arch/alpha/lib/strcat.S

   1 /*
   2  * arch/alpha/lib/strcat.S
   3  * Contributed by Richard Henderson (rth@tamu.edu)
   4  *
   5  * Append a null-terminated string from SRC to DST.
   6  */
   7 #include <asm/export.h>
   8
   9         .text
  10
  11         .align 3
  12         .globl strcat
  13         .ent strcat
  14 strcat:
  15         .frame $30, 0, $26
  16         .prologue 0
  17
  18         mov     $16, $0         # set up return value
  19
  20         /* Find the end of the string.  */
  21
  22         ldq_u   $1, 0($16)      # load first quadword (a0 may be misaligned)
  23         lda     $2, -1
  24         insqh   $2, $16, $2
  25         andnot  $16, 7, $16
  26         or      $2, $1, $1
  27         cmpbge  $31, $1, $2     # bits set iff byte == 0
  28         bne     $2, $found
  29
  30 $loop:  ldq     $1, 8($16)
  31         addq    $16, 8, $16
  32         cmpbge  $31, $1, $2
  33         beq     $2, $loop
  34
  35 $found: negq    $2, $3          # clear all but least set bit
  36         and     $2, $3, $2
  37
  38         and     $2, 0xf0, $3    # binary search for that set bit
  39         and     $2, 0xcc, $4
  40         and     $2, 0xaa, $5
  41         cmovne  $3, 4, $3
  42         cmovne  $4, 2, $4
  43         cmovne  $5, 1, $5
  44         addq    $3, $4, $3
  45         addq    $16, $5, $16
  46         addq    $16, $3, $16
  47
  48         /* Now do the append.  */
  49
  50         mov     $26, $23
  51         br      __stxcpy
  52
  53         .end strcat
  54 EXPORT_SYMBOL(strcat);