cstraw.cpp

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/*
**  Command & Conquer Generals Zero Hour(tm)
**  Copyright 2025 Electronic Arts Inc.
**
**  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 3 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, see <http://www.gnu.org/licenses/>.
*/
 
/*********************************************************************************************** 
 ***              C O N F I D E N T I A L  ---  W E S T W O O D  S T U D I O S               *** 
 *********************************************************************************************** 
 *                                                                                             * 
 *                 Project Name : Command & Conquer                                            * 
 *                                                                                             * 
 *                     $Archive:: /Commando/Library/CSTRAW.CPP                                $* 
 *                                                                                             * 
 *                      $Author:: Greg_h                                                      $*
 *                                                                                             * 
 *                     $Modtime:: 7/22/97 11:37a                                              $*
 *                                                                                             * 
 *                    $Revision:: 1                                                           $*
 *                                                                                             *
 *---------------------------------------------------------------------------------------------* 
 * Functions:                                                                                  * 
 *   CacheStraw::Get -- Fetch data from the data source.                                       *
 * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 
#include    "always.h"
#include    "cstraw.h"
#include    <string.h>
 
 
/***********************************************************************************************
 * CacheStraw::Get -- Fetch data from the data source.                                         *
 *                                                                                             *
 *    This will supply the data quantity requested. It performs a regulating influence on the  *
 *    data requests passed through it. The data is requested from the next straw in the        *
 *    chain such that the data stream is requested in chunks. This serves to lessen the        *
 *    impact of multiple small data requests.                                                  *
 *                                                                                             *
 * INPUT:   source   -- Pointer to the buffer to hold the data.                                *
 *                                                                                             *
 *          slen     -- The number of data bytes requested.                                    *
 *                                                                                             *
 * OUTPUT:  Returns with the number of data bytes stored into the buffer specified. If this    *
 *          number is less than that requested, it indicates that the data source has been     *
 *          exhausted.                                                                         *
 *                                                                                             *
 * WARNINGS:   none                                                                            *
 *                                                                                             *
 * HISTORY:                                                                                    *
 *   11/10/1996 JLB : Created.                                                                 *
 *=============================================================================================*/
int CacheStraw::Get(void * source, int slen)
{
    int total = 0;
 
    if (Is_Valid() && source != NULL && slen > 0) {
 
        /*
        **  Keep processing the data request until there is no more data to supply or the request
        **  has been fulfilled.
        */
        while (slen > 0) {
 
            /*
            **  First try to fetch the data from data previously loaded into the buffer.
            */
            if (Length > 0) {
                int tocopy = (Length < slen) ? Length : slen;
                memmove(source, ((char *)BufferPtr.Get_Buffer()) + Index, tocopy);
                slen -= tocopy;
                Index += tocopy;
                total += tocopy;
                Length -= tocopy;
                source = (char*)source + tocopy;
            }
            if (slen == 0) break;
 
            /*
            **  Since there is more to be fulfilled yet the holding buffer is empty,
            **  refill the buffer with a fresh block of data from the source.
            */
            Length = Straw::Get(BufferPtr, BufferPtr.Get_Size());
            Index = 0;
            if (Length == 0) break;
        }
    }
    return(total);
}