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src/aviwriter/avi_rw_iobuf.cpp
00001 /*
00002  *  Copyright (C) 2018  Jon Campbell
00003  *
00004  *  This program is free software; you can redistribute it and/or modify
00005  *  it under the terms of the GNU General Public License as published by
00006  *  the Free Software Foundation; either version 2 of the License, or
00007  *  (at your option) any later version.
00008  *
00009  *  This program is distributed in the hope that it will be useful,
00010  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
00011  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00012  *  GNU General Public License for more details.
00013  *
00014  *  You should have received a copy of the GNU General Public License
00015  *  along with this program; if not, write to the Free Software
00016  *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
00017  */
00018 
00019 #include <string.h>
00020 #include <stdlib.h>
00021 #include "rawint.h"
00022 #include "avi_rw_iobuf.h"
00023 #include <stdlib.h>
00024 #include <unistd.h>
00025 #include <ctype.h>
00026 
00027 /* common index writing code.
00028  * This code originally wrote the index one struct at a type.
00029  * If you know anything about syscall overhead and disk I/O,
00030  * that's a VERY inefficent way to do it! So index read/write
00031  * code uses our buffer to batch the index entries into RAM
00032  * and write them to disk in one burst */
00033 unsigned char*          avi_io_buf = NULL;
00034 unsigned char*          avi_io_read = NULL;
00035 unsigned char*          avi_io_write = NULL;
00036 unsigned char*          avi_io_fence = NULL;
00037 size_t                  avi_io_elemsize = 0;
00038 size_t                  avi_io_next_adv = 0;
00039 size_t                  avi_io_elemcount = 0;
00040 unsigned char*          avi_io_readfence = NULL;
00041 
00042 unsigned char *avi_io_buffer_init(size_t structsize) {
00043 #define GROUPSIZE ((size_t)(65536*2))
00044         if (avi_io_buf == NULL) {
00045                 avi_io_buf = (unsigned char*)malloc(GROUPSIZE);
00046                 if (avi_io_buf == NULL) return NULL;
00047         }
00048 
00049         avi_io_elemcount = GROUPSIZE / structsize;
00050         avi_io_fence = avi_io_buf + (avi_io_elemcount * structsize);
00051         avi_io_readfence = avi_io_buf;
00052         avi_io_elemsize = structsize;
00053         avi_io_write = avi_io_buf;
00054         avi_io_read = avi_io_buf;
00055         return avi_io_buf;
00056 #undef GROUPSIZE
00057 }
00058 
00059 void avi_io_buffer_free() {
00060         if (avi_io_buf) {
00061                 free(avi_io_buf);
00062                 avi_io_buf = NULL;
00063         }
00064         avi_io_readfence = avi_io_buf;
00065         avi_io_write = avi_io_buf;
00066         avi_io_read = avi_io_buf;
00067 }
00068