/*
 *
 * UNICON - The Console Chinese & I18N
 * Copyright (c) 1999-2002
 *
 * This file is part of UNICON, a console Chinese & I18N
 *
 * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * See the file COPYING directory of this archive
 * Author: see CREDITS
 */

#include <stdlib.h>
#include <stdio.h>

typedef struct MemFile_handle
{
    void *pBuf;
    long nBeginPos, nLen;
    long nCurPos;
}
MemFile_T;

long openMemFile (FILE *fp, long nBegin, long nLen)
{
    MemFile_T *p;
    void *pBuf;

    if (fp == NULL)
       return 0;

    pBuf = (void*) malloc (nLen); 
    if (pBuf == NULL)
        return 0;

    fseek (fp, nBegin, SEEK_SET);
    nLen = fread (pBuf, 1, nLen, fp);

    p = (MemFile_T *) malloc (sizeof (MemFile_T)); 
    if (p == NULL)
    {
        free (pBuf);
        return 0;
    }
    p->nLen = nLen;
    p->nBeginPos = p->nCurPos = nBegin;
    p->pBuf = pBuf;
    return (long) p;
}

long closeMemFile (long handle)
{
    MemFile_T *p = (MemFile_T *) handle;
    free (p->pBuf);
    free (p);
    return 0;
}

int readMemFile (long handle, long nLen, void *buf)
{
    MemFile_T *p = (MemFile_T *) handle;
    char  *a = (char *) p->pBuf;
    void *p1 = (void *) &a[p->nCurPos - p->nBeginPos];
    memcpy (buf, p1, nLen);
    p->nCurPos += nLen;
    return nLen;
}

long lseekMemFile (long handle, long nNewBegin)
{
    MemFile_T *p = (MemFile_T *) handle;
    p->nCurPos = nNewBegin;
    return nNewBegin;
}

long ftellMemFile (long handle)
{
    MemFile_T *p = (MemFile_T *) handle;
    return p->nCurPos;
}