101 lines
2.4 KiB
ArmAsm
101 lines
2.4 KiB
ArmAsm
/*
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* File: memcmp.S
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*
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* Copyright 2004-2007 Analog Devices Inc.
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* Enter bugs at http://blackfin.uclinux.org/
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program 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
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see the file COPYING, or write
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* to the Free Software Foundation, Inc.,
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* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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.align 2
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/*
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* C Library function MEMCMP
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* R0 = First Address
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* R1 = Second Address
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* R2 = count
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* Favours word aligned data.
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*/
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.globl _memcmp;
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_memcmp:
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I1 = P3;
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P0 = R0; /* P0 = s1 address */
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P3 = R1; /* P3 = s2 Address */
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P2 = R2 ; /* P2 = count */
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CC = R2 <= 7(IU);
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IF CC JUMP .Ltoo_small;
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I0 = R1; /* s2 */
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R1 = R1 | R0; /* OR addresses together */
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R1 <<= 30; /* check bottom two bits */
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CC = AZ; /* AZ set if zero. */
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IF !CC JUMP .Lbytes ; /* Jump if addrs not aligned. */
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P1 = P2 >> 2; /* count = n/4 */
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R3 = 3;
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R2 = R2 & R3; /* remainder */
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P2 = R2; /* set remainder */
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LSETUP (.Lquad_loop_s , .Lquad_loop_e) LC0=P1;
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.Lquad_loop_s:
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NOP;
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R0 = [P0++];
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R1 = [I0++];
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CC = R0 == R1;
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IF !CC JUMP .Lquad_different;
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.Lquad_loop_e:
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NOP;
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P3 = I0; /* s2 */
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.Ltoo_small:
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CC = P2 == 0; /* Check zero count*/
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IF CC JUMP .Lfinished; /* very unlikely*/
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.Lbytes:
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LSETUP (.Lbyte_loop_s , .Lbyte_loop_e) LC0=P2;
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.Lbyte_loop_s:
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R1 = B[P3++](Z); /* *s2 */
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R0 = B[P0++](Z); /* *s1 */
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CC = R0 == R1;
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IF !CC JUMP .Ldifferent;
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.Lbyte_loop_e:
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NOP;
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.Ldifferent:
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R0 = R0 - R1;
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P3 = I1;
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RTS;
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.Lquad_different:
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/* We've read two quads which don't match.
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* Can't just compare them, because we're
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* a little-endian machine, so the MSBs of
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* the regs occur at later addresses in the
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* string.
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* Arrange to re-read those two quads again,
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* byte-by-byte.
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*/
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P0 += -4; /* back up to the start of the */
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P3 = I0; /* quads, and increase the*/
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P2 += 4; /* remainder count*/
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P3 += -4;
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JUMP .Lbytes;
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.Lfinished:
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R0 = 0;
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P3 = I1;
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RTS;
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