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+/*
+ * File: memcmp.S
+ *
+ * Copyright 2004-2007 Analog Devices Inc.
+ * Enter bugs at http://blackfin.uclinux.org/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see the file COPYING, or write
+ * to the Free Software Foundation, Inc.,
+ * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+.align 2
+
+/*
+ * C Library function MEMCMP
+ * R0 = First Address
+ * R1 = Second Address
+ * R2 = count
+ * Favours word aligned data.
+ */
+
+.globl _memcmp;
+_memcmp:
+ I1 = P3;
+ P0 = R0; /* P0 = s1 address */
+ P3 = R1; /* P3 = s2 Address */
+ P2 = R2 ; /* P2 = count */
+ CC = R2 <= 7(IU);
+ IF CC JUMP .Ltoo_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 .Lbytes ; /* Jump if addrs not aligned. */
+
+ P1 = P2 >> 2; /* count = n/4 */
+ R3 = 3;
+ R2 = R2 & R3; /* remainder */
+ P2 = R2; /* set remainder */
+
+ LSETUP (.Lquad_loop_s , .Lquad_loop_e) LC0=P1;
+.Lquad_loop_s:
+ NOP;
+ R0 = [P0++];
+ R1 = [I0++];
+ CC = R0 == R1;
+ IF !CC JUMP .Lquad_different;
+.Lquad_loop_e:
+ NOP;
+
+ P3 = I0; /* s2 */
+.Ltoo_small:
+ CC = P2 == 0; /* Check zero count*/
+ IF CC JUMP .Lfinished; /* very unlikely*/
+
+.Lbytes:
+ LSETUP (.Lbyte_loop_s , .Lbyte_loop_e) LC0=P2;
+.Lbyte_loop_s:
+ R1 = B[P3++](Z); /* *s2 */
+ R0 = B[P0++](Z); /* *s1 */
+ CC = R0 == R1;
+ IF !CC JUMP .Ldifferent;
+.Lbyte_loop_e:
+ NOP;
+
+.Ldifferent:
+ R0 = R0 - R1;
+ P3 = I1;
+ RTS;
+
+.Lquad_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 .Lbytes;
+
+.Lfinished:
+ R0 = 0;
+ P3 = I1;
+ RTS;