Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / arch / arc / lib / strcmp.S

diff --git a/kernel/arch/arc/lib/strcmp.S b/kernel/arch/arc/lib/strcmp.S
new file mode 100644 (file)
index 0000000..3544600
--- /dev/null
+++ b/kernel/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 <linux/linkage.h>
+
+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
+END(strcmp)