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ffmpeg / libavcodec / ppc / dsputil_ppc.c @ 2912e87a

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/*
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 * Copyright (c) 2002 Brian Foley
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 * Copyright (c) 2002 Dieter Shirley
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 * Copyright (c) 2003-2004 Romain Dolbeau <romain@dolbeau.org>
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 *
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 * This file is part of Libav.
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 *
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 * Libav 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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 * Libav 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 Libav; 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/cpu.h"
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#include "libavcodec/dsputil.h"
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#include "dsputil_altivec.h"
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/* ***** WARNING ***** WARNING ***** WARNING ***** */
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/*
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clear_blocks_dcbz32_ppc will not work properly on PowerPC processors with a
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cache line size not equal to 32 bytes.
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Fortunately all processor used by Apple up to at least the 7450 (aka second
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generation G4) use 32 bytes cache line.
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This is due to the use of the 'dcbz' instruction. It simply clear to zero a
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single cache line, so you need to know the cache line size to use it !
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It's absurd, but it's fast...
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update 24/06/2003 : Apple released yesterday the G5, with a PPC970. cache line
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size: 128 bytes. Oups.
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The semantic of dcbz was changed, it always clear 32 bytes. so the function
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below will work, but will be slow. So I fixed check_dcbz_effect to use dcbzl,
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which is defined to clear a cache line (as dcbz before). So we still can
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distinguish, and use dcbz (32 bytes) or dcbzl (one cache line) as required.
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see <http://developer.apple.com/technotes/tn/tn2087.html>
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and <http://developer.apple.com/technotes/tn/tn2086.html>
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*/
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static void clear_blocks_dcbz32_ppc(DCTELEM *blocks)
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{
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    register int misal = ((unsigned long)blocks & 0x00000010);
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    register int i = 0;
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#if 1
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    if (misal) {
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        ((unsigned long*)blocks)[0] = 0L;
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        ((unsigned long*)blocks)[1] = 0L;
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        ((unsigned long*)blocks)[2] = 0L;
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        ((unsigned long*)blocks)[3] = 0L;
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        i += 16;
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    }
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    for ( ; i < sizeof(DCTELEM)*6*64-31 ; i += 32) {
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        __asm__ volatile("dcbz %0,%1" : : "b" (blocks), "r" (i) : "memory");
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    }
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    if (misal) {
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        ((unsigned long*)blocks)[188] = 0L;
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        ((unsigned long*)blocks)[189] = 0L;
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        ((unsigned long*)blocks)[190] = 0L;
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        ((unsigned long*)blocks)[191] = 0L;
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        i += 16;
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    }
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#else
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    memset(blocks, 0, sizeof(DCTELEM)*6*64);
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#endif
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}
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/* same as above, when dcbzl clear a whole 128B cache line
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   i.e. the PPC970 aka G5 */
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#if HAVE_DCBZL
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static void clear_blocks_dcbz128_ppc(DCTELEM *blocks)
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{
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    register int misal = ((unsigned long)blocks & 0x0000007f);
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    register int i = 0;
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#if 1
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    if (misal) {
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        // we could probably also optimize this case,
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        // but there's not much point as the machines
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        // aren't available yet (2003-06-26)
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        memset(blocks, 0, sizeof(DCTELEM)*6*64);
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    }
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    else
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        for ( ; i < sizeof(DCTELEM)*6*64 ; i += 128) {
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            __asm__ volatile("dcbzl %0,%1" : : "b" (blocks), "r" (i) : "memory");
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        }
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#else
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    memset(blocks, 0, sizeof(DCTELEM)*6*64);
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#endif
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}
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#else
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static void clear_blocks_dcbz128_ppc(DCTELEM *blocks)
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{
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    memset(blocks, 0, sizeof(DCTELEM)*6*64);
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}
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#endif
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#if HAVE_DCBZL
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/* check dcbz report how many bytes are set to 0 by dcbz */
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/* update 24/06/2003 : replace dcbz by dcbzl to get
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   the intended effect (Apple "fixed" dcbz)
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   unfortunately this cannot be used unless the assembler
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   knows about dcbzl ... */
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static long check_dcbzl_effect(void)
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{
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    register char *fakedata = av_malloc(1024);
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    register char *fakedata_middle;
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    register long zero = 0;
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    register long i = 0;
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    long count = 0;
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    if (!fakedata) {
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        return 0L;
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    }
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    fakedata_middle = (fakedata + 512);
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    memset(fakedata, 0xFF, 1024);
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    /* below the constraint "b" seems to mean "Address base register"
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       in gcc-3.3 / RS/6000 speaks. seems to avoid using r0, so.... */
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    __asm__ volatile("dcbzl %0, %1" : : "b" (fakedata_middle), "r" (zero));
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    for (i = 0; i < 1024 ; i ++) {
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        if (fakedata[i] == (char)0)
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            count++;
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    }
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    av_free(fakedata);
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    return count;
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}
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#else
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static long check_dcbzl_effect(void)
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{
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  return 0;
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}
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#endif
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static void prefetch_ppc(void *mem, int stride, int h)
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{
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    register const uint8_t *p = mem;
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    do {
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        __asm__ volatile ("dcbt 0,%0" : : "r" (p));
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        p+= stride;
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    } while(--h);
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}
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void dsputil_init_ppc(DSPContext* c, AVCodecContext *avctx)
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{
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    // Common optimizations whether AltiVec is available or not
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    c->prefetch = prefetch_ppc;
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    switch (check_dcbzl_effect()) {
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        case 32:
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            c->clear_blocks = clear_blocks_dcbz32_ppc;
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            break;
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        case 128:
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            c->clear_blocks = clear_blocks_dcbz128_ppc;
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            break;
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        default:
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            break;
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    }
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#if HAVE_ALTIVEC
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    if(CONFIG_H264_DECODER) dsputil_h264_init_ppc(c, avctx);
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    if (av_get_cpu_flags() & AV_CPU_FLAG_ALTIVEC) {
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        dsputil_init_altivec(c, avctx);
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        float_init_altivec(c, avctx);
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        int_init_altivec(c, avctx);
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        c->gmc1 = gmc1_altivec;
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#if CONFIG_ENCODERS
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        if (avctx->dct_algo == FF_DCT_AUTO ||
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            avctx->dct_algo == FF_DCT_ALTIVEC) {
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            c->fdct = fdct_altivec;
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        }
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#endif //CONFIG_ENCODERS
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        if (avctx->lowres==0) {
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            if ((avctx->idct_algo == FF_IDCT_AUTO) ||
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                (avctx->idct_algo == FF_IDCT_ALTIVEC)) {
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                c->idct_put = idct_put_altivec;
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                c->idct_add = idct_add_altivec;
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                c->idct_permutation_type = FF_TRANSPOSE_IDCT_PERM;
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            }else if((CONFIG_VP3_DECODER || CONFIG_VP5_DECODER || CONFIG_VP6_DECODER) &&
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                     avctx->idct_algo==FF_IDCT_VP3){
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                c->idct_put = ff_vp3_idct_put_altivec;
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                c->idct_add = ff_vp3_idct_add_altivec;
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                c->idct     = ff_vp3_idct_altivec;
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                c->idct_permutation_type = FF_TRANSPOSE_IDCT_PERM;
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            }
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        }
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    }
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#endif /* HAVE_ALTIVEC */
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}