94 lines
2.4 KiB
ArmAsm
94 lines
2.4 KiB
ArmAsm
/*
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* File: memset.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 MEMSET
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* R0 = address (leave unchanged to form result)
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* R1 = filler byte
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* R2 = count
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* Favours word aligned data.
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*/
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.globl _memset;
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_memset:
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P0 = R0 ; /* P0 = address */
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P2 = R2 ; /* P2 = count */
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R3 = R0 + R2; /* end */
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CC = R2 <= 7(IU);
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IF CC JUMP .Ltoo_small;
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R1 = R1.B (Z); /* R1 = fill char */
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R2 = 3;
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R2 = R0 & R2; /* addr bottom two bits */
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CC = R2 == 0; /* AZ set if zero. */
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IF !CC JUMP .Lforce_align ; /* Jump if addr not aligned. */
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.Laligned:
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P1 = P2 >> 2; /* count = n/4 */
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R2 = R1 << 8; /* create quad filler */
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R2.L = R2.L + R1.L(NS);
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R2.H = R2.L + R1.H(NS);
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P2 = R3;
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LSETUP (.Lquad_loop , .Lquad_loop) LC0=P1;
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.Lquad_loop:
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[P0++] = R2;
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CC = P0 == P2;
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IF !CC JUMP .Lbytes_left;
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RTS;
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.Lbytes_left:
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R2 = R3; /* end point */
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R3 = P0; /* current position */
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R2 = R2 - R3; /* bytes left */
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P2 = R2;
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.Ltoo_small:
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CC = P2 == 0; /* Check zero count */
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IF CC JUMP .Lfinished; /* Unusual */
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.Lbytes:
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LSETUP (.Lbyte_loop , .Lbyte_loop) LC0=P2;
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.Lbyte_loop:
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B[P0++] = R1;
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.Lfinished:
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RTS;
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.Lforce_align:
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CC = BITTST (R0, 0); /* odd byte */
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R0 = 4;
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R0 = R0 - R2;
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P1 = R0;
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R0 = P0; /* Recover return address */
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IF !CC JUMP .Lskip1;
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B[P0++] = R1;
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.Lskip1:
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CC = R2 <= 2; /* 2 bytes */
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P2 -= P1; /* reduce count */
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IF !CC JUMP .Laligned;
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B[P0++] = R1;
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B[P0++] = R1;
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JUMP .Laligned;
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