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| /* SPDX-License-Identifier: GPL-2.0-or-later */
| /*
| * 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>
| */
|
| .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
|
|
