logmemfile.c

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/*
 *       Cineon image file format library routines.
 *
 *       Copyright 2006 Joseph Eagar (joeedh@gmail.com)
 *
 *       This program is free software; you can redistribute it and/or modify it
 *       under the terms of the GNU General Public License as published by the Free
 *       Software Foundation; either version 2 of the License, or (at your option)
 *       any later version.
 *
 *       This program is distributed in the hope that it will be useful, but
 *       WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 *       or FITNESS FOR A PARTICULAR PURPOSE.    See the GNU General Public License
 *       for more details.
 *
 *       You should have received a copy of the GNU General Public License
 *       along with this program; if not, write to the Free Software
 *       Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "logImageCore.h"

#include "logmemfile.h" /* own include */

int logimage_fseek(void* logfile, intptr_t offsett, int origin)
{       
        struct _Log_Image_File_t_ *file = (struct _Log_Image_File_t_*) logfile;
        intptr_t offset = offsett;
        
        if (file->file) fseek(file->file, offset, origin);
        else { /*we're seeking in memory*/
                if (origin==SEEK_SET) {
                        if (offset > file->membuffersize) return 1;
                        file->memcursor = file->membuffer + offset;
                } else if (origin==SEEK_END) {
                        if (offset > file->membuffersize) return 1;
                        file->memcursor = (file->membuffer + file->membuffersize) - offset;
                } else if (origin==SEEK_CUR) {
                        uintptr_t pos = (uintptr_t)file->membuffer - (uintptr_t)file->memcursor;
                        if (pos + offset > file->membuffersize) return 1;
                        if (pos < 0) return 1;
                        file->memcursor += offset;
                }
        }
        return 0;
}

int logimage_fwrite(void *buffer, unsigned int size, unsigned int count, void *logfile)
{
        struct _Log_Image_File_t_ *file = (struct _Log_Image_File_t_*) logfile;
        if (file->file) return fwrite(buffer, size, count, file->file);
        else { /*we're writing to memory*/
                /*do nothing as this isn't supported yet*/
                return count;
        }
}

int logimage_fread(void *buffer, unsigned int size, unsigned int count, void *logfile)
{
        struct _Log_Image_File_t_ *file = (struct _Log_Image_File_t_*) logfile;
        if (file->file) return fread(buffer, size, count, file->file);
        else { /*we're reading from memory*/
                int i;
                /*we convert ot uchar just on the off chance some platform can't handle
                  pointer arithmetic with type (void*). */
                unsigned char *buf = (unsigned char *) buffer; 
                
                for (i=0; i<count; i++) {
                        memcpy(buf, file->memcursor, size);
                        file->memcursor += size;
                        buf += size;
                }
                return count;
        }
}