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| /*
| * 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
|
| .syntax unified
| #if CONFIG_IS_ENABLED(SYS_THUMB_BUILD) && !defined(MEMSET_NO_THUMB_BUILD)
| .thumb
| .thumb_func
| #endif
| 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
| stmiage ip!, {r1, r3, r8, lr} @ 64 bytes at a time.
| stmiage ip!, {r1, r3, r8, lr}
| stmiage ip!, {r1, r3, r8, lr}
| stmiage ip!, {r1, r3, r8, lr}
| bgt 2b
| ldmfdeq 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
| stmiane ip!, {r1, r3, r8, lr}
| stmiane ip!, {r1, r3, r8, lr}
| tst r2, #16
| stmiane 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)
| stmiacs ip!, {r4, r5, r6, r7}
| stmiami ip!, {r4, r5}
| tst r8, #(1 << 30)
| mov r8, r1
| strne r1, [ip], #4
|
| 3: subs r2, r2, #64
| stmiage ip!, {r1, r3-r8, lr}
| stmiage ip!, {r1, r3-r8, lr}
| bgt 3b
| ldmfdeq sp!, {r4-r8, pc}
|
| tst r2, #32
| stmiane ip!, {r1, r3-r8, lr}
| tst r2, #16
| stmiane ip!, {r4-r7}
| ldmfd sp!, {r4-r8, lr}
|
| #endif
|
| 4: tst r2, #8
| stmiane 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
| strbne r1, [ip], #1
| strbne r1, [ip], #1
| tst r2, #1
| strbne r1, [ip], #1
| ret lr
|
| 6: subs r2, r2, #4 @ 1 do we have enough
| blt 5b @ 1 bytes to align with?
| cmp r3, #2 @ 1
| strblt r1, [ip], #1 @ 1
| strble r1, [ip], #1 @ 1
| strb r1, [ip], #1 @ 1
| add r2, r2, r3 @ 1 (r2 = r2 - (4 - r3))
| b 1b
| ENDPROC(memset)
|
|
