sysdeps/alpha/strcat.S

   1 /* Copyright (C) 1996 Free Software Foundation, Inc.
   2    Contributed by Richard Henderson (rth@tamu.edu)
   3
   4 This file is part of the GNU C Library.
   5
   6 The GNU C Library is free software; you can redistribute it and/or
   7 modify it under the terms of the GNU Library General Public License as
   8 published by the Free Software Foundation; either version 2 of the
   9 License, or (at your option) any later version.
  10
  11 The GNU C Library is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 Library General Public License for more details.
  15
  16 You should have received a copy of the GNU Library General Public
  17 License along with the GNU C Library; see the file COPYING.LIB.  If
  18 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  19 Cambridge, MA 02139, USA.  */
  20
  21 /* Append a null-terminated string from SRC to DST.  */
  22
  23 #include <sysdep.h>
  24
  25         .text
  26
  27 ENTRY(strcat)
  28         ldgp    gp, 0(pv)
  29         .prologue 1
  30
  31         mov     a0, v0          # set up return value
  32
  33         /* Find the end of the string.  */
  34
  35         ldq_u   t0, 0(a0)       # load first quadword (a0 may be misaligned)
  36         lda     t1, -1(zero)
  37         insqh   t1, a0, t1
  38         andnot  a0, 7, a0
  39         or      t1, t0, t0
  40         cmpbge  zero, t0, t1    # t1 <- bitmask: bit i == 1 <==> i-th byte == 0
  41         bne     t1, $found
  42
  43 $loop:  ldq     t0, 8(a0)
  44         addq    a0, 8, a0       # addr += 8
  45         cmpbge  zero, t0, t1
  46         beq     t1, $loop
  47
  48 $found: negq    t1, t2          # clear all but least set bit
  49         and     t1, t2, t1
  50
  51         and     t1, 0xf0, t2    # binary search for that set bit
  52         and     t1, 0xcc, t3
  53         and     t1, 0xaa, t4
  54         cmovne  t2, 4, t2
  55         cmovne  t3, 2, t3
  56         cmovne  t4, 1, t4
  57         addq    t2, t3, t2
  58         addq    a0, t4, a0
  59         addq    a0, t2, a0
  60
  61         /* Now do the append.  */
  62
  63         jsr     t9, __stxcpy
  64         ret
  65
  66         END(strcat)