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	40e6575aa3
	
	
	
		
			
			This is more spec-compliant because it does not rely on dead-code elimination by the compiler. Especially MSVC has problems with this, as can be seen in https://ffmpeg.org/pipermail/ffmpeg-devel/2022-May/296373.html or https://ffmpeg.org/pipermail/ffmpeg-devel/2022-May/297022.html This commit does not eliminate every instance where we rely on dead code elimination: It only tackles branching to the initialization of arch-specific dsp code, not e.g. all uses of CONFIG_ and HAVE_ checks. But maybe it is already enough to compile FFmpeg with MSVC with whole-programm-optimizations enabled (if one does not disable too many components). Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
		
			
				
	
	
		
			114 lines
		
	
	
		
			3.5 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			114 lines
		
	
	
		
			3.5 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
| /*
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|  * Copyright (c) 2011 Mans Rullgard
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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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| 
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| #include "config.h"
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| #include "libavutil/attributes.h"
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| #include "libavutil/thread.h"
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| #include "mpegaudio.h"
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| #include "mpegaudiodsp.h"
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| #include "dct.h"
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| #include "dct32.h"
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| 
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| static AVOnce mpadsp_table_init = AV_ONCE_INIT;
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| 
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| static av_cold void mpadsp_init_tabs(void)
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| {
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|     int i, j;
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|     /* compute mdct windows */
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|     for (i = 0; i < 36; i++) {
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|         for (j = 0; j < 4; j++) {
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|             double d;
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| 
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|             if (j == 2 && i % 3 != 1)
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|                 continue;
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| 
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|             d = sin(M_PI * (i + 0.5) / 36.0);
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|             if (j == 1) {
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|                 if      (i >= 30) d = 0;
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|                 else if (i >= 24) d = sin(M_PI * (i - 18 + 0.5) / 12.0);
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|                 else if (i >= 18) d = 1;
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|             } else if (j == 3) {
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|                 if      (i <   6) d = 0;
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|                 else if (i <  12) d = sin(M_PI * (i -  6 + 0.5) / 12.0);
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|                 else if (i <  18) d = 1;
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|             }
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|             //merge last stage of imdct into the window coefficients
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|             d *= 0.5 * IMDCT_SCALAR / cos(M_PI * (2 * i + 19) / 72);
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| 
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|             if (j == 2) {
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|                 ff_mdct_win_float[j][i/3] = d / (1 << 5);
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|                 ff_mdct_win_fixed[j][i/3] = d / (1 << 5) * (1LL << 32) + 0.5;
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|             } else {
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|                 int idx = i < 18 ? i : i + (MDCT_BUF_SIZE/2 - 18);
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|                 ff_mdct_win_float[j][idx] = d / (1 << 5);
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|                 ff_mdct_win_fixed[j][idx] = d / (1 << 5) * (1LL << 32) + 0.5;
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|             }
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|         }
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|     }
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| 
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|     /* NOTE: we do frequency inversion after the MDCT by changing
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|         the sign of the right window coefs */
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|     for (j = 0; j < 4; j++) {
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|         for (i = 0; i < MDCT_BUF_SIZE; i += 2) {
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|             ff_mdct_win_float[j + 4][i    ] =  ff_mdct_win_float[j][i    ];
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|             ff_mdct_win_float[j + 4][i + 1] = -ff_mdct_win_float[j][i + 1];
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|             ff_mdct_win_fixed[j + 4][i    ] =  ff_mdct_win_fixed[j][i    ];
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|             ff_mdct_win_fixed[j + 4][i + 1] = -ff_mdct_win_fixed[j][i + 1];
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|         }
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|     }
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| 
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| #if ARCH_X86
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|     ff_mpadsp_init_x86_tabs();
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| #endif
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| }
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| 
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| av_cold void ff_mpadsp_init(MPADSPContext *s)
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| {
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|     DCTContext dct;
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| 
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|     ff_dct_init(&dct, 5, DCT_II);
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|     ff_thread_once(&mpadsp_table_init, &mpadsp_init_tabs);
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| 
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|     s->apply_window_float = ff_mpadsp_apply_window_float;
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|     s->apply_window_fixed = ff_mpadsp_apply_window_fixed;
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| 
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|     s->dct32_float = dct.dct32;
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|     s->dct32_fixed = ff_dct32_fixed;
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| 
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|     s->imdct36_blocks_float = ff_imdct36_blocks_float;
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|     s->imdct36_blocks_fixed = ff_imdct36_blocks_fixed;
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| 
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| #if ARCH_AARCH64
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|     ff_mpadsp_init_aarch64(s);
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| #elif ARCH_ARM
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|     ff_mpadsp_init_arm(s);
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| #elif ARCH_PPC
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|     ff_mpadsp_init_ppc(s);
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| #elif ARCH_X86
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|     ff_mpadsp_init_x86(s);
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| #endif
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| #if HAVE_MIPSFPU
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|     ff_mpadsp_init_mipsfpu(s);
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| #endif
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| #if HAVE_MIPSDSP
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|     ff_mpadsp_init_mipsdsp(s);
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| #endif
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| }
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