206 lines
6.3 KiB
C
206 lines
6.3 KiB
C
/**
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* \addtogroup c64fs
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* @{
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*/
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/**
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* \file
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* "Raw" C64 file system access.
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* \author Adam Dunkels <adam@dunkels.com>
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*
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* This file provides functions that allow reading data from files
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* without updating the file descriptor pointer. The functions are not
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* automatically included in the core Contiki code and therefore
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* application programs that use tham must manually link with this
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* file.
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*
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*/
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/*
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* Copyright (c) 2003, Adam Dunkels.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following
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* disclaimer in the documentation and/or other materials provided
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* with the distribution.
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* 3. The name of the author may not be used to endorse or promote
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* products derived from this software without specific prior
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* written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
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* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
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* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* This file is part of the Contiki desktop environment
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*
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* $Id: c64-fs-raw.c,v 1.1 2007/05/23 23:11:28 oliverschmidt Exp $
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*
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*/
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#include "c64-fs-raw.h"
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#include <string.h>
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struct directory_entry {
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unsigned char type;
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unsigned char track, sect;
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unsigned char name[16];
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unsigned char reltrack, relsect, relreclen;
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unsigned char unused1, unused2, unused3, unused4;
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unsigned char tmptrack, tmpsect;
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unsigned char blockslo, blockshi;
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};
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extern unsigned char _c64_fs_dirbuf[256];
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extern unsigned char _c64_fs_dirbuftrack, _c64_fs_dirbufsect;
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extern unsigned char _c64_fs_filebuf[256];
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extern unsigned char _c64_fs_filebuftrack, _c64_fs_filebufsect;
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void _c64_fs_readdirbuf(unsigned char track, unsigned char sect);
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/*-----------------------------------------------------------------------------------*/
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/**
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* Read data from a file without updating the file descriptor pointer.
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*
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* This function reads data from an open file into a buffer than must
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* be allocated by the caller, but does not update the file
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* description pointer like the c64_fs_read() function does.
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*
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* \param f A pointer to a file descriptor structure that must have
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* been opened with c64_fs_open().
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*
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* \param buf A pointer to the buffer in which the data should be placed.
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*
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* \param len The maxiumum amount of bytes to read.
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*
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* \return The number of bytes that actually was read, or 0 if an end
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* of file was encountered.
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*
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*/
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/*-----------------------------------------------------------------------------------*/
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int __fastcall__
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c64_fs_read_raw(register struct c64_fs_file *f, char *buf, int len)
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{
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int i;
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unsigned char fptr, ftrack, fsect;
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/* Check if current block is already in buffer, and if not read it
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from disk. */
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if(_c64_fs_filebuftrack != f->track ||
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_c64_fs_filebufsect != f->sect) {
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_c64_fs_filebuftrack = f->track;
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_c64_fs_filebufsect = f->sect;
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c64_dio_read_block(_c64_fs_filebuftrack,
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_c64_fs_filebufsect, _c64_fs_filebuf);
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}
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if(_c64_fs_filebuf[0] == 0 &&
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f->ptr == _c64_fs_filebuf[1]) {
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return 0; /* EOF */
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}
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fptr = f->ptr;
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ftrack = f->track;
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fsect = f->sect;
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for(i = 0; i < len; ++i) {
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*buf = _c64_fs_filebuf[fptr];
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++fptr;
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if(_c64_fs_filebuf[0] == 0) {
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if(fptr == _c64_fs_filebuf[1]) {
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/* End of file reached, we return the amount of bytes read so
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far. */
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return i + 1;
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}
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} else if(fptr == 0) {
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/* Read new block into buffer and set buffer state
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accordingly. */
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_c64_fs_filebuftrack = ftrack = _c64_fs_filebuf[0];
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_c64_fs_filebufsect = fsect = _c64_fs_filebuf[1];
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fptr = 2;
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c64_dio_read_block(_c64_fs_filebuftrack,
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_c64_fs_filebufsect, _c64_fs_filebuf);
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}
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++buf;
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}
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return i;
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}
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/*-----------------------------------------------------------------------------------*/
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/**
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* Move the file descriptior pointer forward in the file.
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*
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*
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* \param f A pointer to a file descriptor structure that must have
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* been opened with c64_fs_open().
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*
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* \param len The number of bytes the pointer should be moved forward.
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*
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* \return The number of bytes that the pointer actually was moved, or
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* 0 if an end of file was encountered.
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*/
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/*-----------------------------------------------------------------------------------*/
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int
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c64_fs_read_next(register struct c64_fs_file *f, int len)
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{
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int i;
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/* Check if current block is already in buffer, and if not read it
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from disk. */
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if(_c64_fs_filebuftrack != f->track ||
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_c64_fs_filebufsect != f->sect) {
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_c64_fs_filebuftrack = f->track;
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_c64_fs_filebufsect = f->sect;
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c64_dio_read_block(_c64_fs_filebuftrack,
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_c64_fs_filebufsect, _c64_fs_filebuf);
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}
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if(_c64_fs_filebuf[0] == 0 &&
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f->ptr == _c64_fs_filebuf[1]) {
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return 0; /* EOF */
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}
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for(i = 0; i < len; ++i) {
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++f->ptr;
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if(_c64_fs_filebuf[0] == 0) {
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if(f->ptr == _c64_fs_filebuf[1]) {
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/* End of file reached, we return the amount of bytes read so
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far. */
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return i + 1;
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}
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} else if(f->ptr == 0) {
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/* Read new block into buffer and set buffer state
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accordingly. */
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_c64_fs_filebuftrack = f->track = _c64_fs_filebuf[0];
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_c64_fs_filebufsect = f->sect = _c64_fs_filebuf[1];
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f->ptr = 2;
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c64_dio_read_block(_c64_fs_filebuftrack,
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_c64_fs_filebufsect, _c64_fs_filebuf);
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}
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}
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return i;
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}
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/*-----------------------------------------------------------------------------------*/
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/** @} */
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