libpayload: Add faster, architecture specific versions of memset and memcpy.

Change-Id: I0f3a82de860fd3afa10a557b37fb90fe6b06ae90
Signed-off-by: Gabe Black <gabeblack@google.com>
Reviewed-on: http://review.coreboot.org/1726
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>
Tested-by: build bot (Jenkins)

payloads/libpayload/arch/i386/Makefile.inc

@@ -31,6 +31,7 @@ head.o-y += head.S
 libc-y += main.c sysinfo.c
 libc-y += timer.c coreboot.c util.S
 libc-y += exec.S virtual.c
+libc-y += string.c
 
 # Multiboot support is configurable
 libc-$(CONFIG_MULTIBOOT) += multiboot.c

payloads/libpayload/arch/i386/string.c

@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) 1991,1992,1993,1997,1998,2003, 2005 Free Software Foundation, Inc.
+ * This file is part of the GNU C Library.
+ * Copyright (c) 2011 The Chromium OS Authors.
+ *
+ * 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 <stdint.h>
+
+#include "string.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;
+}
+
+void *memcpy(void *dest, const void *src, size_t n)
+{
+	unsigned long d0, d1, d2;
+
+	asm volatile(
+		"rep ; movsl\n\t"
+		"movl %4,%%ecx\n\t"
+		"rep ; movsb\n\t"
+		: "=&c" (d0), "=&D" (d1), "=&S" (d2)
+		: "0" (n >> 2), "g" (n & 3), "1" (dest), "2" (src)
+		: "memory"
+	);
+
+	return dest;
+}