173 lines
5.7 KiB
ArmAsm
173 lines
5.7 KiB
ArmAsm
/* Determine the length of a string. For SPARC v9.
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Copyright (C) 1998, 1999 Free Software Foundation, Inc.
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Contributed by Jan Vondrak <jvon4518@ss1000.ms.mff.cuni.cz> and
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Jakub Jelinek <jj@ultra.linux.cz>.
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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 not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include <sysdep.h>
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#include <asm/asi.h>
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/* Normally, this uses
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((xword - 0x0101010101010101) & 0x8080808080808080) test
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to find out if any byte in xword could be zero. This is fast, but
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also gives false alarm for any byte in range 0x81-0xff. It does
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not matter for correctness, as if this test tells us there could
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be some zero byte, we check it byte by byte, but if bytes with
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high bits set are common in the strings, then this will give poor
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performance. You can #define EIGHTBIT_NOT_RARE and the algorithm
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will use one tick slower, but more precise test
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((xword - 0x0101010101010101) & (~xword) & 0x8080808080808080),
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which does not give any false alarms (but if some bits are set,
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one cannot assume from it which bytes are zero and which are not).
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It is yet to be measured, what is the correct default for glibc
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in these days for an average user.
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*/
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.text
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.align 32
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ENTRY(strlen)
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sethi %hi(0x01010101), %g1 /* IEU0 Group */
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ldub [%o0], %o3 /* Load */
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or %g1, %lo(0x01010101), %g1 /* IEU0 Group */
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mov %o0, %o1 /* IEU1 */
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sllx %g1, 32, %g4 /* IEU0 Group */
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andcc %o0, 7, %g0 /* IEU1 */
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or %g1, %g4, %g1 /* IEU0 Group */
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brz,pn %o3, 13f /* CTI+IEU1 */
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sllx %g1, 7, %g4 /* IEU0 Group */
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bne,a,pn %icc, 15f /* CTI */
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add %o0, 1, %o0 /* IEU1 */
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/* %g1 = 0x0101010101010101 *
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* %g4 = 0x8080808080808080 *
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* %o0 = string pointer *
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* %o1 = start of string */
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1: ldx [%o0], %o3 /* Load Group */
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add %o0, 8, %o0 /* IEU1 */
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2: sub %o3, %g1, %o2 /* IEU0 Group */
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#ifdef EIGHTBIT_NOT_RARE
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andn %o2, %o3, %o5 /* IEU0 Group */
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ldxa [%o0] ASI_PNF, %o3 /* Load */
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andcc %o5, %g4, %g0 /* IEU1 Group */
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#else
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ldxa [%o0] ASI_PNF, %o3 /* Load */
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andcc %o2, %g4, %g0 /* IEU1 Group */
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#endif
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be,pt %xcc, 2b /* CTI */
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add %o0, 8, %o0 /* IEU0 */
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addcc %o2, %g1, %g5 /* IEU1 Group */
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#ifdef EIGHTBIT_NOT_RARE
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srlx %o5, 32, %o5 /* IEU0 */
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3: andcc %o5, %g4, %g0 /* IEU1 Group */
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#else
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srlx %o2, 32, %o2 /* IEU0 */
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3: andcc %o2, %g4, %g0 /* IEU1 Group */
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#endif
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be,pn %xcc, 4f /* CTI */
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srlx %g5, 56, %o2 /* IEU0 */
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andcc %o2, 0xff, %g0 /* IEU1 Group */
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be,pn %icc, 12f /* CTI */
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srlx %g5, 48, %o2 /* IEU0 */
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andcc %o2, 0xff, %g0 /* IEU1 Group */
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be,pn %icc, 11f /* CTI */
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srlx %g5, 40, %o2 /* IEU0 */
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andcc %o2, 0xff, %g0 /* IEU1 Group */
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be,pn %icc, 10f /* CTI */
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srlx %g5, 32, %o2 /* IEU0 */
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andcc %o2, 0xff, %g0 /* IEU1 Group */
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be,pn %icc, 9f /* CTI */
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4: srlx %g5, 24, %o2 /* IEU0 */
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andcc %o2, 0xff, %g0 /* IEU1 Group */
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be,pn %icc, 8f /* CTI */
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srlx %g5, 16, %o2 /* IEU0 */
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andcc %o2, 0xff, %g0 /* IEU1 Group */
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be,pn %icc, 7f /* CTI */
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srlx %g5, 8, %o2 /* IEU0 */
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andcc %o2, 0xff, %g0 /* IEU1 Group */
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be,pn %icc, 6f /* CTI */
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sub %o3, %g1, %o2 /* IEU0 */
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andcc %g5, 0xff, %g0 /* IEU1 Group */
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be,pn %icc, 5f /* CTI */
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ldxa [%o0] ASI_PNF, %o3 /* Load */
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andcc %o2, %g4, %g0 /* IEU1 Group */
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be,pt %xcc, 2b /* CTI */
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add %o0, 8, %o0 /* IEU0 */
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addcc %o2, %g1, %g5 /* IEU1 Group */
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ba,pt %xcc, 3b /* CTI */
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srlx %o2, 32, %o2 /* IEU0 */
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5: add %o0, -9, %o0 /* IEU0 Group */
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retl /* CTI+IEU1 Group */
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sub %o0, %o1, %o0 /* IEU0 */
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6: add %o0, -10, %o0 /* IEU0 Group */
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retl /* CTI+IEU1 Group */
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sub %o0, %o1, %o0 /* IEU0 */
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7: add %o0, -11, %o0 /* IEU0 Group */
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retl /* CTI+IEU1 Group */
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sub %o0, %o1, %o0 /* IEU0 */
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8: add %o0, -12, %o0 /* IEU0 Group */
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retl /* CTI+IEU1 Group */
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sub %o0, %o1, %o0 /* IEU0 */
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9: add %o0, -13, %o0 /* IEU0 Group */
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retl /* CTI+IEU1 Group */
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sub %o0, %o1, %o0 /* IEU0 */
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10: add %o0, -14, %o0 /* IEU0 Group */
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retl /* CTI+IEU1 Group */
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sub %o0, %o1, %o0 /* IEU0 */
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11: add %o0, -15, %o0 /* IEU0 Group */
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retl /* CTI+IEU1 Group */
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sub %o0, %o1, %o0 /* IEU0 */
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12: add %o0, -16, %o0 /* IEU0 Group */
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retl /* CTI+IEU1 Group */
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sub %o0, %o1, %o0 /* IEU0 */
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13: retl /* CTI+IEU1 Group */
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mov 0, %o0 /* IEU0 */
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nop
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15: ldub [%o0], %o3 /* Load Group */
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16: andcc %o0, 7, %g0 /* IEU1 */
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be,pn %icc, 1b /* CTI */
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nop /* IEU0 Group */
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add %o0, 1, %o0 /* IEU1 */
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andcc %o3, 0xff, %g0 /* IEU1 Group */
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bne,a,pt %icc, 16b /* CTI */
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lduba [%o0] ASI_PNF, %o3 /* Load */
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add %o0, -1, %o0 /* IEU0 Group */
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retl /* CTI+IEU1 Group */
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sub %o0, %o1, %o0 /* IEU0 */
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END(strlen)
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