kthacker | 6de6775 | 2006-04-17 15:02:26 +0000 | [diff] [blame^] | 1 | /** |
| 2 | * \addtogroup c64fs |
| 3 | * @{ |
| 4 | */ |
| 5 | |
| 6 | /** |
| 7 | * \file |
| 8 | * "Raw" C64 file system access. |
| 9 | * \author Adam Dunkels <adam@dunkels.com> |
| 10 | * |
| 11 | * This file provides functions that allow reading data from files |
| 12 | * without updating the file descriptor pointer. The functions are not |
| 13 | * automatically included in the core Contiki code and therefore |
| 14 | * application programs that use tham must manually link with this |
| 15 | * file. |
| 16 | * |
| 17 | */ |
| 18 | |
| 19 | |
| 20 | /* |
| 21 | * Copyright (c) 2003, Adam Dunkels. |
| 22 | * All rights reserved. |
| 23 | * |
| 24 | * Redistribution and use in source and binary forms, with or without |
| 25 | * modification, are permitted provided that the following conditions |
| 26 | * are met: |
| 27 | * 1. Redistributions of source code must retain the above copyright |
| 28 | * notice, this list of conditions and the following disclaimer. |
| 29 | * 2. Redistributions in binary form must reproduce the above |
| 30 | * copyright notice, this list of conditions and the following |
| 31 | * disclaimer in the documentation and/or other materials provided |
| 32 | * with the distribution. |
| 33 | * 3. The name of the author may not be used to endorse or promote |
| 34 | * products derived from this software without specific prior |
| 35 | * written permission. |
| 36 | * |
| 37 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS |
| 38 | * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED |
| 39 | * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 40 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY |
| 41 | * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 42 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE |
| 43 | * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| 44 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
| 45 | * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
| 46 | * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
| 47 | * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 48 | * |
| 49 | * This file is part of the Contiki desktop environment |
| 50 | * |
| 51 | * $Id: c64-fs-raw.c,v 1.1 2006/04/17 15:02:37 kthacker Exp $ |
| 52 | * |
| 53 | */ |
| 54 | |
| 55 | #include "c64-fs-raw.h" |
| 56 | |
| 57 | #include <string.h> |
| 58 | |
| 59 | struct directory_entry { |
| 60 | unsigned char type; |
| 61 | unsigned char track, sect; |
| 62 | unsigned char name[16]; |
| 63 | unsigned char reltrack, relsect, relreclen; |
| 64 | unsigned char unused1, unused2, unused3, unused4; |
| 65 | unsigned char tmptrack, tmpsect; |
| 66 | unsigned char blockslo, blockshi; |
| 67 | }; |
| 68 | |
| 69 | |
| 70 | extern unsigned char _c64_fs_dirbuf[256]; |
| 71 | extern unsigned char _c64_fs_dirbuftrack, _c64_fs_dirbufsect; |
| 72 | |
| 73 | extern unsigned char _c64_fs_filebuf[256]; |
| 74 | extern unsigned char _c64_fs_filebuftrack, _c64_fs_filebufsect; |
| 75 | |
| 76 | void _c64_fs_readdirbuf(unsigned char track, unsigned char sect); |
| 77 | |
| 78 | |
| 79 | /*-----------------------------------------------------------------------------------*/ |
| 80 | /** |
| 81 | * Read data from a file without updating the file descriptor pointer. |
| 82 | * |
| 83 | * This function reads data from an open file into a buffer than must |
| 84 | * be allocated by the caller, but does not update the file |
| 85 | * description pointer like the c64_fs_read() function does. |
| 86 | * |
| 87 | * \param f A pointer to a file descriptor structure that must have |
| 88 | * been opened with c64_fs_open(). |
| 89 | * |
| 90 | * \param buf A pointer to the buffer in which the data should be placed. |
| 91 | * |
| 92 | * \param len The maxiumum amount of bytes to read. |
| 93 | * |
| 94 | * \return The number of bytes that actually was read, or 0 if an end |
| 95 | * of file was encountered. |
| 96 | * |
| 97 | */ |
| 98 | /*-----------------------------------------------------------------------------------*/ |
| 99 | int __fastcall__ |
| 100 | c64_fs_read_raw(register struct c64_fs_file *f, char *buf, int len) |
| 101 | { |
| 102 | int i; |
| 103 | unsigned char fptr, ftrack, fsect; |
| 104 | |
| 105 | /* Check if current block is already in buffer, and if not read it |
| 106 | from disk. */ |
| 107 | if(_c64_fs_filebuftrack != f->track || |
| 108 | _c64_fs_filebufsect != f->sect) { |
| 109 | _c64_fs_filebuftrack = f->track; |
| 110 | _c64_fs_filebufsect = f->sect; |
| 111 | c64_dio_read_block(_c64_fs_filebuftrack, |
| 112 | _c64_fs_filebufsect, _c64_fs_filebuf); |
| 113 | } |
| 114 | |
| 115 | if(_c64_fs_filebuf[0] == 0 && |
| 116 | f->ptr == _c64_fs_filebuf[1]) { |
| 117 | return 0; /* EOF */ |
| 118 | } |
| 119 | |
| 120 | fptr = f->ptr; |
| 121 | ftrack = f->track; |
| 122 | fsect = f->sect; |
| 123 | |
| 124 | for(i = 0; i < len; ++i) { |
| 125 | *buf = _c64_fs_filebuf[fptr]; |
| 126 | |
| 127 | ++fptr; |
| 128 | if(_c64_fs_filebuf[0] == 0) { |
| 129 | if(fptr == _c64_fs_filebuf[1]) { |
| 130 | /* End of file reached, we return the amount of bytes read so |
| 131 | far. */ |
| 132 | return i + 1; |
| 133 | } |
| 134 | } else if(fptr == 0) { |
| 135 | |
| 136 | /* Read new block into buffer and set buffer state |
| 137 | accordingly. */ |
| 138 | _c64_fs_filebuftrack = ftrack = _c64_fs_filebuf[0]; |
| 139 | _c64_fs_filebufsect = fsect = _c64_fs_filebuf[1]; |
| 140 | fptr = 2; |
| 141 | c64_dio_read_block(_c64_fs_filebuftrack, |
| 142 | _c64_fs_filebufsect, _c64_fs_filebuf); |
| 143 | } |
| 144 | |
| 145 | ++buf; |
| 146 | } |
| 147 | return i; |
| 148 | } |
| 149 | /*-----------------------------------------------------------------------------------*/ |
| 150 | /** |
| 151 | * Move the file descriptior pointer forward in the file. |
| 152 | * |
| 153 | * |
| 154 | * \param f A pointer to a file descriptor structure that must have |
| 155 | * been opened with c64_fs_open(). |
| 156 | * |
| 157 | * \param len The number of bytes the pointer should be moved forward. |
| 158 | * |
| 159 | * \return The number of bytes that the pointer actually was moved, or |
| 160 | * 0 if an end of file was encountered. |
| 161 | */ |
| 162 | /*-----------------------------------------------------------------------------------*/ |
| 163 | int |
| 164 | c64_fs_read_next(register struct c64_fs_file *f, int len) |
| 165 | { |
| 166 | int i; |
| 167 | |
| 168 | /* Check if current block is already in buffer, and if not read it |
| 169 | from disk. */ |
| 170 | if(_c64_fs_filebuftrack != f->track || |
| 171 | _c64_fs_filebufsect != f->sect) { |
| 172 | _c64_fs_filebuftrack = f->track; |
| 173 | _c64_fs_filebufsect = f->sect; |
| 174 | c64_dio_read_block(_c64_fs_filebuftrack, |
| 175 | _c64_fs_filebufsect, _c64_fs_filebuf); |
| 176 | } |
| 177 | |
| 178 | if(_c64_fs_filebuf[0] == 0 && |
| 179 | f->ptr == _c64_fs_filebuf[1]) { |
| 180 | return 0; /* EOF */ |
| 181 | } |
| 182 | |
| 183 | for(i = 0; i < len; ++i) { |
| 184 | |
| 185 | ++f->ptr; |
| 186 | if(_c64_fs_filebuf[0] == 0) { |
| 187 | if(f->ptr == _c64_fs_filebuf[1]) { |
| 188 | /* End of file reached, we return the amount of bytes read so |
| 189 | far. */ |
| 190 | return i + 1; |
| 191 | } |
| 192 | } else if(f->ptr == 0) { |
| 193 | /* Read new block into buffer and set buffer state |
| 194 | accordingly. */ |
| 195 | _c64_fs_filebuftrack = f->track = _c64_fs_filebuf[0]; |
| 196 | _c64_fs_filebufsect = f->sect = _c64_fs_filebuf[1]; |
| 197 | f->ptr = 2; |
| 198 | c64_dio_read_block(_c64_fs_filebuftrack, |
| 199 | _c64_fs_filebufsect, _c64_fs_filebuf); |
| 200 | } |
| 201 | } |
| 202 | return i; |
| 203 | } |
| 204 | /*-----------------------------------------------------------------------------------*/ |
| 205 | /** @} */ |