arch/blackfin/lib/memcpy.S

   1 /*
   2  * internal version of memcpy(), issued by the compiler to copy blocks of
   3  * data around. This is really memmove() - it has to be able to deal with
   4  * possible overlaps, because that ambiguity is when the compiler gives up
   5  * and calls a function. We have our own, internal version so that we get
   6  * something we trust, even if the user has redefined the normal symbol.
   7  *
   8  * Copyright 2004-2009 Analog Devices Inc.
   9  *
  10  * Licensed under the Clear BSD license or the GPL-2 (or later)
  11  */
  12
  13 #include <linux/linkage.h>
  14
  15 /* void *memcpy(void *dest, const void *src, size_t n);
  16  * R0 = To Address (dest) (leave unchanged to form result)
  17  * R1 = From Address (src)
  18  * R2 = count
  19  *
  20  * Note: Favours word alignment
  21  */
  22
  23 #ifdef CONFIG_MEMCPY_L1
  24 .section .l1.text
  25 #else
  26 .text
  27 #endif
  28
  29 .align 2
  30
  31 ENTRY(_memcpy)
  32         CC = R2 <=  0;  /* length not positive? */
  33         IF CC JUMP .L_P1L2147483647;    /* Nothing to do */
  34
  35         P0 = R0 ;       /* dst*/
  36         P1 = R1 ;       /* src*/
  37         P2 = R2 ;       /* length */
  38
  39         /* check for overlapping data */
  40         CC = R1 < R0;   /* src < dst */
  41         IF !CC JUMP .Lno_overlap;
  42         R3 = R1 + R2;
  43         CC = R0 < R3;   /* and dst < src+len */
  44         IF CC JUMP .Lhas_overlap;
  45
  46 .Lno_overlap:
  47         /* Check for aligned data.*/
  48
  49         R3 = R1 | R0;
  50         R1 = 0x3;
  51         R3 = R3 & R1;
  52         CC = R3;        /* low bits set on either address? */
  53         IF CC JUMP .Lnot_aligned;
  54
  55         /* Both addresses are word-aligned, so we can copy
  56         at least part of the data using word copies.*/
  57         P2 = P2 >> 2;
  58         CC = P2 <= 2;
  59         IF !CC JUMP .Lmore_than_seven;
  60         /* less than eight bytes... */
  61         P2 = R2;
  62         LSETUP(.Lthree_start, .Lthree_end) LC0=P2;
  63 .Lthree_start:
  64         R3 = B[P1++] (X);
  65 .Lthree_end:
  66         B[P0++] = R3;
  67
  68         RTS;
  69
  70 .Lmore_than_seven:
  71         /* There's at least eight bytes to copy. */
  72         P2 += -1;       /* because we unroll one iteration */
  73         LSETUP(.Lword_loops, .Lword_loope) LC0=P2;
  74         I1 = P1;
  75         R3 = [I1++];
  76 #if ANOMALY_05000202
  77 .Lword_loops:
  78         [P0++] = R3;
  79 .Lword_loope:
  80         R3 = [I1++];
  81 #else
  82 .Lword_loops:
  83 .Lword_loope:
  84         MNOP || [P0++] = R3 || R3 = [I1++];
  85 #endif
  86         [P0++] = R3;
  87         /* Any remaining bytes to copy? */
  88         R3 = 0x3;
  89         R3 = R2 & R3;
  90         CC = R3 == 0;
  91         P1 = I1;        /* in case there's something left, */
  92         IF !CC JUMP .Lbytes_left;
  93         RTS;
  94 .Lbytes_left:   P2 = R3;
  95 .Lnot_aligned:
  96         /* From here, we're copying byte-by-byte. */
  97         LSETUP (.Lbyte_start, .Lbyte_end) LC0=P2;
  98 .Lbyte_start:
  99         R1 = B[P1++] (X);
 100 .Lbyte_end:
 101         B[P0++] = R1;
 102
 103 .L_P1L2147483647:
 104         RTS;
 105
 106 .Lhas_overlap:
 107         /* Need to reverse the copying, because the
 108          * dst would clobber the src.
 109          * Don't bother to work out alignment for
 110          * the reverse case.
 111          */
 112         P0 = P0 + P2;
 113         P0 += -1;
 114         P1 = P1 + P2;
 115         P1 += -1;
 116         LSETUP(.Lover_start, .Lover_end) LC0=P2;
 117 .Lover_start:
 118         R1 = B[P1--] (X);
 119 .Lover_end:
 120         B[P0--] = R1;
 121
 122         RTS;
 123
 124 ENDPROC(_memcpy)