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kernel/linux-rt-4.4.41/arch/arm/lib/memset.S 2.71 KB
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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>
  #include <asm/unwind.h>
  
  	.text
  	.align	5
  
  ENTRY(mmioset)
  ENTRY(memset)
  UNWIND( .fnstart         )
  	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}
  UNWIND( .fnend              )
  UNWIND( .fnstart            )
  UNWIND( .save {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}
  UNWIND( .fnend              )
  
  #else
  
  /*
   * This version aligns the destination pointer in order to write
   * whole cache lines at once.
   */
  
  	stmfd	sp!, {r4-r8, lr}
  UNWIND( .fnend                 )
  UNWIND( .fnstart               )
  UNWIND( .save {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}
  UNWIND( .fnend                 )
  
  #endif
  
  UNWIND( .fnstart            )
  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
  	ret	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
  UNWIND( .fnend   )
  ENDPROC(memset)
  ENDPROC(mmioset)