sysdeps/alpha/alphaev67/strncat.S

   1 /* Copyright (C) 2000-2019 Free Software Foundation, Inc.
   2    Contributed by Richard Henderson <rth@tamu.edu>, 1996.
   3    EV67 optimized by Rick Gorton <rick.gorton@alpha-processor.com>.
   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 Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the 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    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library.  If not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 /* Append no more than COUNT characters from the null-terminated string SRC
  21    to the null-terminated string DST.  Always null-terminate the new DST.  */
  22
  23 #include <sysdep.h>
  24
  25         .arch ev6
  26         .set noreorder
  27         .text
  28
  29 ENTRY(strncat)
  30         ldgp    gp, 0(pv)
  31 #ifdef PROF
  32         .set noat
  33         lda     AT, _mcount
  34         jsr     AT, (AT), _mcount
  35         .set at
  36 #endif
  37         .prologue 1
  38
  39         mov     a0, v0          # set up return value
  40         beq     a2, $zerocount  # U :
  41         /* Find the end of the string.  */
  42         ldq_u   t0, 0(a0)       # L : load first quadword (a0 may be misaligned)
  43         lda     t1, -1          # E :
  44
  45         insqh   t1, v0, t1      # U :
  46         andnot  a0, 7, a0       # E :
  47         nop                     # E :
  48         or      t1, t0, t0      # E :
  49
  50         nop                     # E :
  51         nop                     # E :
  52         cmpbge  zero, t0, t1    # E : bits set iff byte == 0
  53         bne     t1, $found      # U :
  54
  55 $loop:  ldq     t0, 8(a0)       # L :
  56         addq    a0, 8, a0       # E :
  57         cmpbge  zero, t0, t1    # E :
  58         beq     t1, $loop       # U :
  59
  60 $found: cttz    t1, t2          # U0 :
  61         addq    a0, t2, a0      # E :
  62         jsr     t9, __stxncpy   # L0 : Now do the append.
  63
  64         /* Worry about the null termination.  */
  65
  66         cttz    t10, t2         # U0: byte offset of end-of-count.
  67         bic     a0, 7, a0       # E : word align the last write address.
  68         zapnot  t0, t8, t1      # U : was last byte a null?
  69         nop                     # E :
  70
  71         bne     t1, 0f          # U :
  72         nop                     # E :
  73         nop                     # E :
  74         ret                     # L0 :
  75
  76 0:      addq    t2, a0, a0      # E : address of end-of-count
  77         stb     zero, 1(a0)     # L :
  78         nop                     # E :
  79         ret                     # L0 :
  80
  81 $zerocount:
  82         nop                     # E :
  83         nop                     # E :
  84         nop                     # E :
  85         ret                     # L0 :
  86
  87         END(strncat)