• Main Page
  • Related Pages
  • Modules
  • Data Structures
  • Files
  • File List
  • Globals

libavcodec/alpha/mpegvideo_alpha.c

Go to the documentation of this file.
00001 /*
00002  * Alpha optimized DSP utils
00003  * Copyright (c) 2002 Falk Hueffner <falk@debian.org>
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00022 #include "libavcodec/dsputil.h"
00023 #include "libavcodec/mpegvideo.h"
00024 #include "asm.h"
00025 
00026 static void dct_unquantize_h263_axp(DCTELEM *block, int n_coeffs,
00027                                     uint64_t qscale, uint64_t qadd)
00028 {
00029     uint64_t qmul = qscale << 1;
00030     uint64_t correction = WORD_VEC(qmul * 255 >> 8);
00031     int i;
00032 
00033     qadd = WORD_VEC(qadd);
00034 
00035     for(i = 0; i <= n_coeffs; block += 4, i += 4) {
00036         uint64_t levels, negmask, zeros, add, sub;
00037 
00038         levels = ldq(block);
00039         if (levels == 0)
00040             continue;
00041 
00042 #ifdef __alpha_max__
00043         /* I don't think the speed difference justifies runtime
00044            detection.  */
00045         negmask = maxsw4(levels, -1); /* negative -> ffff (-1) */
00046         negmask = minsw4(negmask, 0); /* positive -> 0000 (0) */
00047 #else
00048         negmask = cmpbge(WORD_VEC(0x7fff), levels);
00049         negmask &= (negmask >> 1) | (1 << 7);
00050         negmask = zap(-1, negmask);
00051 #endif
00052 
00053         zeros = cmpbge(0, levels);
00054         zeros &= zeros >> 1;
00055         /* zeros |= zeros << 1 is not needed since qadd <= 255, so
00056            zapping the lower byte suffices.  */
00057 
00058         levels *= qmul;
00059         levels -= correction & (negmask << 16);
00060 
00061         add = qadd & ~negmask;
00062         sub = qadd &  negmask;
00063         /* Set qadd to 0 for levels == 0.  */
00064         add = zap(add, zeros);
00065         levels += add;
00066         levels -= sub;
00067 
00068         stq(levels, block);
00069     }
00070 }
00071 
00072 static void dct_unquantize_h263_intra_axp(MpegEncContext *s, DCTELEM *block,
00073                                     int n, int qscale)
00074 {
00075     int n_coeffs;
00076     uint64_t qadd;
00077     DCTELEM block0 = block[0];
00078 
00079     if (!s->h263_aic) {
00080         if (n < 4)
00081             block0 *= s->y_dc_scale;
00082         else
00083             block0 *= s->c_dc_scale;
00084         qadd = (qscale - 1) | 1;
00085     } else {
00086         qadd = 0;
00087     }
00088 
00089     if(s->ac_pred)
00090         n_coeffs = 63;
00091     else
00092         n_coeffs = s->inter_scantable.raster_end[s->block_last_index[n]];
00093 
00094     dct_unquantize_h263_axp(block, n_coeffs, qscale, qadd);
00095 
00096     block[0] = block0;
00097 }
00098 
00099 static void dct_unquantize_h263_inter_axp(MpegEncContext *s, DCTELEM *block,
00100                                     int n, int qscale)
00101 {
00102     int n_coeffs = s->inter_scantable.raster_end[s->block_last_index[n]];
00103     dct_unquantize_h263_axp(block, n_coeffs, qscale, (qscale - 1) | 1);
00104 }
00105 
00106 void MPV_common_init_axp(MpegEncContext *s)
00107 {
00108     s->dct_unquantize_h263_intra = dct_unquantize_h263_intra_axp;
00109     s->dct_unquantize_h263_inter = dct_unquantize_h263_inter_axp;
00110 }

Generated on Fri Sep 16 2011 17:17:33 for FFmpeg by  doxygen 1.7.1