sysdeps/alpha/alphaev67/stpncpy.S

   1 /* Copyright (C) 2000-2019 Free Software Foundation, Inc.
   2    Contributed by Richard Henderson (rth@redhat.com)
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library.  If not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 /* Copy no more than N bytes from SRC to DEST, returning the address of
  20    the terminating '\0' in DEST.  */
  21
  22 #include <sysdep.h>
  23
  24         .arch ev6
  25         .set noat
  26         .set noreorder
  27         .text
  28
  29 ENTRY(__stpncpy)
  30         ldgp    gp, 0(pv)
  31 #ifdef PROF
  32         lda     AT, _mcount
  33         jsr     AT, (AT), _mcount
  34 #endif
  35         .prologue 1
  36
  37         mov     a0, v0
  38         beq     a2, $zerocount
  39
  40         .align 4
  41         nop
  42         nop
  43         jsr     t9, __stxncpy   # do the work of the copy
  44
  45         cttz    t8, t4
  46         zapnot  t0, t8, t5
  47         andnot  a0, 7, a0
  48         bne     a2, $multiword  # do we have full words left?
  49
  50         subq    t8, 1, t2
  51         subq    t10, 1, t3
  52         cmpult  zero, t5, t5
  53         addq    a0, t4, v0
  54
  55         or      t2, t8, t2
  56         or      t3, t10, t3
  57         addq    v0, t5, v0
  58         andnot  t3, t2, t3
  59
  60         zap     t0, t3, t0
  61         nop
  62         stq     t0, 0(a0)
  63         ret
  64
  65 $multiword:
  66         subq    t8, 1, t7       # clear the final bits in the prev word
  67         cmpult  zero, t5, t5
  68         or      t7, t8, t7
  69         zapnot  t0, t7, t0
  70
  71         subq    a2, 1, a2
  72         stq     t0, 0(a0)
  73         addq    a0, 8, a1
  74         beq     a2, 1f          # loop over full words remaining
  75
  76         nop
  77         nop
  78         nop
  79         blbc    a2, 0f
  80
  81         stq     zero, 0(a1)
  82         subq    a2, 1, a2
  83         addq    a1, 8, a1
  84         beq     a2, 1f
  85
  86 0:      stq     zero, 0(a1)
  87         subq    a2, 2, a2
  88         nop
  89         nop
  90
  91         stq     zero, 8(a1)
  92         addq    a1, 16, a1
  93         nop
  94         bne     a2, 0b
  95
  96 1:      ldq     t0, 0(a1)       # clear the leading bits in the final word
  97         subq    t10, 1, t7
  98         addq    a0, t4, v0
  99         nop
 100
 101         or      t7, t10, t7
 102         addq    v0, t5, v0
 103         zap     t0, t7, t0
 104         stq     t0, 0(a1)
 105
 106 $zerocount:
 107         nop
 108         nop
 109         nop
 110         ret
 111
 112         END(__stpncpy)
 113
 114 libc_hidden_def (__stpncpy)
 115 weak_alias (__stpncpy, stpncpy)