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kernel/linux-imx6_3.14.28/arch/blackfin/lib/memset.S 1.8 KB
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  /*
   * Copyright 2004-2009 Analog Devices Inc.
   *
   * Licensed under the Clear BSD license or the GPL-2 (or later)
   */
  
  #include <linux/linkage.h>
  
  .align 2
  
  #ifdef CONFIG_MEMSET_L1
  .section .l1.text
  #else
  .text
  #endif
  
  /*
   * C Library function MEMSET
   * R0 = address (leave unchanged to form result)
   * R1 = filler byte
   * R2 = count
   * Favours word aligned data.
   * The strncpy assumes that I0 and I1 are not used in this function
   */
  
  ENTRY(_memset)
  	P0 = R0 ;              /* P0 = address */
  	P2 = R2 ;              /* P2 = count   */
  	R3 = R0 + R2;          /* end          */
  	CC = R2 <= 7(IU);
  	IF CC JUMP  .Ltoo_small;
  	R1 = R1.B (Z);         /* R1 = fill char */
  	R2 =  3;
  	R2 = R0 & R2;          /* addr bottom two bits */
  	CC =  R2 == 0;             /* AZ set if zero.	*/
  	IF !CC JUMP  .Lforce_align ;  /* Jump if addr not aligned. */
  
  .Laligned:
  	P1 = P2 >> 2;          /* count = n/4        */
  	R2 = R1 <<  8;         /* create quad filler */
  	R2.L = R2.L + R1.L(NS);
  	R2.H = R2.L + R1.H(NS);
  	P2 = R3;
  
  	LSETUP (.Lquad_loop , .Lquad_loop) LC0=P1;
  .Lquad_loop:
  	[P0++] = R2;
  
  	CC = P0 == P2;
  	IF !CC JUMP .Lbytes_left;
  	RTS;
  
  .Lbytes_left:
  	R2 = R3;                /* end point */
  	R3 = P0;                /* current position */
  	R2 = R2 - R3;           /* bytes left */
  	P2 = R2;
  
  .Ltoo_small:
  	CC = P2 == 0;           /* Check zero count */
  	IF CC JUMP .Lfinished;    /* Unusual */
  
  .Lbytes:
  	LSETUP (.Lbyte_loop , .Lbyte_loop) LC0=P2;
  .Lbyte_loop:
  	B[P0++] = R1;
  
  .Lfinished:
  	RTS;
  
  .Lforce_align:
  	CC = BITTST (R0, 0);  /* odd byte */
  	R0 = 4;
  	R0 = R0 - R2;
  	P1 = R0;
  	R0 = P0;		    /* Recover return address */
  	IF !CC JUMP .Lskip1;
  	B[P0++] = R1;
  .Lskip1:
  	CC = R2 <= 2;          /* 2 bytes */
  	P2 -= P1;              /* reduce count */
  	IF !CC JUMP .Laligned;
  	B[P0++] = R1;
  	B[P0++] = R1;
  	JUMP .Laligned;
  
  ENDPROC(_memset)