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authorGabe Black <gabeblack@chromium.org>2011-11-14 14:47:18 +0000
committerGraeme Russ <graeme.russ@gmail.com>2011-11-29 21:31:17 +1100
commitdbaef6ef33912a863f9fb550857028fb96e42c59 (patch)
tree255343e0720426f7e7cbbb678bc93af506aff74c /arch/x86
parent60a9b6bfddbe1e3ae280fe5422ccd283bc31a591 (diff)
downloadu-boot-linaro-stable-dbaef6ef33912a863f9fb550857028fb96e42c59.tar.gz
x86: Import the glibc memset implementation
The new implementation is about twice as fast as the old. This is from glibc-2.14, sysdeps/i386/memset.c. Signed-off-by: Gabe Black <gabeblack@chromium.org>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/include/asm/string.h2
-rw-r--r--arch/x86/lib/Makefile1
-rw-r--r--arch/x86/lib/string.c87
3 files changed, 89 insertions, 1 deletions
diff --git a/arch/x86/include/asm/string.h b/arch/x86/include/asm/string.h
index 3643a79fd..3aa6c1131 100644
--- a/arch/x86/include/asm/string.h
+++ b/arch/x86/include/asm/string.h
@@ -23,7 +23,7 @@ extern void * memmove(void *, const void *, __kernel_size_t);
#undef __HAVE_ARCH_MEMCHR
extern void * memchr(const void *, int, __kernel_size_t);
-#undef __HAVE_ARCH_MEMSET
+#define __HAVE_ARCH_MEMSET
extern void * memset(void *, int, __kernel_size_t);
#undef __HAVE_ARCH_MEMZERO
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index eb5fa1039..90f328333 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -38,6 +38,7 @@ COBJS-$(CONFIG_SYS_GENERIC_TIMER) += pcat_timer.o
COBJS-$(CONFIG_PCI) += pci.o
COBJS-$(CONFIG_PCI) += pci_type1.o
COBJS-$(CONFIG_SYS_X86_REALMODE) += realmode.o
+COBJS-y += string.o
COBJS-$(CONFIG_SYS_X86_ISR_TIMER) += timer.o
COBJS-$(CONFIG_VIDEO) += video_bios.o
COBJS-$(CONFIG_VIDEO) += video.o
diff --git a/arch/x86/lib/string.c b/arch/x86/lib/string.c
new file mode 100644
index 000000000..f2ea7e4e3
--- /dev/null
+++ b/arch/x86/lib/string.c
@@ -0,0 +1,87 @@
+/*
+ * 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 <compiler.h>
+#include <asm/string.h>
+#include <linux/types.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;
+}