| /* |
| * Copyright (c) 2013 RISC OS Open Ltd |
| * Author: Ben Avison <bavison@riscosopen.org> |
| * |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation; either |
| * version 2.1 of the License, or (at your option) any later version. |
| * |
| * FFmpeg is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with FFmpeg; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| #include "libavutil/arm/asm.S" |
| |
| RESULT .req a1 |
| BUF .req a1 |
| SIZE .req a2 |
| PATTERN .req a3 |
| PTR .req a4 |
| DAT0 .req v1 |
| DAT1 .req v2 |
| DAT2 .req v3 |
| DAT3 .req v4 |
| TMP0 .req v5 |
| TMP1 .req v6 |
| TMP2 .req ip |
| TMP3 .req lr |
| |
| #define PRELOAD_DISTANCE 4 |
| |
| .macro innerloop4 |
| ldr DAT0, [PTR], #4 |
| subs SIZE, SIZE, #4 @ C flag survives rest of macro |
| sub TMP0, DAT0, PATTERN, lsr #14 |
| bic TMP0, TMP0, DAT0 |
| ands TMP0, TMP0, PATTERN |
| .endm |
| |
| .macro innerloop16 decrement, do_preload |
| ldmia PTR!, {DAT0,DAT1,DAT2,DAT3} |
| .ifnc "\do_preload","" |
| pld [PTR, #PRELOAD_DISTANCE*32] |
| .endif |
| .ifnc "\decrement","" |
| subs SIZE, SIZE, #\decrement @ C flag survives rest of macro |
| .endif |
| sub TMP0, DAT0, PATTERN, lsr #14 |
| sub TMP1, DAT1, PATTERN, lsr #14 |
| bic TMP0, TMP0, DAT0 |
| bic TMP1, TMP1, DAT1 |
| sub TMP2, DAT2, PATTERN, lsr #14 |
| sub TMP3, DAT3, PATTERN, lsr #14 |
| ands TMP0, TMP0, PATTERN |
| bic TMP2, TMP2, DAT2 |
| it eq |
| andseq TMP1, TMP1, PATTERN |
| bic TMP3, TMP3, DAT3 |
| itt eq |
| andseq TMP2, TMP2, PATTERN |
| andseq TMP3, TMP3, PATTERN |
| .endm |
| |
| /* int ff_startcode_find_candidate_armv6(const uint8_t *buf, int size) */ |
| function ff_startcode_find_candidate_armv6, export=1 |
| push {v1-v6,lr} |
| mov PTR, BUF |
| @ Ensure there are at least (PRELOAD_DISTANCE+2) complete cachelines to go |
| @ before using code that does preloads |
| cmp SIZE, #(PRELOAD_DISTANCE+3)*32 - 1 |
| blo 60f |
| |
| @ Get to word-alignment, 1 byte at a time |
| tst PTR, #3 |
| beq 2f |
| 1: ldrb DAT0, [PTR], #1 |
| sub SIZE, SIZE, #1 |
| teq DAT0, #0 |
| beq 90f |
| tst PTR, #3 |
| bne 1b |
| 2: @ Get to 4-word alignment, 1 word at a time |
| ldr PATTERN, =0x80008000 |
| setend be |
| tst PTR, #12 |
| beq 4f |
| 3: innerloop4 |
| bne 91f |
| tst PTR, #12 |
| bne 3b |
| 4: @ Get to cacheline (8-word) alignment |
| tst PTR, #16 |
| beq 5f |
| innerloop16 16 |
| bne 93f |
| 5: @ Check complete cachelines, with preloading |
| @ We need to stop when there are still (PRELOAD_DISTANCE+1) |
| @ complete cachelines to go |
| sub SIZE, SIZE, #(PRELOAD_DISTANCE+2)*32 |
| 6: innerloop16 , do_preload |
| bne 93f |
| innerloop16 32 |
| bne 93f |
| bcs 6b |
| @ Preload trailing part-cacheline, if any |
| tst SIZE, #31 |
| beq 7f |
| pld [PTR, #(PRELOAD_DISTANCE+1)*32] |
| @ Check remaining data without doing any more preloads. First |
| @ do in chunks of 4 words: |
| 7: adds SIZE, SIZE, #(PRELOAD_DISTANCE+2)*32 - 16 |
| bmi 9f |
| 8: innerloop16 16 |
| bne 93f |
| bcs 8b |
| @ Then in words: |
| 9: adds SIZE, SIZE, #16 - 4 |
| bmi 11f |
| 10: innerloop4 |
| bne 91f |
| bcs 10b |
| 11: setend le |
| @ Check second byte of final halfword |
| ldrb DAT0, [PTR, #-1] |
| teq DAT0, #0 |
| beq 90f |
| @ Check any remaining bytes |
| tst SIZE, #3 |
| beq 13f |
| 12: ldrb DAT0, [PTR], #1 |
| sub SIZE, SIZE, #1 |
| teq DAT0, #0 |
| beq 90f |
| tst SIZE, #3 |
| bne 12b |
| @ No candidate found |
| 13: sub RESULT, PTR, BUF |
| b 99f |
| |
| 60: @ Small buffer - simply check by looping over bytes |
| subs SIZE, SIZE, #1 |
| bcc 99f |
| 61: ldrb DAT0, [PTR], #1 |
| subs SIZE, SIZE, #1 |
| teq DAT0, #0 |
| beq 90f |
| bcs 61b |
| @ No candidate found |
| sub RESULT, PTR, BUF |
| b 99f |
| |
| 90: @ Found a candidate at the preceding byte |
| sub RESULT, PTR, BUF |
| sub RESULT, RESULT, #1 |
| b 99f |
| |
| 91: @ Found a candidate somewhere in the preceding 4 bytes |
| sub RESULT, PTR, BUF |
| sub RESULT, RESULT, #4 |
| sub TMP0, DAT0, #0x20000 |
| bics TMP0, TMP0, DAT0 |
| itt pl |
| ldrbpl DAT0, [PTR, #-3] |
| addpl RESULT, RESULT, #2 |
| bpl 92f |
| teq RESULT, #0 |
| beq 98f @ don't look back a byte if found at first byte in buffer |
| ldrb DAT0, [PTR, #-5] |
| 92: teq DAT0, #0 |
| it eq |
| subeq RESULT, RESULT, #1 |
| b 98f |
| |
| 93: @ Found a candidate somewhere in the preceding 16 bytes |
| sub RESULT, PTR, BUF |
| sub RESULT, RESULT, #16 |
| teq TMP0, #0 |
| beq 95f @ not in first 4 bytes |
| sub TMP0, DAT0, #0x20000 |
| bics TMP0, TMP0, DAT0 |
| itt pl |
| ldrbpl DAT0, [PTR, #-15] |
| addpl RESULT, RESULT, #2 |
| bpl 94f |
| teq RESULT, #0 |
| beq 98f @ don't look back a byte if found at first byte in buffer |
| ldrb DAT0, [PTR, #-17] |
| 94: teq DAT0, #0 |
| it eq |
| subeq RESULT, RESULT, #1 |
| b 98f |
| 95: add RESULT, RESULT, #4 |
| teq TMP1, #0 |
| beq 96f @ not in next 4 bytes |
| sub TMP1, DAT1, #0x20000 |
| bics TMP1, TMP1, DAT1 |
| itee mi |
| ldrbmi DAT0, [PTR, #-13] |
| ldrbpl DAT0, [PTR, #-11] |
| addpl RESULT, RESULT, #2 |
| teq DAT0, #0 |
| it eq |
| subeq RESULT, RESULT, #1 |
| b 98f |
| 96: add RESULT, RESULT, #4 |
| teq TMP2, #0 |
| beq 97f @ not in next 4 bytes |
| sub TMP2, DAT2, #0x20000 |
| bics TMP2, TMP2, DAT2 |
| itee mi |
| ldrbmi DAT0, [PTR, #-9] |
| ldrbpl DAT0, [PTR, #-7] |
| addpl RESULT, RESULT, #2 |
| teq DAT0, #0 |
| it eq |
| subeq RESULT, RESULT, #1 |
| b 98f |
| 97: add RESULT, RESULT, #4 |
| sub TMP3, DAT3, #0x20000 |
| bics TMP3, TMP3, DAT3 |
| itee mi |
| ldrbmi DAT0, [PTR, #-5] |
| ldrbpl DAT0, [PTR, #-3] |
| addpl RESULT, RESULT, #2 |
| teq DAT0, #0 |
| it eq |
| subeq RESULT, RESULT, #1 |
| @ drop through to 98f |
| 98: setend le |
| 99: pop {v1-v6,pc} |
| endfunc |
| |
| .unreq RESULT |
| .unreq BUF |
| .unreq SIZE |
| .unreq PATTERN |
| .unreq PTR |
| .unreq DAT0 |
| .unreq DAT1 |
| .unreq DAT2 |
| .unreq DAT3 |
| .unreq TMP0 |
| .unreq TMP1 |
| .unreq TMP2 |
| .unreq TMP3 |
