1 /* 2 * Line 6 Linux USB driver 3 * 4 * Copyright (C) 2004-2010 Markus Grabner (grabner@icg.tugraz.at) 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License as 8 * published by the Free Software Foundation, version 2. 9 * 10 */ 11 12 #include <linux/slab.h> 13 14 #include "midibuf.h" 15 16 static int midibuf_message_length(unsigned char code) 17 { 18 int message_length; 19 20 if (code < 0x80) 21 message_length = -1; 22 else if (code < 0xf0) { 23 static const int length[] = { 3, 3, 3, 3, 2, 2, 3 }; 24 25 message_length = length[(code >> 4) - 8]; 26 } else { 27 /* 28 Note that according to the MIDI specification 0xf2 is 29 the "Song Position Pointer", but this is used by Line 6 30 to send sysex messages to the host. 31 */ 32 static const int length[] = { -1, 2, -1, 2, -1, -1, 1, 1, 1, 1, 33 1, 1, 1, -1, 1, 1 34 }; 35 message_length = length[code & 0x0f]; 36 } 37 38 return message_length; 39 } 40 41 static int midibuf_is_empty(struct midi_buffer *this) 42 { 43 return (this->pos_read == this->pos_write) && !this->full; 44 } 45 46 static int midibuf_is_full(struct midi_buffer *this) 47 { 48 return this->full; 49 } 50 51 void line6_midibuf_reset(struct midi_buffer *this) 52 { 53 this->pos_read = this->pos_write = this->full = 0; 54 this->command_prev = -1; 55 } 56 57 int line6_midibuf_init(struct midi_buffer *this, int size, int split) 58 { 59 this->buf = kmalloc(size, GFP_KERNEL); 60 61 if (this->buf == NULL) 62 return -ENOMEM; 63 64 this->size = size; 65 this->split = split; 66 line6_midibuf_reset(this); 67 return 0; 68 } 69 70 void line6_midibuf_status(struct midi_buffer *this) 71 { 72 pr_debug("midibuf size=%d split=%d pos_read=%d pos_write=%d full=%d command_prev=%02x\n", 73 this->size, this->split, this->pos_read, this->pos_write, 74 this->full, this->command_prev); 75 } 76 77 int line6_midibuf_bytes_free(struct midi_buffer *this) 78 { 79 return 80 midibuf_is_full(this) ? 81 0 : 82 (this->pos_read - this->pos_write + this->size - 1) % this->size + 83 1; 84 } 85 86 int line6_midibuf_bytes_used(struct midi_buffer *this) 87 { 88 return 89 midibuf_is_empty(this) ? 90 0 : 91 (this->pos_write - this->pos_read + this->size - 1) % this->size + 92 1; 93 } 94 95 int line6_midibuf_write(struct midi_buffer *this, unsigned char *data, 96 int length) 97 { 98 int bytes_free; 99 int length1, length2; 100 int skip_active_sense = 0; 101 102 if (midibuf_is_full(this) || (length <= 0)) 103 return 0; 104 105 /* skip trailing active sense */ 106 if (data[length - 1] == 0xfe) { 107 --length; 108 skip_active_sense = 1; 109 } 110 111 bytes_free = line6_midibuf_bytes_free(this); 112 113 if (length > bytes_free) 114 length = bytes_free; 115 116 if (length > 0) { 117 length1 = this->size - this->pos_write; 118 119 if (length < length1) { 120 /* no buffer wraparound */ 121 memcpy(this->buf + this->pos_write, data, length); 122 this->pos_write += length; 123 } else { 124 /* buffer wraparound */ 125 length2 = length - length1; 126 memcpy(this->buf + this->pos_write, data, length1); 127 memcpy(this->buf, data + length1, length2); 128 this->pos_write = length2; 129 } 130 131 if (this->pos_write == this->pos_read) 132 this->full = 1; 133 } 134 135 return length + skip_active_sense; 136 } 137 138 int line6_midibuf_read(struct midi_buffer *this, unsigned char *data, 139 int length) 140 { 141 int bytes_used; 142 int length1, length2; 143 int command; 144 int midi_length; 145 int repeat = 0; 146 int i; 147 148 /* we need to be able to store at least a 3 byte MIDI message */ 149 if (length < 3) 150 return -EINVAL; 151 152 if (midibuf_is_empty(this)) 153 return 0; 154 155 bytes_used = line6_midibuf_bytes_used(this); 156 157 if (length > bytes_used) 158 length = bytes_used; 159 160 length1 = this->size - this->pos_read; 161 162 /* check MIDI command length */ 163 command = this->buf[this->pos_read]; 164 165 if (command & 0x80) { 166 midi_length = midibuf_message_length(command); 167 this->command_prev = command; 168 } else { 169 if (this->command_prev > 0) { 170 int midi_length_prev = 171 midibuf_message_length(this->command_prev); 172 173 if (midi_length_prev > 0) { 174 midi_length = midi_length_prev - 1; 175 repeat = 1; 176 } else 177 midi_length = -1; 178 } else 179 midi_length = -1; 180 } 181 182 if (midi_length < 0) { 183 /* search for end of message */ 184 if (length < length1) { 185 /* no buffer wraparound */ 186 for (i = 1; i < length; ++i) 187 if (this->buf[this->pos_read + i] & 0x80) 188 break; 189 190 midi_length = i; 191 } else { 192 /* buffer wraparound */ 193 length2 = length - length1; 194 195 for (i = 1; i < length1; ++i) 196 if (this->buf[this->pos_read + i] & 0x80) 197 break; 198 199 if (i < length1) 200 midi_length = i; 201 else { 202 for (i = 0; i < length2; ++i) 203 if (this->buf[i] & 0x80) 204 break; 205 206 midi_length = length1 + i; 207 } 208 } 209 210 if (midi_length == length) 211 midi_length = -1; /* end of message not found */ 212 } 213 214 if (midi_length < 0) { 215 if (!this->split) 216 return 0; /* command is not yet complete */ 217 } else { 218 if (length < midi_length) 219 return 0; /* command is not yet complete */ 220 221 length = midi_length; 222 } 223 224 if (length < length1) { 225 /* no buffer wraparound */ 226 memcpy(data + repeat, this->buf + this->pos_read, length); 227 this->pos_read += length; 228 } else { 229 /* buffer wraparound */ 230 length2 = length - length1; 231 memcpy(data + repeat, this->buf + this->pos_read, length1); 232 memcpy(data + repeat + length1, this->buf, length2); 233 this->pos_read = length2; 234 } 235 236 if (repeat) 237 data[0] = this->command_prev; 238 239 this->full = 0; 240 return length + repeat; 241 } 242 243 int line6_midibuf_ignore(struct midi_buffer *this, int length) 244 { 245 int bytes_used = line6_midibuf_bytes_used(this); 246 247 if (length > bytes_used) 248 length = bytes_used; 249 250 this->pos_read = (this->pos_read + length) % this->size; 251 this->full = 0; 252 return length; 253 } 254 255 int line6_midibuf_skip_message(struct midi_buffer *this, unsigned short mask) 256 { 257 int cmd = this->command_prev; 258 259 if ((cmd >= 0x80) && (cmd < 0xf0)) 260 if ((mask & (1 << (cmd & 0x0f))) == 0) 261 return 1; 262 263 return 0; 264 } 265 266 void line6_midibuf_destroy(struct midi_buffer *this) 267 { 268 kfree(this->buf); 269 this->buf = NULL; 270 } 271