matOut/writeEmptyArray.c at master · EyNuel/matOut · GitHub

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/*
 *  Copyright 2011 Emanuel Ey <[email protected]>
 *
 *  This file is part of matOut.
 *
 *  MatOut is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Lesser General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  MatOut 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 Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with matOut.  If not, see <http://www.gnu.org/licenses/>.
 */

#pragma once
#include <stdio.h>
#include <stdint.h>
#include "matOut.h"

/*
 * Writes an empty mxArray to file.
 * This is required when structures contain empty fields.
 * The structures fields must always exist, even if empty.
 */

void writeEmptyArray(FILE* outfile);

void writeEmptyArray(FILE* outfile){
    /*
     * TODO: documentation
     * TODO: verify successfull write
     */
    uint32_t    nBytes, tempUInt32, flags, mxClass;
    size_t      discard;

    //char marker[8] = {'X','X','X','X','X','X','X','X'};
    //fwrite(&marker, sizeof(uint8_t), 8, outfile);

    /*
     * Size required by an empty mxArray:
     */
    /*
     *  nBytes += 8;    //header:                       "miMatrix"[4B]; "size"[4B]
     *  nBytes += 16;   //Array flags:                  "miUINT32"[4B]; "8"[4B]; "flags+mxCLASS"[4B]; "undefined"[4B]
     *  nBytes += 16;   //2D dimensions (1x1)
     *  nBytes += 8;    //empty array name              "miINT8"[4B]; "0"[4B]
     *  nBytes += 8;    //empty "double" data element   "miDouble"[4B9; "0"[4B]
     *  NOTE: size written to header does not include the 8B required for the header itself;
     */
    nBytes = 48;

    //write header:
    tempUInt32  = miMATRIX;
    discard = fwrite(&tempUInt32, sizeof(uint32_t), 1, outfile); (void)discard;
    discard = fwrite(&nBytes, sizeof(uint32_t), 1, outfile); (void)discard;


    //write array flags:
    tempUInt32  = miUINT32;
    discard = fwrite(&tempUInt32, sizeof(uint32_t), 1, outfile); (void)discard;
    tempUInt32  = 8;
    discard = fwrite(&tempUInt32, sizeof(uint32_t), 1, outfile); (void)discard;

    //NOTE: for the purpose of writing and empty array, we'll define it as "real" and "double"
    flags       =   0x00;
    mxClass     =   mxDOUBLE_CLASS;

    tempUInt32  =   flags;
    tempUInt32  <<= 8;  //left shift the flags by one byte
    tempUInt32  |=  mxClass;
    discard = fwrite(&tempUInt32, sizeof(uint32_t), 1, outfile); (void)discard;
    tempUInt32  =   0x00;
    discard = fwrite(&tempUInt32, sizeof(uint32_t), 1, outfile); (void)discard;


    //write dimensions array (size is 1x1):
    tempUInt32  = miINT32;
    discard = fwrite(&tempUInt32, sizeof(uint32_t), 1, outfile); (void)discard;
    tempUInt32  = 8;
    discard = fwrite(&tempUInt32, sizeof(uint32_t), 1, outfile); (void)discard;
    tempUInt32  = 1;
    discard = fwrite(&tempUInt32, sizeof(uint32_t), 1, outfile); (void)discard;
    discard = fwrite(&tempUInt32, sizeof(uint32_t), 1, outfile); (void)discard;


    //write an empty name:
    tempUInt32  = miINT8;
    discard = fwrite(&tempUInt32, sizeof(uint32_t), 1, outfile); (void)discard;
    tempUInt32  = 0;
    discard = fwrite(&tempUInt32, sizeof(uint32_t), 1, outfile); (void)discard;


    //write mxClass (double) and size (which is zero):
    tempUInt32  = miDOUBLE;
    discard = fwrite(&tempUInt32, sizeof(uint32_t), 1, outfile); (void)discard;
    tempUInt32  = 0;
    discard = fwrite(&tempUInt32, sizeof(uint32_t), 1, outfile); (void)discard;

    //fwrite(&marker, sizeof(uint8_t), 8, outfile);

}