LXR linux/arch/arc/lib/strcpy-700.S

   1/*
   2 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License version 2 as
   6 * published by the Free Software Foundation.
   7 */
   8
   9/* If dst and src are 4 byte aligned, copy 8 bytes at a time.
  10   If the src is 4, but not 8 byte aligned, we first read 4 bytes to get
  11   it 8 byte aligned.  Thus, we can do a little read-ahead, without
  12   dereferencing a cache line that we should not touch.
  13   Note that short and long instructions have been scheduled to avoid
  14   branch stalls.
  15   The beq_s to r3z could be made unaligned & long to avoid a stall
  16   there, but the it is not likely to be taken often, and it
  17   would also be likey to cost an unaligned mispredict at the next call.  */
  18
  19#include <asm/linkage.h>
  20
  21ARC_ENTRY strcpy
  22        or      r2,r0,r1
  23        bmsk_s  r2,r2,1
  24        brne.d  r2,0,charloop
  25        mov_s   r10,r0
  26        ld_s    r3,[r1,0]
  27        mov     r8,0x01010101
  28        bbit0.d r1,2,loop_start
  29        ror     r12,r8
  30        sub     r2,r3,r8
  31        bic_s   r2,r2,r3
  32        tst_s   r2,r12
  33        bne     r3z
  34        mov_s   r4,r3
  35        .balign 4
  36loop:
  37        ld.a    r3,[r1,4]
  38        st.ab   r4,[r10,4]
  39loop_start:
  40        ld.a    r4,[r1,4]
  41        sub     r2,r3,r8
  42        bic_s   r2,r2,r3
  43        tst_s   r2,r12
  44        bne_s   r3z
  45        st.ab   r3,[r10,4]
  46        sub     r2,r4,r8
  47        bic     r2,r2,r4
  48        tst     r2,r12
  49        beq     loop
  50        mov_s   r3,r4
  51#ifdef __LITTLE_ENDIAN__
  52r3z:    bmsk.f  r1,r3,7
  53        lsr_s   r3,r3,8
  54#else
  55r3z:    lsr.f   r1,r3,24
  56        asl_s   r3,r3,8
  57#endif
  58        bne.d   r3z
  59        stb.ab  r1,[r10,1]
  60        j_s     [blink]
  61
  62        .balign 4
  63charloop:
  64        ldb.ab  r3,[r1,1]
  65
  66
  67        brne.d  r3,0,charloop
  68        stb.ab  r3,[r10,1]
  69        j       [blink]
  70ARC_EXIT strcpy
  71