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/* memcmp.S
* Copyright (C) 2003, 2005, 2006 Analog Devices Inc., All Rights Reserved.
*
* This file is subject to the terms and conditions of the GNU Library General
* Public License. See the file "COPYING.LIB" in the main directory of this
* archive for more details.
*
* Non-LGPL License also available as part of VisualDSP++
* http://www.analog.com/processors/resources/crosscore/visualDspDevSoftware.html
*/
/* int memcmp(const void *s1, const void *s2, size_t n);
* R0 = First Address (s1)
* R1 = Second Address (s2)
* R2 = count (n)
*
* Favours word aligned data.
*/
#include <features.h>
.text
.align 2
.global _memcmp
.type _memcmp, STT_FUNC
_memcmp:
I1 = P3;
P0 = R0; // P0 = s1 address
P3 = R1; // P3 = s2 Address
P2 = R2 ; // P2 = count
CC = R2 <= 7(IU);
IF CC JUMP too_small;
I0 = R1; // s2
R1 = R1 | R0; // OR addresses together
R1 <<= 30; // check bottom two bits
CC = AZ; // AZ set if zero.
IF !CC JUMP bytes ; // Jump if addrs not aligned.
P1 = P2 >> 2; // count = n/4
R3 = 3;
R2 = R2 & R3; // remainder
P2 = R2; // set remainder
LSETUP (quad_loop_s , quad_loop_e) LC0=P1;
quad_loop_s:
#if !defined(__WORKAROUND_AVOID_DAG1)
MNOP || R0 = [P0++] || R1 = [I0++];
#else
R0 = [P0++];
R1 = [I0++];
#endif
CC = R0 == R1;
IF !CC JUMP quad_different;
quad_loop_e:
NOP;
P3 = I0; // s2
too_small:
CC = P2 == 0; //Check zero count
IF CC JUMP finished; // very unlikely
bytes:
LSETUP (byte_loop_s , byte_loop_e) LC0=P2;
byte_loop_s:
R1 = B[P3++](Z); // *s2
R0 = B[P0++](Z); // *s1
CC = R0 == R1;
IF !CC JUMP different;
byte_loop_e:
NOP;
different:
R0 = R0 - R1;
P3 = I1;
RTS;
quad_different:
// We've read two quads which don't match.
// Can't just compare them, because we're
// a little-endian machine, so the MSBs of
// the regs occur at later addresses in the
// string.
// Arrange to re-read those two quads again,
// byte-by-byte.
P0 += -4; // back up to the start of the
P3 = I0; // quads, and increase the
P2 += 4; // remainder count
P3 += -4;
JUMP bytes;
finished:
R0 = 0;
P3 = I1;
RTS;
.size _memcmp,.-_memcmp
libc_hidden_def (memcmp)
#ifdef __UCLIBC_SUSV3_LEGACY__
strong_alias (memcmp,bcmp)
#endif
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