--- /dev/null
+/* Copyright (c) 2010-2015, Linaro Limited
+ All rights reserved.
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions
+ are met:
+
+ * Redistributions of source code must retain the above copyright
+ notice, this list of conditions and the following disclaimer.
+
+ * Redistributions in binary form must reproduce the above copyright
+ notice, this list of conditions and the following disclaimer in the
+ documentation and/or other materials provided with the distribution.
+
+ * Neither the name of Linaro Limited nor the names of its
+ contributors may be used to endorse or promote products derived
+ from this software without specific prior written permission.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+ Written by Dave Gilbert <david.gilbert@linaro.org>
+
+ This memchr routine is optimised on a Cortex-A9 and should work on
+ all ARMv7 processors. It has a fast past for short sizes, and has
+ an optimised path for large data sets; the worst case is finding the
+ match early in a large data set.
+
+ */
+
+#include <private/bionic_asm.h>
+
+@ 2011-02-07 david.gilbert@linaro.org
+@ Extracted from local git a5b438d861
+@ 2011-07-14 david.gilbert@linaro.org
+@ Import endianness fix from local git ea786f1b
+@ 2011-12-07 david.gilbert@linaro.org
+@ Removed unneeded cbz from align loop
+
+ .syntax unified
+ .arch armv7-a
+
+@ this lets us check a flag in a 00/ff byte easily in either endianness
+#ifdef __ARMEB__
+#define CHARTSTMASK(c) 1<<(31-(c*8))
+#else
+#define CHARTSTMASK(c) 1<<(c*8)
+#endif
+ .text
+ .thumb
+
+@ ---------------------------------------------------------------------------
+ .thumb_func
+ENTRY(memchr)
+ .p2align 4,,15
+ @ r0 = start of memory to scan
+ @ r1 = character to look for
+ @ r2 = length
+ @ returns r0 = pointer to character or NULL if not found
+ and r1,r1,#0xff @ Don't think we can trust the caller to actually pass a char
+
+ cmp r2,#16 @ If it's short don't bother with anything clever
+ blt 20f
+
+ tst r0, #7 @ If it's already aligned skip the next bit
+ beq 10f
+
+ @ Work up to an aligned point
+5:
+ ldrb r3, [r0],#1
+ subs r2, r2, #1
+ cmp r3, r1
+ beq 50f @ If it matches exit found
+ tst r0, #7
+ bne 5b @ If not aligned yet then do next byte
+
+10:
+ @ At this point, we are aligned, we know we have at least 8 bytes to work with
+ push {r4,r5,r6,r7}
+ orr r1, r1, r1, lsl #8 @ expand the match word across to all bytes
+ orr r1, r1, r1, lsl #16
+ bic r4, r2, #7 @ Number of double words to work with
+ mvns r7, #0 @ all F's
+ movs r3, #0
+
+15:
+ ldrd r5,r6,[r0],#8
+ subs r4, r4, #8
+ eor r5,r5, r1 @ Get it so that r5,r6 have 00's where the bytes match the target
+ eor r6,r6, r1
+ uadd8 r5, r5, r7 @ Parallel add 0xff - sets the GE bits for anything that wasn't 0
+ sel r5, r3, r7 @ bytes are 00 for none-00 bytes, or ff for 00 bytes - NOTE INVERSION
+ uadd8 r6, r6, r7 @ Parallel add 0xff - sets the GE bits for anything that wasn't 0
+ sel r6, r5, r7 @ chained....bytes are 00 for none-00 bytes, or ff for 00 bytes - NOTE INVERSION
+ cbnz r6, 60f
+ bne 15b @ (Flags from the subs above) If not run out of bytes then go around again
+
+ pop {r4,r5,r6,r7}
+ and r1,r1,#0xff @ Get r1 back to a single character from the expansion above
+ and r2,r2,#7 @ Leave the count remaining as the number after the double words have been done
+
+20:
+ cbz r2, 40f @ 0 length or hit the end already then not found
+
+21: @ Post aligned section, or just a short call
+ ldrb r3,[r0],#1
+ subs r2,r2,#1
+ eor r3,r3,r1 @ r3 = 0 if match - doesn't break flags from sub
+ cbz r3, 50f
+ bne 21b @ on r2 flags
+
+40:
+ movs r0,#0 @ not found
+ bx lr
+
+50:
+ subs r0,r0,#1 @ found
+ bx lr
+
+60: @ We're here because the fast path found a hit - now we have to track down exactly which word it was
+ @ r0 points to the start of the double word after the one that was tested
+ @ r5 has the 00/ff pattern for the first word, r6 has the chained value
+ cmp r5, #0
+ itte eq
+ moveq r5, r6 @ the end is in the 2nd word
+ subeq r0,r0,#3 @ Points to 2nd byte of 2nd word
+ subne r0,r0,#7 @ or 2nd byte of 1st word
+
+ @ r0 currently points to the 3rd byte of the word containing the hit
+ tst r5, # CHARTSTMASK(0) @ 1st character
+ bne 61f
+ adds r0,r0,#1
+ tst r5, # CHARTSTMASK(1) @ 2nd character
+ ittt eq
+ addeq r0,r0,#1
+ tsteq r5, # (3<<15) @ 2nd & 3rd character
+ @ If not the 3rd must be the last one
+ addeq r0,r0,#1
+
+61:
+ pop {r4,r5,r6,r7}
+ subs r0,r0,#1
+ bx lr
+END(memchr)
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