1 files changed, 147 insertions, 0 deletions
diff --git a/MdePkg/Library/BaseMemoryLibOptDxe/Arm/ScanMem.asm b/MdePkg/Library/BaseMemoryLibOptDxe/Arm/ScanMem.asm
new file mode 100644
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+++ b/MdePkg/Library/BaseMemoryLibOptDxe/Arm/ScanMem.asm
@@ -0,0 +1,147 @@
+; Copyright (c) 2010-2011, 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.
+;
+
+
+; 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
+
+; this lets us check a flag in a 00/ff byte easily in either endianness
+#define CHARTSTMASK(c) 1<<(c*8)
+
+    EXPORT  InternalMemScanMem8
+    AREA    ScanMem, CODE, READONLY
+    THUMB
+
+InternalMemScanMem8
+    ; r0 = start of memory to scan
+    ; r1 = length
+    ; r2 = character to look for
+    ; returns r0 = pointer to character or NULL if not found
+    uxtb    r2, r2        ; Don't think we can trust the caller to actually pass a char
+
+    cmp     r1, #16       ; If it's short don't bother with anything clever
+    blt     L20
+
+    tst     r0, #7        ; If it's already aligned skip the next bit
+    beq     L10
+
+    ; Work up to an aligned point
+L5
+    ldrb    r3, [r0],#1
+    subs    r1, r1, #1
+    cmp     r3, r2
+    beq     L50           ; If it matches exit found
+    tst     r0, #7
+    bne     L5            ; If not aligned yet then do next byte
+
+L10
+    ; At this point, we are aligned, we know we have at least 8 bytes to work with
+    push    {r4-r7}
+    orr     r2, r2, r2, lsl #8  ; expand the match word across to all bytes
+    orr     r2, r2, r2, lsl #16
+    bic     r4, r1, #7    ; Number of double words to work with
+    mvns    r7, #0        ; all F's
+    movs    r3, #0
+
+L15
+    ldmia   r0!, {r5,r6}
+    subs    r4, r4, #8
+    eor     r5, r5, r2    ; Get it so that r5,r6 have 00's where the bytes match the target
+    eor     r6, r6, r2
+    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, L60
+    bne     L15           ; (Flags from the subs above) If not run out of bytes then go around again
+
+    pop     {r4-r7}
+    and     r2, r2, #0xff ; Get r2 back to a single character from the expansion above
+    and     r1, r1, #7    ; Leave the count remaining as the number after the double words have been done
+
+L20
+    cbz     r1, L40       ; 0 length or hit the end already then not found
+
+L21 ; Post aligned section, or just a short call
+    ldrb    r3, [r0], #1
+    subs    r1, r1, #1
+    eor     r3, r3, r2    ; r3 = 0 if match - doesn't break flags from sub
+    cbz     r3, L50
+    bne     L21           ; on r1 flags
+
+L40
+    movs    r0, #0        ; not found
+    bx      lr
+
+L50
+    subs    r0, r0, #1    ; found
+    bx      lr
+
+L60 ; 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     L61
+    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
+
+L61
+    pop     {r4-r7}
+    subs    r0, r0, #1
+    bx      lr
+
+    END
+