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 int line6_midibuf_bytes_free(struct midi_buffer *this) 71 { 72 return 73 midibuf_is_full(this) ? 74 0 : 75 (this->pos_read - this->pos_write + this->size - 1) % this->size + 76 1; 77 } 78 79 int line6_midibuf_bytes_used(struct midi_buffer *this) 80 { 81 return 82 midibuf_is_empty(this) ? 83 0 : 84 (this->pos_write - this->pos_read + this->size - 1) % this->size + 85 1; 86 } 87 88 int line6_midibuf_write(struct midi_buffer *this, unsigned char *data, 89 int length) 90 { 91 int bytes_free; 92 int length1, length2; 93 int skip_active_sense = 0; 94 95 if (midibuf_is_full(this) || (length <= 0)) 96 return 0; 97 98 /* skip trailing active sense */ 99 if (data[length - 1] == 0xfe) { 100 --length; 101 skip_active_sense = 1; 102 } 103 104 bytes_free = line6_midibuf_bytes_free(this); 105 106 if (length > bytes_free) 107 length = bytes_free; 108 109 if (length > 0) { 110 length1 = this->size - this->pos_write; 111 112 if (length < length1) { 113 /* no buffer wraparound */ 114 memcpy(this->buf + this->pos_write, data, length); 115 this->pos_write += length; 116 } else { 117 /* buffer wraparound */ 118 length2 = length - length1; 119 memcpy(this->buf + this->pos_write, data, length1); 120 memcpy(this->buf, data + length1, length2); 121 this->pos_write = length2; 122 } 123 124 if (this->pos_write == this->pos_read) 125 this->full = 1; 126 } 127 128 return length + skip_active_sense; 129 } 130 131 int line6_midibuf_read(struct midi_buffer *this, unsigned char *data, 132 int length) 133 { 134 int bytes_used; 135 int length1, length2; 136 int command; 137 int midi_length; 138 int repeat = 0; 139 int i; 140 141 /* we need to be able to store at least a 3 byte MIDI message */ 142 if (length < 3) 143 return -EINVAL; 144 145 if (midibuf_is_empty(this)) 146 return 0; 147 148 bytes_used = line6_midibuf_bytes_used(this); 149 150 if (length > bytes_used) 151 length = bytes_used; 152 153 length1 = this->size - this->pos_read; 154 155 /* check MIDI command length */ 156 command = this->buf[this->pos_read]; 157 158 if (command & 0x80) { 159 midi_length = midibuf_message_length(command); 160 this->command_prev = command; 161 } else { 162 if (this->command_prev > 0) { 163 int midi_length_prev = 164 midibuf_message_length(this->command_prev); 165 166 if (midi_length_prev > 0) { 167 midi_length = midi_length_prev - 1; 168 repeat = 1; 169 } else 170 midi_length = -1; 171 } else 172 midi_length = -1; 173 } 174 175 if (midi_length < 0) { 176 /* search for end of message */ 177 if (length < length1) { 178 /* no buffer wraparound */ 179 for (i = 1; i < length; ++i) 180 if (this->buf[this->pos_read + i] & 0x80) 181 break; 182 183 midi_length = i; 184 } else { 185 /* buffer wraparound */ 186 length2 = length - length1; 187 188 for (i = 1; i < length1; ++i) 189 if (this->buf[this->pos_read + i] & 0x80) 190 break; 191 192 if (i < length1) 193 midi_length = i; 194 else { 195 for (i = 0; i < length2; ++i) 196 if (this->buf[i] & 0x80) 197 break; 198 199 midi_length = length1 + i; 200 } 201 } 202 203 if (midi_length == length) 204 midi_length = -1; /* end of message not found */ 205 } 206 207 if (midi_length < 0) { 208 if (!this->split) 209 return 0; /* command is not yet complete */ 210 } else { 211 if (length < midi_length) 212 return 0; /* command is not yet complete */ 213 214 length = midi_length; 215 } 216 217 if (length < length1) { 218 /* no buffer wraparound */ 219 memcpy(data + repeat, this->buf + this->pos_read, length); 220 this->pos_read += length; 221 } else { 222 /* buffer wraparound */ 223 length2 = length - length1; 224 memcpy(data + repeat, this->buf + this->pos_read, length1); 225 memcpy(data + repeat + length1, this->buf, length2); 226 this->pos_read = length2; 227 } 228 229 if (repeat) 230 data[0] = this->command_prev; 231 232 this->full = 0; 233 return length + repeat; 234 } 235 236 int line6_midibuf_ignore(struct midi_buffer *this, int length) 237 { 238 int bytes_used = line6_midibuf_bytes_used(this); 239 240 if (length > bytes_used) 241 length = bytes_used; 242 243 this->pos_read = (this->pos_read + length) % this->size; 244 this->full = 0; 245 return length; 246 } 247 248 void line6_midibuf_destroy(struct midi_buffer *this) 249 { 250 kfree(this->buf); 251 this->buf = NULL; 252 } 253