arch/blackfin/lib/memcmp.S

   1 /*
   2  * Copyright 2004-2009 Analog Devices Inc.
   3  *
   4  * Licensed under the Clear BSD license or the GPL-2 (or later)
   5  */
   6
   7 #include <linux/linkage.h>
   8
   9 /* int memcmp(const void *s1, const void *s2, size_t n);
  10  * R0 = First Address (s1)
  11  * R1 = Second Address (s2)
  12  * R2 = count (n)
  13  *
  14  * Favours word aligned data.
  15  */
  16
  17 .text
  18
  19 .align 2
  20
  21 ENTRY(_memcmp)
  22         I1 = P3;
  23         P0 = R0;                        /* P0 = s1 address */
  24         P3 = R1;                        /* P3 = s2 Address  */
  25         P2 = R2 ;                       /* P2 = count */
  26         CC = R2 <= 7(IU);
  27         IF CC JUMP .Ltoo_small;
  28         I0 = R1;                        /* s2 */
  29         R1 = R1 | R0;           /* OR addresses together */
  30         R1 <<= 30;              /* check bottom two bits */
  31         CC =  AZ;                       /* AZ set if zero. */
  32         IF !CC JUMP .Lbytes ;   /* Jump if addrs not aligned. */
  33
  34         P1 = P2 >> 2;           /* count = n/4 */
  35         R3 =  3;
  36         R2 = R2 & R3;           /* remainder */
  37         P2 = R2;                        /* set remainder */
  38
  39         LSETUP (.Lquad_loop_s, .Lquad_loop_e) LC0=P1;
  40 .Lquad_loop_s:
  41 #if ANOMALY_05000202
  42         R0 = [P0++];
  43         R1 = [I0++];
  44 #else
  45         MNOP || R0 = [P0++] || R1 = [I0++];
  46 #endif
  47         CC = R0 == R1;
  48         IF !CC JUMP .Lquad_different;
  49 .Lquad_loop_e:
  50         NOP;
  51
  52         P3 = I0;                        /* s2 */
  53 .Ltoo_small:
  54         CC = P2 == 0;           /* Check zero count*/
  55         IF CC JUMP .Lfinished;  /* very unlikely*/
  56
  57 .Lbytes:
  58         LSETUP (.Lbyte_loop_s, .Lbyte_loop_e) LC0=P2;
  59 .Lbyte_loop_s:
  60         R1 = B[P3++](Z);        /* *s2 */
  61         R0 = B[P0++](Z);        /* *s1 */
  62         CC = R0 == R1;
  63         IF !CC JUMP .Ldifferent;
  64 .Lbyte_loop_e:
  65         NOP;
  66
  67 .Ldifferent:
  68         R0 = R0 - R1;
  69         P3 = I1;
  70         RTS;
  71
  72 .Lquad_different:
  73         /* We've read two quads which don't match.
  74          * Can't just compare them, because we're
  75          * a little-endian machine, so the MSBs of
  76          * the regs occur at later addresses in the
  77          * string.
  78          * Arrange to re-read those two quads again,
  79          * byte-by-byte.
  80          */
  81         P0 += -4;               /* back up to the start of the */
  82         P3 = I0;                /* quads, and increase the*/
  83         P2 += 4;                /* remainder count*/
  84         P3 += -4;
  85         JUMP .Lbytes;
  86
  87 .Lfinished:
  88         R0 = 0;
  89         P3 = I1;
  90         RTS;
  91
  92 ENDPROC(_memcmp)