romstage-y += memcpy.c
@@ -19,7 +21,9 @@ romstage-$(CONFIG_CONSOLE_NE2K) += compute_ip_checksum.c
 romstage-$(CONFIG_USBDEBUG) += usbdebug.c
 romstage-$(CONFIG_COLLECT_TIMESTAMPS) += timestamp.c
 
+ifneq ($(CONFIG_HAVE_ARCH_MEMSET),y)
 ramstage-y += memset.c
+endif
 ramstage-y += memchr.c
 ifneq ($(CONFIG_HAVE_ARCH_MEMCPY),y)
 ramstage-y += memcpy.c
-- 
2.25.1