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2d3776b8cc
This fallback function is used if external MMX is available, while inline MMX and intrinsics for emitting emms are unavailable. It is implemented as an avpriv function, which has several drawbacks for shared builds: 1. The function is so small (3 bytes; 16 with padding) that the overhead of exporting and importing it dwarfs the gains from code deduplication. 2. A call to an external library has more overhead than a library-internal one. 3. It may cause linking failures when a libavutil not exporting avpriv_emms_asm() is paired with a library needing it (if inline assembly and intrinsics were unavailable when building the dependent library). I am not aware of this ever happening. 4. We would be forced to keep avpriv_emms_asm() around for ABI stability even after it is no longer needed. This commit therefore uses the STLIBOBJS, SHLIBOBJS approach to duplicating it into each library on its own if needed. Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
102 lines
2.7 KiB
C
102 lines
2.7 KiB
C
/*
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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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#ifndef AVUTIL_EMMS_H
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#define AVUTIL_EMMS_H
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#include <stdint.h>
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#include <stdlib.h>
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#include "config.h"
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#include "libavutil/attributes.h"
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#include "libavutil/log.h"
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#if ARCH_X86
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#if HAVE_MMX_INLINE
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#ifndef __MMX__
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#include "libavutil/cpu.h"
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#endif
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# define emms_c emms_c
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/**
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* Empty mmx state.
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* this must be called between any dsp function and float/double code.
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* for example sin(); dsp->idct_put(); emms_c(); cos()
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* Note, *alloc() and *free() also use float code in some libc implementations
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* thus this also applies to them or any function using them.
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*/
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static av_always_inline void emms_c(void)
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{
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/* Some inlined functions may also use mmx instructions regardless of
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* runtime cpuflags. With that in mind, we unconditionally empty the
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* mmx state if the target cpu chosen at configure time supports it.
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*/
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#if !defined(__MMX__)
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if(av_get_cpu_flags() & AV_CPU_FLAG_MMX)
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#endif
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__asm__ volatile ("emms" ::: "memory");
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}
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static inline void ff_assert0_fpu(const char *file, int line_number)
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{
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uint16_t state[14];
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__asm__ volatile (
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"fstenv %0 \n\t"
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: "+m" (state)
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:
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: "memory"
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);
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if ((state[4] & 3) != 3) {
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emms_c();
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av_log(NULL, AV_LOG_PANIC,
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"Invalid floating point state assertion "
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"triggered at line %u in file %s\n",
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line_number, file);
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abort();
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}
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}
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#define ff_assert0_fpu() ff_assert0_fpu(__FILE__, __LINE__)
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#elif HAVE_MMX && HAVE_MM_EMPTY
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# include <mmintrin.h>
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# define emms_c _mm_empty
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#elif HAVE_MMX_EXTERNAL
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void ff_emms_asm(void);
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# define emms_c ff_emms_asm
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#endif /* HAVE_MMX_INLINE */
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#endif /* ARCH_X86 */
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#ifndef emms_c
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# define emms_c() do {} while(0)
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#endif
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#ifndef ff_assert0_fpu
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#define ff_assert0_fpu() ((void)0)
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#endif
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#if defined(ASSERT_LEVEL) && ASSERT_LEVEL >= 1
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#define ff_assert1_fpu() ff_assert0_fpu()
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#else
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#define ff_assert1_fpu() ((void)0)
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#endif
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#endif /* AVUTIL_EMMS_H */
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