aboutsummaryrefslogtreecommitdiffstats
path: root/arch/openrisc/lib
diff options
context:
space:
mode:
authorOlof Kindgren <olof.kindgren@gmail.com>2015-02-06 13:41:51 +0100
committerStafford Horne <shorne@gmail.com>2017-02-25 04:14:35 +0900
commitd857a1e253498feb231173218df26f5562c70f09 (patch)
tree4d7c67c6d2c648d52a83f68e5ebaa3882c791073 /arch/openrisc/lib
parente29d11c6991d078bf2011f25dc8c19a2f38c4c8e (diff)
openrisc: Add optimized memset
This adds a hand-optimized assembler version of memset and sets __HAVE_ARCH_MEMSET to use this version instead of the generic C routine Signed-off-by: Olof Kindgren <olof.kindgren@gmail.com> Signed-off-by: Stafford Horne <shorne@gmail.com>
Diffstat (limited to 'arch/openrisc/lib')
-rw-r--r--arch/openrisc/lib/Makefile2
-rw-r--r--arch/openrisc/lib/memset.S98
2 files changed, 99 insertions, 1 deletions
diff --git a/arch/openrisc/lib/Makefile b/arch/openrisc/lib/Makefile
index 966f65dbc6f0..67c583e0617f 100644
--- a/arch/openrisc/lib/Makefile
+++ b/arch/openrisc/lib/Makefile
@@ -2,4 +2,4 @@
# Makefile for or32 specific library files..
#
-obj-y = string.o delay.o
+obj-y = memset.o string.o delay.o
diff --git a/arch/openrisc/lib/memset.S b/arch/openrisc/lib/memset.S
new file mode 100644
index 000000000000..92cc2eac26fa
--- /dev/null
+++ b/arch/openrisc/lib/memset.S
@@ -0,0 +1,98 @@
+/*
+ * OpenRISC memset.S
+ *
+ * Hand-optimized assembler version of memset for OpenRISC.
+ * Algorithm inspired by several other arch-specific memset routines
+ * in the kernel tree
+ *
+ * Copyright (C) 2015 Olof Kindgren <olof.kindgren@gmail.com>
+ *
+ * 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.
+ */
+
+ .global memset
+ .type memset, @function
+memset:
+ /* arguments:
+ * r3 = *s
+ * r4 = c
+ * r5 = n
+ * r13, r15, r17, r19 used as temp regs
+ */
+
+ /* Exit if n == 0 */
+ l.sfeqi r5, 0
+ l.bf 4f
+
+ /* Truncate c to char */
+ l.andi r13, r4, 0xff
+
+ /* Skip word extension if c is 0 */
+ l.sfeqi r13, 0
+ l.bf 1f
+ /* Check for at least two whole words (8 bytes) */
+ l.sfleui r5, 7
+
+ /* Extend char c to 32-bit word cccc in r13 */
+ l.slli r15, r13, 16 // r13 = 000c, r15 = 0c00
+ l.or r13, r13, r15 // r13 = 0c0c, r15 = 0c00
+ l.slli r15, r13, 8 // r13 = 0c0c, r15 = c0c0
+ l.or r13, r13, r15 // r13 = cccc, r15 = c0c0
+
+1: l.addi r19, r3, 0 // Set r19 = src
+ /* Jump to byte copy loop if less than two words */
+ l.bf 3f
+ l.or r17, r5, r0 // Set r17 = n
+
+ /* Mask out two LSBs to check alignment */
+ l.andi r15, r3, 0x3
+
+ /* lsb == 00, jump to word copy loop */
+ l.sfeqi r15, 0
+ l.bf 2f
+ l.addi r19, r3, 0 // Set r19 = src
+
+ /* lsb == 01,10 or 11 */
+ l.sb 0(r3), r13 // *src = c
+ l.addi r17, r17, -1 // Decrease n
+
+ l.sfeqi r15, 3
+ l.bf 2f
+ l.addi r19, r3, 1 // src += 1
+
+ /* lsb == 01 or 10 */
+ l.sb 1(r3), r13 // *(src+1) = c
+ l.addi r17, r17, -1 // Decrease n
+
+ l.sfeqi r15, 2
+ l.bf 2f
+ l.addi r19, r3, 2 // src += 2
+
+ /* lsb == 01 */
+ l.sb 2(r3), r13 // *(src+2) = c
+ l.addi r17, r17, -1 // Decrease n
+ l.addi r19, r3, 3 // src += 3
+
+ /* Word copy loop */
+2: l.sw 0(r19), r13 // *src = cccc
+ l.addi r17, r17, -4 // Decrease n
+ l.sfgeui r17, 4
+ l.bf 2b
+ l.addi r19, r19, 4 // Increase src
+
+ /* When n > 0, copy the remaining bytes, otherwise jump to exit */
+ l.sfeqi r17, 0
+ l.bf 4f
+
+ /* Byte copy loop */
+3: l.addi r17, r17, -1 // Decrease n
+ l.sb 0(r19), r13 // *src = cccc
+ l.sfnei r17, 0
+ l.bf 3b
+ l.addi r19, r19, 1 // Increase src
+
+4: l.jr r9
+ l.ori r11, r3, 0

Privacy Policy