/* * linux/arch/arm/lib/memset.S * * Copyright (C) 1995-2000 Russell King * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * ASM optimised string functions */ #include <linux/linkage.h> #include <asm/assembler.h> .text .align 5 .word 0 1: subs r2, r2, #4 @ 1 do we have enough blt 5f @ 1 bytes to align with? cmp r3, #2 @ 1 strltb r1, [r0], #1 @ 1 strleb r1, [r0], #1 @ 1 strb r1, [r0], #1 @ 1 add r2, r2, r3 @ 1 (r2 = r2 - (4 - r3)) /* * The pointer is now aligned and the length is adjusted. Try doing the * memset again. */ ENTRY(memset) ands r3, r0, #3 @ 1 unaligned? bne 1b @ 1 /* * we know that the pointer in r0 is aligned to a word boundary. */ orr r1, r1, r1, lsl #8 orr r1, r1, r1, lsl #16 mov r3, r1 cmp r2, #16 blt 4f #if ! CALGN(1)+0 /* * We need an extra register for this loop - save the return address and * use the LR */ str lr, [sp, #-4]! mov ip, r1 mov lr, r1 2: subs r2, r2, #64 stmgeia r0!, {r1, r3, ip, lr} @ 64 bytes at a time. stmgeia r0!, {r1, r3, ip, lr} stmgeia r0!, {r1, r3, ip, lr} stmgeia r0!, {r1, r3, ip, lr} bgt 2b ldmeqfd sp!, {pc} @ Now <64 bytes to go. /* * No need to correct the count; we're only testing bits from now on */ tst r2, #32 stmneia r0!, {r1, r3, ip, lr} stmneia r0!, {r1, r3, ip, lr} tst r2, #16 stmneia r0!, {r1, r3, ip, lr} ldr lr, [sp], #4 #else /* * This version aligns the destination pointer in order to write * whole cache lines at once. */ stmfd sp!, {r4-r7, lr} mov r4, r1 mov r5, r1 mov r6, r1 mov r7, r1 mov ip, r1 mov lr, r1 cmp r2, #96 tstgt r0, #31 ble 3f and ip, r0, #31 rsb ip, ip, #32 sub r2, r2, ip movs ip, ip, lsl #(32 - 4) stmcsia r0!, {r4, r5, r6, r7} stmmiia r0!, {r4, r5} tst ip, #(1 << 30) mov ip, r1 strne r1, [r0], #4 3: subs r2, r2, #64 stmgeia r0!, {r1, r3-r7, ip, lr} stmgeia r0!, {r1, r3-r7, ip, lr} bgt 3b ldmeqfd sp!, {r4-r7, pc} tst r2, #32 stmneia r0!, {r1, r3-r7, ip, lr} tst r2, #16 stmneia r0!, {r4-r7} ldmfd sp!, {r4-r7, lr} #endif 4: tst r2, #8 stmneia r0!, {r1, r3} tst r2, #4 strne r1, [r0], #4 /* * When we get here, we've got less than 4 bytes to zero. We * may have an unaligned pointer as well. */ 5: tst r2, #2 strneb r1, [r0], #1 strneb r1, [r0], #1 tst r2, #1 strneb r1, [r0], #1 mov pc, lr ENDPROC(memset)