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94 lines
2.9 KiB
94 lines
2.9 KiB
/* |
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* default memory allocator for libavcodec |
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* Copyright (c) 2002 Fabrice Bellard. |
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* |
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* This library 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 of the License, or (at your option) any later version. |
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* |
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* This library 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 this library; if not, write to the Free Software |
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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*/ |
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#include "avcodec.h" |
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/* here we can use OS dependant allocation functions */ |
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#undef malloc |
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#undef free |
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#undef realloc |
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#ifdef HAVE_MALLOC_H |
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#include <malloc.h> |
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#endif |
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/* you can redefine av_malloc and av_free in your project to use your |
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memory allocator. You do not need to suppress this file because the |
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linker will do it automatically */ |
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/** |
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* Memory allocation of size byte with alignment suitable for all |
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* memory accesses (including vectors if available on the |
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* CPU). av_malloc(0) must return a non NULL pointer. |
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*/ |
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void *av_malloc(unsigned int size) |
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{ |
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void *ptr; |
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#if defined (HAVE_MEMALIGN) |
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ptr = memalign(16,size); |
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/* Why 64? |
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Indeed, we should align it: |
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on 4 for 386 |
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on 16 for 486 |
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on 32 for 586, PPro - k6-III |
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on 64 for K7 (maybe for P3 too). |
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Because L1 and L2 caches are aligned on those values. |
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But I don't want to code such logic here! |
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*/ |
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/* Why 16? |
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because some cpus need alignment, for example SSE2 on P4, & most RISC cpus |
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it will just trigger an exception and the unaligned load will be done in the |
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exception handler or it will just segfault (SSE2 on P4) |
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Why not larger? because i didnt see a difference in benchmarks ... |
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*/ |
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/* benchmarks with p3 |
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memalign(64)+1 3071,3051,3032 |
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memalign(64)+2 3051,3032,3041 |
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memalign(64)+4 2911,2896,2915 |
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memalign(64)+8 2545,2554,2550 |
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memalign(64)+16 2543,2572,2563 |
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memalign(64)+32 2546,2545,2571 |
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memalign(64)+64 2570,2533,2558 |
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btw, malloc seems to do 8 byte alignment by default here |
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*/ |
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#else |
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ptr = malloc(size); |
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#endif |
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return ptr; |
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} |
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/** |
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* av_realloc semantics (same as glibc): if ptr is NULL and size > 0, |
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* identical to malloc(size). If size is zero, it is identical to |
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* free(ptr) and NULL is returned. |
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*/ |
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void *av_realloc(void *ptr, unsigned int size) |
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{ |
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return realloc(ptr, size); |
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} |
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/* NOTE: ptr = NULL is explicetly allowed */ |
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void av_free(void *ptr) |
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{ |
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/* XXX: this test should not be needed on most libcs */ |
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if (ptr) |
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free(ptr); |
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} |
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