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253 lines
7.4 KiB
253 lines
7.4 KiB
/* |
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* Copyright (c) 2013 RISC OS Open Ltd |
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* Author: Ben Avison <bavison@riscosopen.org> |
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* |
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* This file is part of FFmpeg. |
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* |
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* FFmpeg is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* FFmpeg is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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* Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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#include "libavutil/arm/asm.S" |
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RESULT .req a1 |
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BUF .req a1 |
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SIZE .req a2 |
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PATTERN .req a3 |
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PTR .req a4 |
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DAT0 .req v1 |
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DAT1 .req v2 |
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DAT2 .req v3 |
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DAT3 .req v4 |
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TMP0 .req v5 |
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TMP1 .req v6 |
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TMP2 .req ip |
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TMP3 .req lr |
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#define PRELOAD_DISTANCE 4 |
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.macro innerloop4 |
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ldr DAT0, [PTR], #4 |
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subs SIZE, SIZE, #4 @ C flag survives rest of macro |
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sub TMP0, DAT0, PATTERN, lsr #14 |
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bic TMP0, TMP0, DAT0 |
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ands TMP0, TMP0, PATTERN |
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.endm |
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.macro innerloop16 decrement, do_preload |
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ldmia PTR!, {DAT0,DAT1,DAT2,DAT3} |
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.ifnc "\do_preload","" |
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pld [PTR, #PRELOAD_DISTANCE*32] |
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.endif |
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.ifnc "\decrement","" |
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subs SIZE, SIZE, #\decrement @ C flag survives rest of macro |
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.endif |
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sub TMP0, DAT0, PATTERN, lsr #14 |
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sub TMP1, DAT1, PATTERN, lsr #14 |
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bic TMP0, TMP0, DAT0 |
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bic TMP1, TMP1, DAT1 |
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sub TMP2, DAT2, PATTERN, lsr #14 |
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sub TMP3, DAT3, PATTERN, lsr #14 |
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ands TMP0, TMP0, PATTERN |
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bic TMP2, TMP2, DAT2 |
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it eq |
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andseq TMP1, TMP1, PATTERN |
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bic TMP3, TMP3, DAT3 |
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itt eq |
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andseq TMP2, TMP2, PATTERN |
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andseq TMP3, TMP3, PATTERN |
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.endm |
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/* int ff_h264_find_start_code_candidate_armv6(const uint8_t *buf, int size) */ |
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function ff_h264_find_start_code_candidate_armv6, export=1 |
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push {v1-v6,lr} |
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mov PTR, BUF |
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@ Ensure there are at least (PRELOAD_DISTANCE+2) complete cachelines to go |
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@ before using code that does preloads |
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cmp SIZE, #(PRELOAD_DISTANCE+3)*32 - 1 |
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blo 60f |
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@ Get to word-alignment, 1 byte at a time |
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tst PTR, #3 |
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beq 2f |
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1: ldrb DAT0, [PTR], #1 |
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sub SIZE, SIZE, #1 |
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teq DAT0, #0 |
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beq 90f |
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tst PTR, #3 |
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bne 1b |
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2: @ Get to 4-word alignment, 1 word at a time |
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ldr PATTERN, =0x80008000 |
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setend be |
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tst PTR, #12 |
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beq 4f |
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3: innerloop4 |
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bne 91f |
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tst PTR, #12 |
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bne 3b |
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4: @ Get to cacheline (8-word) alignment |
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tst PTR, #16 |
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beq 5f |
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innerloop16 16 |
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bne 93f |
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5: @ Check complete cachelines, with preloading |
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@ We need to stop when there are still (PRELOAD_DISTANCE+1) |
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@ complete cachelines to go |
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sub SIZE, SIZE, #(PRELOAD_DISTANCE+2)*32 |
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6: innerloop16 , do_preload |
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bne 93f |
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innerloop16 32 |
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bne 93f |
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bcs 6b |
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@ Preload trailing part-cacheline, if any |
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tst SIZE, #31 |
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beq 7f |
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pld [PTR, #(PRELOAD_DISTANCE+1)*32] |
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@ Check remaining data without doing any more preloads. First |
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@ do in chunks of 4 words: |
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7: adds SIZE, SIZE, #(PRELOAD_DISTANCE+2)*32 - 16 |
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bmi 9f |
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8: innerloop16 16 |
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bne 93f |
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bcs 8b |
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@ Then in words: |
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9: adds SIZE, SIZE, #16 - 4 |
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bmi 11f |
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10: innerloop4 |
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bne 91f |
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bcs 10b |
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11: setend le |
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@ Check second byte of final halfword |
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ldrb DAT0, [PTR, #-1] |
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teq DAT0, #0 |
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beq 90f |
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@ Check any remaining bytes |
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tst SIZE, #3 |
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beq 13f |
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12: ldrb DAT0, [PTR], #1 |
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sub SIZE, SIZE, #1 |
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teq DAT0, #0 |
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beq 90f |
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tst SIZE, #3 |
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bne 12b |
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@ No candidate found |
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13: sub RESULT, PTR, BUF |
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b 99f |
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60: @ Small buffer - simply check by looping over bytes |
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subs SIZE, SIZE, #1 |
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bcc 99f |
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61: ldrb DAT0, [PTR], #1 |
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subs SIZE, SIZE, #1 |
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teq DAT0, #0 |
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beq 90f |
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bcs 61b |
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@ No candidate found |
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sub RESULT, PTR, BUF |
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b 99f |
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90: @ Found a candidate at the preceding byte |
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sub RESULT, PTR, BUF |
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sub RESULT, RESULT, #1 |
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b 99f |
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91: @ Found a candidate somewhere in the preceding 4 bytes |
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sub RESULT, PTR, BUF |
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sub RESULT, RESULT, #4 |
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sub TMP0, DAT0, #0x20000 |
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bics TMP0, TMP0, DAT0 |
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itt pl |
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ldrbpl DAT0, [PTR, #-3] |
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addpl RESULT, RESULT, #2 |
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bpl 92f |
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teq RESULT, #0 |
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beq 98f @ don't look back a byte if found at first byte in buffer |
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ldrb DAT0, [PTR, #-5] |
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92: teq DAT0, #0 |
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it eq |
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subeq RESULT, RESULT, #1 |
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b 98f |
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93: @ Found a candidate somewhere in the preceding 16 bytes |
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sub RESULT, PTR, BUF |
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sub RESULT, RESULT, #16 |
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teq TMP0, #0 |
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beq 95f @ not in first 4 bytes |
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sub TMP0, DAT0, #0x20000 |
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bics TMP0, TMP0, DAT0 |
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itt pl |
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ldrbpl DAT0, [PTR, #-15] |
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addpl RESULT, RESULT, #2 |
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bpl 94f |
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teq RESULT, #0 |
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beq 98f @ don't look back a byte if found at first byte in buffer |
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ldrb DAT0, [PTR, #-17] |
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94: teq DAT0, #0 |
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it eq |
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subeq RESULT, RESULT, #1 |
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b 98f |
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95: add RESULT, RESULT, #4 |
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teq TMP1, #0 |
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beq 96f @ not in next 4 bytes |
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sub TMP1, DAT1, #0x20000 |
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bics TMP1, TMP1, DAT1 |
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itee mi |
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ldrbmi DAT0, [PTR, #-13] |
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ldrbpl DAT0, [PTR, #-11] |
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addpl RESULT, RESULT, #2 |
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teq DAT0, #0 |
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it eq |
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subeq RESULT, RESULT, #1 |
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b 98f |
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96: add RESULT, RESULT, #4 |
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teq TMP2, #0 |
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beq 97f @ not in next 4 bytes |
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sub TMP2, DAT2, #0x20000 |
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bics TMP2, TMP2, DAT2 |
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itee mi |
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ldrbmi DAT0, [PTR, #-9] |
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ldrbpl DAT0, [PTR, #-7] |
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addpl RESULT, RESULT, #2 |
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teq DAT0, #0 |
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it eq |
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subeq RESULT, RESULT, #1 |
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b 98f |
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97: add RESULT, RESULT, #4 |
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sub TMP3, DAT3, #0x20000 |
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bics TMP3, TMP3, DAT3 |
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itee mi |
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ldrbmi DAT0, [PTR, #-5] |
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ldrbpl DAT0, [PTR, #-3] |
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addpl RESULT, RESULT, #2 |
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teq DAT0, #0 |
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it eq |
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subeq RESULT, RESULT, #1 |
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@ drop through to 98f |
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98: setend le |
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99: pop {v1-v6,pc} |
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.endfunc |
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.unreq RESULT |
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.unreq BUF |
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.unreq SIZE |
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.unreq PATTERN |
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.unreq PTR |
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.unreq DAT0 |
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.unreq DAT1 |
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.unreq DAT2 |
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.unreq DAT3 |
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.unreq TMP0 |
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.unreq TMP1 |
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.unreq TMP2 |
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.unreq TMP3
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