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127 lines
3.4 KiB
ArmAsm
127 lines
3.4 KiB
ArmAsm
/*
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* File: arch/blackfin/lib/memcpy.S
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* Based on:
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* Author:
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*
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* Created:
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* Description: internal version of memcpy(), issued by the compiler
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* to copy blocks of data around.
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* This is really memmove() - it has to be able to deal with
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* possible overlaps, because that ambiguity is when the compiler
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* gives up and calls a function. We have our own, internal version
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* so that we get something we trust, even if the user has redefined
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* the normal symbol.
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* Rev: $Id: memcpy.S 2775 2007-02-21 13:58:44Z hennerich $
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*
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* Modified:
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* Copyright 2004-2006 Analog Devices Inc.
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*
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* Bugs: 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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.globl _memcpy_ASM;
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_memcpy_ASM:
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CC = R2 <= 0; /* length not positive?*/
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IF CC JUMP .L_P1L2147483647; /* Nothing to do */
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P0 = R0 ; /* dst*/
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P1 = R1 ; /* src*/
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P2 = R2 ; /* length */
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/* check for overlapping data */
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CC = R1 < R0; /* src < dst */
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IF !CC JUMP .Lno_overlap;
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R3 = R1 + R2;
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CC = R0 < R3; /* and dst < src+len */
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IF CC JUMP .Lhas_overlap;
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.Lno_overlap:
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/* Check for aligned data.*/
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R3 = R1 | R0;
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R0 = 0x3;
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R3 = R3 & R0;
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CC = R3; /* low bits set on either address? */
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IF CC JUMP .Lnot_aligned;
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/* Both addresses are word-aligned, so we can copy
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at least part of the data using word copies.*/
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P2 = P2 >> 2;
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CC = P2 <= 2;
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IF !CC JUMP .Lmore_than_seven;
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/* less than eight bytes... */
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P2 = R2;
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LSETUP(.Lthree_start, .Lthree_end) LC0=P2;
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R0 = R1; /* setup src address for return */
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.Lthree_start:
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R3 = B[P1++] (X);
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.Lthree_end:
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B[P0++] = R3;
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RTS;
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.Lmore_than_seven:
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/* There's at least eight bytes to copy. */
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P2 += -1; /* because we unroll one iteration */
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LSETUP(.Lword_loop, .Lword_loop) LC0=P2;
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R0 = R1;
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I1 = P1;
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R3 = [I1++];
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.Lword_loop:
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MNOP || [P0++] = R3 || R3 = [I1++];
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[P0++] = R3;
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/* Any remaining bytes to copy? */
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R3 = 0x3;
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R3 = R2 & R3;
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CC = R3 == 0;
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P1 = I1; /* in case there's something left, */
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IF !CC JUMP .Lbytes_left;
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RTS;
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.Lbytes_left: P2 = R3;
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.Lnot_aligned:
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/* From here, we're copying byte-by-byte. */
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LSETUP (.Lbyte_start , .Lbyte_end) LC0=P2;
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R0 = R1; /* Save src address for return */
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.Lbyte_start:
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R1 = B[P1++] (X);
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.Lbyte_end:
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B[P0++] = R1;
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.L_P1L2147483647:
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RTS;
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.Lhas_overlap:
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/* Need to reverse the copying, because the
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* dst would clobber the src.
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* Don't bother to work out alignment for
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* the reverse case.
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*/
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R0 = R1; /* save src for later. */
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P0 = P0 + P2;
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P0 += -1;
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P1 = P1 + P2;
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P1 += -1;
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LSETUP(.Lover_start, .Lover_end) LC0=P2;
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.Lover_start:
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R1 = B[P1--] (X);
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.Lover_end:
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B[P0--] = R1;
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RTS;
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