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56e70371a6
* sysdeps/alpha/_mcount.S, sysdeps/alpha/bb_init_func.S, sysdeps/alpha/bsd-_setjmp.S, sysdeps/alpha/bsd-setjmp.S, sysdeps/alpha/copysign.S, sysdeps/alpha/divrem.h, sysdeps/alpha/fabs.S, sysdeps/alpha/ffs.S, sysdeps/alpha/htonl.S, sysdeps/alpha/htons.S, sysdeps/alpha/memchr.S, sysdeps/alpha/setjmp.S, sysdeps/alpha/strlen.S, sysdeps/unix/sysv/linux/alpha/ieee_get_fp_control.S, sysdeps/unix/sysv/linux/alpha/ieee_set_fp_control.S, sysdeps/unix/sysv/linux/alpha/llseek.S, sysdeps/unix/sysv/linux/alpha/pipe.S, sysdeps/unix/sysv/linux/alpha/sigsuspend.S, sysdeps/unix/sysv/linux/alpha/sysdep.S: Use END macro instead of .end directive.
71 lines
2.2 KiB
ArmAsm
71 lines
2.2 KiB
ArmAsm
/* Copyright (C) 1996 Free Software Foundation, Inc.
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Contributed by David Mosberger (davidm@cs.arizona.edu).
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 675 Mass Ave,
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Cambridge, MA 02139, USA. */
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/* Finds length of a 0-terminated string. Optimized for the Alpha
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architecture:
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- memory accessed as aligned quadwords only
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- uses bcmpge to compare 8 bytes in parallel
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- does binary search to find 0 byte in last
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quadword (HAKMEM needed 12 instructions to
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do this instead of the 9 instructions that
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binary search needs). */
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#include <sysdep.h>
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.set noreorder
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.set noat
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ENTRY(strlen)
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ldq_u t0, 0(a0) # load first quadword (a0 may be misaligned)
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lda t1, -1(zero)
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insqh t1, a0, t1
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andnot a0, 7, v0
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or t1, t0, t0
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cmpbge zero, t0, t1 # t1 <- bitmask: bit i == 1 <==> i-th byte == 0
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bne t1, found
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loop: ldq t0, 8(v0)
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addq v0, 8, v0 # addr += 8
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nop # helps dual issue last two insns
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cmpbge zero, t0, t1
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beq t1, loop
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found: blbs t1, done # make aligned case fast
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negq t1, t2
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and t1, t2, t1
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and t1, 0x0f, t0
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addq v0, 4, t2
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cmoveq t0, t2, v0
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and t1, 0x33, t0
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addq v0, 2, t2
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cmoveq t0, t2, v0
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and t1, 0x55, t0
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addq v0, 1, t2
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cmoveq t0, t2, v0
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done: subq v0, a0, v0
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ret
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END(strlen)
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