/* * 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 <arch/asm.h> #include "asmlib.h" ENTRY(memset) ands r3, r0, #3 @ 1 unaligned? mov ip, r0 @ preserve r0 as return value bne 6f @ 1 /* * we know that the pointer in ip is aligned to a word boundary. */ 1: 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 2 extra registers for this loop - use r8 and the LR */ stmfd sp!, {r8, lr} mov r8, r1 mov lr, r1 2: subs r2, r2, #64 stmgeia ip!, {r1, r3, r8, lr} @ 64 bytes at a time. stmgeia ip!, {r1, r3, r8, lr} stmgeia ip!, {r1, r3, r8, lr} stmgeia ip!, {r1, r3, r8, lr} bgt 2b ldmeqfd sp!, {r8, pc} @ Now <64 bytes to go. /* * No need to correct the count; we're only testing bits from now on */ tst r2, #32 stmneia ip!, {r1, r3, r8, lr} stmneia ip!, {r1, r3, r8, lr} tst r2, #16 stmneia ip!, {r1, r3, r8, lr} ldmfd sp!, {r8, lr} #else /* * This version aligns the destination pointer in order to write * whole cache lines at once. */ stmfd sp!, {r4-r8, lr} mov r4, r1 mov r5, r1 mov r6, r1 mov r7, r1 mov r8, r1 mov lr, r1 cmp r2, #96 tstgt ip, #31 ble 3f and r8, ip, #31 rsb r8, r8, #32 sub r2, r2, r8 movs r8, r8, lsl #(32 - 4) stmcsia ip!, {r4, r5, r6, r7} stmmiia ip!, {r4, r5} tst r8, #(1 << 30) mov r8, r1 strne r1, [ip], #4 3: subs r2, r2, #64 stmgeia ip!, {r1, r3-r8, lr} stmgeia ip!, {r1, r3-r8, lr} bgt 3b ldmeqfd sp!, {r4-r8, pc} tst r2, #32 stmneia ip!, {r1, r3-r8, lr} tst r2, #16 stmneia ip!, {r4-r7} ldmfd sp!, {r4-r8, lr} #endif 4: tst r2, #8 stmneia ip!, {r1, r3} tst r2, #4 strne r1, [ip], #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, [ip], #1 strneb r1, [ip], #1 tst r2, #1 strneb r1, [ip], #1 mov pc, lr 6: subs r2, r2, #4 @ 1 do we have enough blt 5b @ 1 bytes to align with? cmp r3, #2 @ 1 strltb r1, [ip], #1 @ 1 strleb r1, [ip], #1 @ 1 strb r1, [ip], #1 @ 1 add r2, r2, r3 @ 1 (r2 = r2 - (4 - r3)) b 1b ENDPROC(memset)