/* * 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    a1BUF     .req    a1SIZE    .req    a2PATTERN .req    a3PTR     .req    a4DAT0    .req    v1DAT1    .req    v2DAT2    .req    v3DAT3    .req    v4TMP0    .req    v5TMP1    .req    v6TMP2    .req    ipTMP3    .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     2f1:      ldrb    DAT0, [PTR], #1        sub     SIZE, SIZE, #1        teq     DAT0, #0        beq     90f        tst     PTR, #3        bne     1b2:      @ Get to 4-word alignment, 1 word at a time        ldr     PATTERN, =0x80008000        setend  be        tst     PTR, #12        beq     4f3:      innerloop4        bne     91f        tst     PTR, #12        bne     3b4:      @ Get to cacheline (8-word) alignment        tst     PTR, #16        beq     5f        innerloop16  16        bne     93f5:      @ 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)*326:      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     9f8:      innerloop16  16        bne     93f        bcs     8b        @ Then in words:9:      adds    SIZE, SIZE, #16 - 4        bmi     11f10:     innerloop4        bne     91f        bcs     10b11:     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     13f12:     ldrb    DAT0, [PTR], #1        sub     SIZE, SIZE, #1        teq     DAT0, #0        beq     90f        tst     SIZE, #3        bne     12b        @ No candidate found13:     sub     RESULT, PTR, BUF        b       99f 60:     @ Small buffer - simply check by looping over bytes        subs    SIZE, SIZE, #1        bcc     99f61:     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       98f95:     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       98f96:     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       98f97:     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 98f98:     setend  le99:     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