207 lines
3.9 KiB
ArmAsm
207 lines
3.9 KiB
ArmAsm
// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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#include "go_asm.h"
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#include "textflag.h"
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TEXT ·Index(SB),NOSPLIT,$0-56
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MOVD a_base+0(FP), R0
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MOVD a_len+8(FP), R1
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MOVD b_base+24(FP), R2
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MOVD b_len+32(FP), R3
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MOVD $ret+48(FP), R9
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B indexbody<>(SB)
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TEXT ·IndexString(SB),NOSPLIT,$0-40
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MOVD a_base+0(FP), R0
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MOVD a_len+8(FP), R1
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MOVD b_base+16(FP), R2
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MOVD b_len+24(FP), R3
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MOVD $ret+32(FP), R9
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B indexbody<>(SB)
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// input:
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// R0: haystack
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// R1: length of haystack
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// R2: needle
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// R3: length of needle (2 <= len <= 32)
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// R9: address to put result
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TEXT indexbody<>(SB),NOSPLIT,$0-56
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// main idea is to load 'sep' into separate register(s)
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// to avoid repeatedly re-load it again and again
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// for sebsequent substring comparisons
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SUB R3, R1, R4
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// R4 contains the start of last substring for comparison
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ADD R0, R4, R4
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ADD $1, R0, R8
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CMP $8, R3
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BHI greater_8
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TBZ $3, R3, len_2_7
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len_8:
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// R5 contains 8-byte of sep
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MOVD (R2), R5
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loop_8:
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// R6 contains substring for comparison
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CMP R4, R0
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BHI not_found
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MOVD.P 1(R0), R6
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CMP R5, R6
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BNE loop_8
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B found
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len_2_7:
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TBZ $2, R3, len_2_3
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TBZ $1, R3, len_4_5
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TBZ $0, R3, len_6
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len_7:
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// R5 and R6 contain 7-byte of sep
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MOVWU (R2), R5
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// 1-byte overlap with R5
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MOVWU 3(R2), R6
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loop_7:
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CMP R4, R0
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BHI not_found
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MOVWU.P 1(R0), R3
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CMP R5, R3
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BNE loop_7
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MOVWU 2(R0), R3
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CMP R6, R3
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BNE loop_7
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B found
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len_6:
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// R5 and R6 contain 6-byte of sep
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MOVWU (R2), R5
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MOVHU 4(R2), R6
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loop_6:
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CMP R4, R0
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BHI not_found
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MOVWU.P 1(R0), R3
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CMP R5, R3
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BNE loop_6
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MOVHU 3(R0), R3
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CMP R6, R3
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BNE loop_6
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B found
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len_4_5:
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TBZ $0, R3, len_4
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len_5:
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// R5 and R7 contain 5-byte of sep
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MOVWU (R2), R5
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MOVBU 4(R2), R7
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loop_5:
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CMP R4, R0
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BHI not_found
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MOVWU.P 1(R0), R3
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CMP R5, R3
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BNE loop_5
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MOVBU 3(R0), R3
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CMP R7, R3
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BNE loop_5
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B found
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len_4:
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// R5 contains 4-byte of sep
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MOVWU (R2), R5
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loop_4:
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CMP R4, R0
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BHI not_found
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MOVWU.P 1(R0), R6
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CMP R5, R6
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BNE loop_4
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B found
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len_2_3:
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TBZ $0, R3, len_2
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len_3:
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// R6 and R7 contain 3-byte of sep
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MOVHU (R2), R6
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MOVBU 2(R2), R7
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loop_3:
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CMP R4, R0
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BHI not_found
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MOVHU.P 1(R0), R3
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CMP R6, R3
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BNE loop_3
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MOVBU 1(R0), R3
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CMP R7, R3
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BNE loop_3
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B found
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len_2:
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// R5 contains 2-byte of sep
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MOVHU (R2), R5
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loop_2:
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CMP R4, R0
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BHI not_found
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MOVHU.P 1(R0), R6
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CMP R5, R6
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BNE loop_2
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found:
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SUB R8, R0, R0
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MOVD R0, (R9)
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RET
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not_found:
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MOVD $-1, R0
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MOVD R0, (R9)
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RET
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greater_8:
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SUB $9, R3, R11 // len(sep) - 9, offset of R0 for last 8 bytes
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CMP $16, R3
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BHI greater_16
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len_9_16:
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MOVD.P 8(R2), R5 // R5 contains the first 8-byte of sep
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SUB $16, R3, R7 // len(sep) - 16, offset of R2 for last 8 bytes
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MOVD (R2)(R7), R6 // R6 contains the last 8-byte of sep
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loop_9_16:
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// search the first 8 bytes first
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CMP R4, R0
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BHI not_found
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MOVD.P 1(R0), R7
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CMP R5, R7
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BNE loop_9_16
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MOVD (R0)(R11), R7
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CMP R6, R7 // compare the last 8 bytes
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BNE loop_9_16
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B found
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greater_16:
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CMP $24, R3
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BHI len_25_32
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len_17_24:
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LDP.P 16(R2), (R5, R6) // R5 and R6 contain the first 16-byte of sep
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SUB $24, R3, R10 // len(sep) - 24
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MOVD (R2)(R10), R7 // R7 contains the last 8-byte of sep
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loop_17_24:
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// search the first 16 bytes first
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CMP R4, R0
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BHI not_found
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MOVD.P 1(R0), R10
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CMP R5, R10
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BNE loop_17_24
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MOVD 7(R0), R10
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CMP R6, R10
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BNE loop_17_24
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MOVD (R0)(R11), R10
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CMP R7, R10 // compare the last 8 bytes
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BNE loop_17_24
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B found
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len_25_32:
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LDP.P 16(R2), (R5, R6)
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MOVD.P 8(R2), R7 // R5, R6 and R7 contain the first 24-byte of sep
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SUB $32, R3, R12 // len(sep) - 32
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MOVD (R2)(R12), R10 // R10 contains the last 8-byte of sep
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loop_25_32:
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// search the first 24 bytes first
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CMP R4, R0
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BHI not_found
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MOVD.P 1(R0), R12
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CMP R5, R12
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BNE loop_25_32
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MOVD 7(R0), R12
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CMP R6, R12
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BNE loop_25_32
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MOVD 15(R0), R12
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CMP R7, R12
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BNE loop_25_32
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MOVD (R0)(R11), R12
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CMP R10, R12 // compare the last 8 bytes
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BNE loop_25_32
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B found
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