/* 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