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kernel/linux-imx6_3.14.28/arch/blackfin/lib/memcpy.S 2.61 KB
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  /*
   * internal version of memcpy(), issued by the compiler to copy blocks of
   * data around. This is really memmove() - it has to be able to deal with
   * possible overlaps, because that ambiguity is when the compiler gives up
   * and calls a function. We have our own, internal version so that we get
   * something we trust, even if the user has redefined the normal symbol.
   *
   * Copyright 2004-2009 Analog Devices Inc.
   *
   * Licensed under the Clear BSD license or the GPL-2 (or later)
   */
  
  #include <linux/linkage.h>
  
  /* void *memcpy(void *dest, const void *src, size_t n);
   * R0 = To Address (dest) (leave unchanged to form result)
   * R1 = From Address (src)
   * R2 = count
   *
   * Note: Favours word alignment
   */
  
  #ifdef CONFIG_MEMCPY_L1
  .section .l1.text
  #else
  .text
  #endif
  
  .align 2
  
  ENTRY(_memcpy)
  	CC = R2 <=  0;	/* length not positive? */
  	IF CC JUMP .L_P1L2147483647;	/* Nothing to do */
  
  	P0 = R0 ;	/* dst*/
  	P1 = R1 ;	/* src*/
  	P2 = R2 ;	/* length */
  
  	/* check for overlapping data */
  	CC = R1 < R0;	/* src < dst */
  	IF !CC JUMP .Lno_overlap;
  	R3 = R1 + R2;
  	CC = R0 < R3;	/* and dst < src+len */
  	IF CC JUMP .Lhas_overlap;
  
  .Lno_overlap:
  	/* Check for aligned data.*/
  
  	R3 = R1 | R0;
  	R1 = 0x3;
  	R3 = R3 & R1;
  	CC = R3;	/* low bits set on either address? */
  	IF CC JUMP .Lnot_aligned;
  
  	/* Both addresses are word-aligned, so we can copy
  	at least part of the data using word copies.*/
  	P2 = P2 >> 2;
  	CC = P2 <= 2;
  	IF !CC JUMP .Lmore_than_seven;
  	/* less than eight bytes... */
  	P2 = R2;
  	LSETUP(.Lthree_start, .Lthree_end) LC0=P2;
  .Lthree_start:
  	R3 = B[P1++] (X);
  .Lthree_end:
  	B[P0++] = R3;
  
  	RTS;
  
  .Lmore_than_seven:
  	/* There's at least eight bytes to copy. */
  	P2 += -1;	/* because we unroll one iteration */
  	LSETUP(.Lword_loops, .Lword_loope) LC0=P2;
  	I1 = P1;
  	R3 = [I1++];
  #if ANOMALY_05000202
  .Lword_loops:
  	[P0++] = R3;
  .Lword_loope:
  	R3 = [I1++];
  #else
  .Lword_loops:
  .Lword_loope:
  	MNOP || [P0++] = R3 || R3 = [I1++];
  #endif
  	[P0++] = R3;
  	/* Any remaining bytes to copy? */
  	R3 = 0x3;
  	R3 = R2 & R3;
  	CC = R3 == 0;
  	P1 = I1;	/* in case there's something left, */
  	IF !CC JUMP .Lbytes_left;
  	RTS;
  .Lbytes_left:	P2 = R3;
  .Lnot_aligned:
  	/* From here, we're copying byte-by-byte. */
  	LSETUP (.Lbyte_start, .Lbyte_end) LC0=P2;
  .Lbyte_start:
  	R1 = B[P1++] (X);
  .Lbyte_end:
  	B[P0++] = R1;
  
  .L_P1L2147483647:
  	RTS;
  
  .Lhas_overlap:
  	/* Need to reverse the copying, because the
  	 * dst would clobber the src.
  	 * Don't bother to work out alignment for
  	 * the reverse case.
  	 */
  	P0 = P0 + P2;
  	P0 += -1;
  	P1 = P1 + P2;
  	P1 += -1;
  	LSETUP(.Lover_start, .Lover_end) LC0=P2;
  .Lover_start:
  	R1 = B[P1--] (X);
  .Lover_end:
  	B[P0--] = R1;
  
  	RTS;
  
  ENDPROC(_memcpy)