1 files changed, 96 insertions, 0 deletions

diff --git a/arch/arc/lib/strcmp.S b/arch/arc/lib/strcmp.S
new file mode 100644
index 000000000000..5dc802b45cf3
--- /dev/null
+++ b/arch/arc/lib/strcmp.S
@@ -0,0 +1,96 @@
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+/* This is optimized primarily for the ARC700.
+   It would be possible to speed up the loops by one cycle / word
+   respective one cycle / byte by forcing double source 1 alignment, unrolling
+   by a factor of two, and speculatively loading the second word / byte of
+   source 1; however, that would increase the overhead for loop setup / finish,
+   and strcmp might often terminate early.  */
+
+#include <asm/linkage.h>
+
+ARC_ENTRY strcmp
+        or      r2,r0,r1
+        bmsk_s  r2,r2,1
+        brne    r2,0,.Lcharloop
+        mov_s   r12,0x01010101
+        ror     r5,r12
+.Lwordloop:
+        ld.ab   r2,[r0,4]
+        ld.ab   r3,[r1,4]
+        nop_s
+        sub     r4,r2,r12
+        bic     r4,r4,r2
+        and     r4,r4,r5
+        brne    r4,0,.Lfound0
+        breq    r2,r3,.Lwordloop
+#ifdef  __LITTLE_ENDIAN__
+        xor     r0,r2,r3        ; mask for difference
+        sub_s   r1,r0,1
+        bic_s   r0,r0,r1        ; mask for least significant difference bit
+        sub     r1,r5,r0
+        xor     r0,r5,r1        ; mask for least significant difference byte
+        and_s   r2,r2,r0
+        and_s   r3,r3,r0
+#endif /* LITTLE ENDIAN */
+        cmp_s   r2,r3
+        mov_s   r0,1
+        j_s.d   [blink]
+        bset.lo r0,r0,31
+
+        .balign 4
+#ifdef __LITTLE_ENDIAN__
+.Lfound0:
+        xor     r0,r2,r3        ; mask for difference
+        or      r0,r0,r4        ; or in zero indicator
+        sub_s   r1,r0,1
+        bic_s   r0,r0,r1        ; mask for least significant difference bit
+        sub     r1,r5,r0
+        xor     r0,r5,r1        ; mask for least significant difference byte
+        and_s   r2,r2,r0
+        and_s   r3,r3,r0
+        sub.f   r0,r2,r3
+        mov.hi  r0,1
+        j_s.d   [blink]
+        bset.lo r0,r0,31
+#else /* BIG ENDIAN */
+        /* The zero-detection above can mis-detect 0x01 bytes as zeroes
+           because of carry-propagateion from a lower significant zero byte.
+           We can compensate for this by checking that bit0 is zero.
+           This compensation is not necessary in the step where we
+           get a low estimate for r2, because in any affected bytes
+           we already have 0x00 or 0x01, which will remain unchanged
+           when bit 7 is cleared.  */
+        .balign 4
+.Lfound0:
+        lsr     r0,r4,8
+        lsr_s   r1,r2
+        bic_s   r2,r2,r0        ; get low estimate for r2 and get ...
+        bic_s   r0,r0,r1        ; <this is the adjusted mask for zeros>
+        or_s    r3,r3,r0        ; ... high estimate r3 so that r2 > r3 will ...
+        cmp_s   r3,r2           ; ... be independent of trailing garbage
+        or_s    r2,r2,r0        ; likewise for r3 > r2
+        bic_s   r3,r3,r0
+        rlc     r0,0            ; r0 := r2 > r3 ? 1 : 0
+        cmp_s   r2,r3
+        j_s.d   [blink]
+        bset.lo r0,r0,31
+#endif /* ENDIAN */
+
+        .balign 4
+.Lcharloop:
+        ldb.ab  r2,[r0,1]
+        ldb.ab  r3,[r1,1]
+        nop_s
+        breq    r2,0,.Lcmpend
+        breq    r2,r3,.Lcharloop
+.Lcmpend:
+        j_s.d   [blink]
+        sub     r0,r2,r3
+ARC_EXIT strcmp