1/* 2 * Line6 Linux USB driver - 0.8.0 3 * 4 * Copyright (C) 2004-2009 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 "config.h" 13 14#include <linux/slab.h> 15 16#include "midibuf.h" 17 18 19static int midibuf_message_length(unsigned char code) 20{ 21 if (code < 0x80) 22 return -1; 23 else if (code < 0xf0) { 24 static const int length[] = { 3, 3, 3, 3, 2, 2, 3 }; 25 return 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 Line6 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 return length[code & 0x0f]; 35 } 36} 37 38void midibuf_reset(struct MidiBuffer *this) 39{ 40 this->pos_read = this->pos_write = this->full = 0; 41 this->command_prev = -1; 42} 43 44int midibuf_init(struct MidiBuffer *this, int size, int split) 45{ 46 this->buf = kmalloc(size, GFP_KERNEL); 47 48 if (this->buf == NULL) 49 return -ENOMEM; 50 51 this->size = size; 52 this->split = split; 53 midibuf_reset(this); 54 return 0; 55} 56 57void midibuf_status(struct MidiBuffer *this) 58{ 59 printk(KERN_DEBUG "midibuf size=%d split=%d pos_read=%d pos_write=%d " 60 "full=%d command_prev=%02x\n", this->size, this->split, 61 this->pos_read, this->pos_write, this->full, this->command_prev); 62} 63 64static int midibuf_is_empty(struct MidiBuffer *this) 65{ 66 return (this->pos_read == this->pos_write) && !this->full; 67} 68 69static int midibuf_is_full(struct MidiBuffer *this) 70{ 71 return this->full; 72} 73 74int midibuf_bytes_free(struct MidiBuffer *this) 75{ 76 return 77 midibuf_is_full(this) ? 78 0 : 79 (this->pos_read - this->pos_write + this->size - 1) % this->size + 1; 80} 81 82int midibuf_bytes_used(struct MidiBuffer *this) 83{ 84 return 85 midibuf_is_empty(this) ? 86 0 : 87 (this->pos_write - this->pos_read + this->size - 1) % this->size + 1; 88} 89 90int midibuf_write(struct MidiBuffer *this, unsigned char *data, int length) 91{ 92 int bytes_free; 93 int length1, length2; 94 int skip_active_sense = 0; 95 96 if (midibuf_is_full(this) || (length <= 0)) 97 return 0; 98 99 /* skip trailing active sense */ 100 if (data[length - 1] == 0xfe) { 101 --length; 102 skip_active_sense = 1; 103 } 104 105 bytes_free = midibuf_bytes_free(this); 106 107 if (length > bytes_free) 108 length = bytes_free; 109 110 if (length > 0) { 111 length1 = this->size - this->pos_write; 112 113 if (length < length1) { 114 /* no buffer wraparound */ 115 memcpy(this->buf + this->pos_write, data, length); 116 this->pos_write += length; 117 } else { 118 /* buffer wraparound */ 119 length2 = length - length1; 120 memcpy(this->buf + this->pos_write, data, length1); 121 memcpy(this->buf, data + length1, length2); 122 this->pos_write = length2; 123 } 124 125 if (this->pos_write == this->pos_read) 126 this->full = 1; 127 } 128 129 return length + skip_active_sense; 130} 131 132int midibuf_read(struct MidiBuffer *this, unsigned char *data, 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 = 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 = midibuf_message_length(this->command_prev); 164 165 if (midi_length_prev > 0) { 166 midi_length = midi_length_prev - 1; 167 repeat = 1; 168 } else 169 midi_length = -1; 170 } else 171 midi_length = -1; 172 } 173 174 if (midi_length < 0) { 175 /* search for end of message */ 176 if (length < length1) { 177 /* no buffer wraparound */ 178 for (i = 1; i < length; ++i) 179 if (this->buf[this->pos_read + i] & 0x80) 180 break; 181 182 midi_length = i; 183 } else { 184 /* buffer wraparound */ 185 length2 = length - length1; 186 187 for (i = 1; i < length1; ++i) 188 if (this->buf[this->pos_read + i] & 0x80) 189 break; 190 191 if (i < length1) 192 midi_length = i; 193 else { 194 for (i = 0; i < length2; ++i) 195 if (this->buf[i] & 0x80) 196 break; 197 198 midi_length = length1 + i; 199 } 200 } 201 202 if (midi_length == length) 203 midi_length = -1; /* end of message not found */ 204 } 205 206 if (midi_length < 0) { 207 if (!this->split) 208 return 0; /* command is not yet complete */ 209 } else { 210 if (length < midi_length) 211 return 0; /* command is not yet complete */ 212 213 length = midi_length; 214 } 215 216 if (length < length1) { 217 /* no buffer wraparound */ 218 memcpy(data + repeat, this->buf + this->pos_read, length); 219 this->pos_read += length; 220 } else { 221 /* buffer wraparound */ 222 length2 = length - length1; 223 memcpy(data + repeat, this->buf + this->pos_read, length1); 224 memcpy(data + repeat + length1, this->buf, length2); 225 this->pos_read = length2; 226 } 227 228 if (repeat) 229 data[0] = this->command_prev; 230 231 this->full = 0; 232 return length + repeat; 233} 234 235int midibuf_ignore(struct MidiBuffer *this, int length) 236{ 237 int bytes_used = midibuf_bytes_used(this); 238 239 if (length > bytes_used) 240 length = bytes_used; 241 242 this->pos_read = (this->pos_read + length) % this->size; 243 this->full = 0; 244 return length; 245} 246 247int midibuf_skip_message(struct MidiBuffer *this, unsigned short mask) 248{ 249 int cmd = this->command_prev; 250 251 if ((cmd >= 0x80) && (cmd < 0xf0)) 252 if ((mask & (1 << (cmd & 0x0f))) == 0) 253 return 1; 254 255 return 0; 256} 257 258void midibuf_destroy(struct MidiBuffer *this) 259{ 260 kfree(this->buf); 261 this->buf = NULL; 262} 263