sysdeps/powerpc/powerpc64/stpcpy.S

   1 /* Optimized stpcpy implementation for PowerPC64.
   2    Copyright (C) 1997-2013 Free Software Foundation, Inc.
   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    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <sysdep.h>
  20 #include <bp-sym.h>
  21 #include <bp-asm.h>
  22
  23 /* See strlen.s for comments on how the end-of-string testing works.  */
  24
  25 /* char * [r3] stpcpy (char *dest [r3], const char *src [r4])  */
  26
  27 EALIGN (BP_SYM (__stpcpy), 4, 0)
  28         CALL_MCOUNT 2
  29
  30 #define rTMP    r0
  31 #define rRTN    r3
  32 #if __BOUNDED_POINTERS__
  33 # define rDEST  r4              /* pointer to previous word in dest */
  34 # define rSRC   r5              /* pointer to previous word in src */
  35 # define rLOW   r11
  36 # define rHIGH  r12
  37 #else
  38 # define rDEST  r3              /* pointer to previous word in dest */
  39 # define rSRC   r4              /* pointer to previous word in src */
  40 #endif
  41 #define rWORD   r6              /* current word from src */
  42 #define rFEFE   r7              /* 0xfefefeff */
  43 #define r7F7F   r8              /* 0x7f7f7f7f */
  44 #define rNEG    r9              /* ~(word in src | 0x7f7f7f7f) */
  45 #define rALT    r10             /* alternate word from src */
  46
  47         CHECK_BOUNDS_LOW (rSRC, rLOW, rHIGH)
  48         CHECK_BOUNDS_LOW (rDEST, rLOW, rHIGH)
  49         STORE_RETURN_BOUNDS (rLOW, rHIGH)
  50
  51         or      rTMP, rSRC, rDEST
  52         clrldi. rTMP, rTMP, 62
  53         addi    rDEST, rDEST, -4
  54         bne     L(unaligned)
  55
  56         lis     rFEFE, -0x101
  57         lis     r7F7F, 0x7f7f
  58         lwz     rWORD, 0(rSRC)
  59         addi    rFEFE, rFEFE, -0x101
  60         addi    r7F7F, r7F7F, 0x7f7f
  61         b       L(g2)
  62
  63 L(g0):  lwzu    rALT, 4(rSRC)
  64         stwu    rWORD, 4(rDEST)
  65         add     rTMP, rFEFE, rALT
  66         nor     rNEG, r7F7F, rALT
  67         and.    rTMP, rTMP, rNEG
  68         bne-    L(g1)
  69         lwzu    rWORD, 4(rSRC)
  70         stwu    rALT, 4(rDEST)
  71 L(g2):  add     rTMP, rFEFE, rWORD
  72         nor     rNEG, r7F7F, rWORD
  73         and.    rTMP, rTMP, rNEG
  74         beq+    L(g0)
  75
  76         mr      rALT, rWORD
  77 /* We've hit the end of the string.  Do the rest byte-by-byte.  */
  78 L(g1):  rlwinm. rTMP, rALT, 8, 24, 31
  79         stbu    rTMP, 4(rDEST)
  80         beqlr-
  81         rlwinm. rTMP, rALT, 16, 24, 31
  82         stbu    rTMP, 1(rDEST)
  83         beqlr-
  84         rlwinm. rTMP, rALT, 24, 24, 31
  85         stbu    rTMP, 1(rDEST)
  86         beqlr-
  87         stbu    rALT, 1(rDEST)
  88         CHECK_BOUNDS_HIGH (rDEST, rHIGH, twlgt)
  89         STORE_RETURN_VALUE (rDEST)
  90         blr
  91
  92 /* Oh well.  In this case, we just do a byte-by-byte copy.  */
  93         .align 4
  94         nop
  95 L(unaligned):
  96         lbz     rWORD, 0(rSRC)
  97         addi    rDEST, rDEST, 3
  98         cmpwi   rWORD, 0
  99         beq-    L(u2)
 100
 101 L(u0):  lbzu    rALT, 1(rSRC)
 102         stbu    rWORD, 1(rDEST)
 103         cmpwi   rALT, 0
 104         beq-    L(u1)
 105         nop             /* Let 601 load start of loop.  */
 106         lbzu    rWORD, 1(rSRC)
 107         stbu    rALT, 1(rDEST)
 108         cmpwi   rWORD, 0
 109         bne+    L(u0)
 110 L(u2):  stbu    rWORD, 1(rDEST)
 111         CHECK_BOUNDS_HIGH (rDEST, rHIGH, twlgt)
 112         STORE_RETURN_VALUE (rDEST)
 113         blr
 114 L(u1):  stbu    rALT, 1(rDEST)
 115         CHECK_BOUNDS_HIGH (rDEST, rHIGH, twlgt)
 116         STORE_RETURN_VALUE (rDEST)
 117         blr
 118 END (BP_SYM (__stpcpy))
 119
 120 weak_alias (BP_SYM (__stpcpy), BP_SYM (stpcpy))
 121 libc_hidden_def (__stpcpy)
 122 libc_hidden_builtin_def (stpcpy)