1*4882a593Smuzhiyun/* SPDX-License-Identifier: GPL-2.0-or-later */ 2*4882a593Smuzhiyun/* 3*4882a593Smuzhiyun * OpenRISC memset.S 4*4882a593Smuzhiyun * 5*4882a593Smuzhiyun * Hand-optimized assembler version of memset for OpenRISC. 6*4882a593Smuzhiyun * Algorithm inspired by several other arch-specific memset routines 7*4882a593Smuzhiyun * in the kernel tree 8*4882a593Smuzhiyun * 9*4882a593Smuzhiyun * Copyright (C) 2015 Olof Kindgren <olof.kindgren@gmail.com> 10*4882a593Smuzhiyun */ 11*4882a593Smuzhiyun 12*4882a593Smuzhiyun .global memset 13*4882a593Smuzhiyun .type memset, @function 14*4882a593Smuzhiyunmemset: 15*4882a593Smuzhiyun /* arguments: 16*4882a593Smuzhiyun * r3 = *s 17*4882a593Smuzhiyun * r4 = c 18*4882a593Smuzhiyun * r5 = n 19*4882a593Smuzhiyun * r13, r15, r17, r19 used as temp regs 20*4882a593Smuzhiyun */ 21*4882a593Smuzhiyun 22*4882a593Smuzhiyun /* Exit if n == 0 */ 23*4882a593Smuzhiyun l.sfeqi r5, 0 24*4882a593Smuzhiyun l.bf 4f 25*4882a593Smuzhiyun 26*4882a593Smuzhiyun /* Truncate c to char */ 27*4882a593Smuzhiyun l.andi r13, r4, 0xff 28*4882a593Smuzhiyun 29*4882a593Smuzhiyun /* Skip word extension if c is 0 */ 30*4882a593Smuzhiyun l.sfeqi r13, 0 31*4882a593Smuzhiyun l.bf 1f 32*4882a593Smuzhiyun /* Check for at least two whole words (8 bytes) */ 33*4882a593Smuzhiyun l.sfleui r5, 7 34*4882a593Smuzhiyun 35*4882a593Smuzhiyun /* Extend char c to 32-bit word cccc in r13 */ 36*4882a593Smuzhiyun l.slli r15, r13, 16 // r13 = 000c, r15 = 0c00 37*4882a593Smuzhiyun l.or r13, r13, r15 // r13 = 0c0c, r15 = 0c00 38*4882a593Smuzhiyun l.slli r15, r13, 8 // r13 = 0c0c, r15 = c0c0 39*4882a593Smuzhiyun l.or r13, r13, r15 // r13 = cccc, r15 = c0c0 40*4882a593Smuzhiyun 41*4882a593Smuzhiyun1: l.addi r19, r3, 0 // Set r19 = src 42*4882a593Smuzhiyun /* Jump to byte copy loop if less than two words */ 43*4882a593Smuzhiyun l.bf 3f 44*4882a593Smuzhiyun l.or r17, r5, r0 // Set r17 = n 45*4882a593Smuzhiyun 46*4882a593Smuzhiyun /* Mask out two LSBs to check alignment */ 47*4882a593Smuzhiyun l.andi r15, r3, 0x3 48*4882a593Smuzhiyun 49*4882a593Smuzhiyun /* lsb == 00, jump to word copy loop */ 50*4882a593Smuzhiyun l.sfeqi r15, 0 51*4882a593Smuzhiyun l.bf 2f 52*4882a593Smuzhiyun l.addi r19, r3, 0 // Set r19 = src 53*4882a593Smuzhiyun 54*4882a593Smuzhiyun /* lsb == 01,10 or 11 */ 55*4882a593Smuzhiyun l.sb 0(r3), r13 // *src = c 56*4882a593Smuzhiyun l.addi r17, r17, -1 // Decrease n 57*4882a593Smuzhiyun 58*4882a593Smuzhiyun l.sfeqi r15, 3 59*4882a593Smuzhiyun l.bf 2f 60*4882a593Smuzhiyun l.addi r19, r3, 1 // src += 1 61*4882a593Smuzhiyun 62*4882a593Smuzhiyun /* lsb == 01 or 10 */ 63*4882a593Smuzhiyun l.sb 1(r3), r13 // *(src+1) = c 64*4882a593Smuzhiyun l.addi r17, r17, -1 // Decrease n 65*4882a593Smuzhiyun 66*4882a593Smuzhiyun l.sfeqi r15, 2 67*4882a593Smuzhiyun l.bf 2f 68*4882a593Smuzhiyun l.addi r19, r3, 2 // src += 2 69*4882a593Smuzhiyun 70*4882a593Smuzhiyun /* lsb == 01 */ 71*4882a593Smuzhiyun l.sb 2(r3), r13 // *(src+2) = c 72*4882a593Smuzhiyun l.addi r17, r17, -1 // Decrease n 73*4882a593Smuzhiyun l.addi r19, r3, 3 // src += 3 74*4882a593Smuzhiyun 75*4882a593Smuzhiyun /* Word copy loop */ 76*4882a593Smuzhiyun2: l.sw 0(r19), r13 // *src = cccc 77*4882a593Smuzhiyun l.addi r17, r17, -4 // Decrease n 78*4882a593Smuzhiyun l.sfgeui r17, 4 79*4882a593Smuzhiyun l.bf 2b 80*4882a593Smuzhiyun l.addi r19, r19, 4 // Increase src 81*4882a593Smuzhiyun 82*4882a593Smuzhiyun /* When n > 0, copy the remaining bytes, otherwise jump to exit */ 83*4882a593Smuzhiyun l.sfeqi r17, 0 84*4882a593Smuzhiyun l.bf 4f 85*4882a593Smuzhiyun 86*4882a593Smuzhiyun /* Byte copy loop */ 87*4882a593Smuzhiyun3: l.addi r17, r17, -1 // Decrease n 88*4882a593Smuzhiyun l.sb 0(r19), r13 // *src = cccc 89*4882a593Smuzhiyun l.sfnei r17, 0 90*4882a593Smuzhiyun l.bf 3b 91*4882a593Smuzhiyun l.addi r19, r19, 1 // Increase src 92*4882a593Smuzhiyun 93*4882a593Smuzhiyun4: l.jr r9 94*4882a593Smuzhiyun l.ori r11, r3, 0 95