drivers/staging/line6/midibuf.c

   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
  19 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         }
  27         else {
  28                 /*
  29                         Note that according to the MIDI specification 0xf2 is the "Song Position
  30                         Pointer", but this is used by Line6 to send sysex messages to the host.
  31                 */
  32                 static const int length[] = { -1, 2, -1, 2, -1, -1, 1, 1, 1, 1, 1, 1, 1, -1, 1, 1 };
  33                 return length[code & 0x0f];
  34         }
  35 }
  36
  37 void midibuf_reset(struct MidiBuffer *this)
  38 {
  39         this->pos_read = this->pos_write = this->full = 0;
  40         this->command_prev = -1;
  41 }
  42
  43 int midibuf_init(struct MidiBuffer *this, int size, int split)
  44 {
  45         this->buf = (unsigned char *)kmalloc(size, GFP_KERNEL);
  46
  47         if(this->buf == 0)
  48                 return -ENOMEM;
  49
  50         this->size = size;
  51         this->split = split;
  52         midibuf_reset(this);
  53         return 0;
  54 }
  55
  56 void midibuf_status(struct MidiBuffer *this)
  57 {
  58         printk("midibuf size=%d split=%d pos_read=%d pos_write=%d full=%d command_prev=%02x\n",
  59                                  this->size, this->split, this->pos_read, this->pos_write, this->full, this->command_prev);
  60 }
  61
  62 int midibuf_is_empty(struct MidiBuffer *this)
  63 {
  64         return (this->pos_read == this->pos_write) && !this->full;
  65 }
  66
  67 int midibuf_is_full(struct MidiBuffer *this)
  68 {
  69         return this->full;
  70 }
  71
  72 int midibuf_bytes_free(struct MidiBuffer *this)
  73 {
  74         return
  75                 midibuf_is_full(this) ?
  76                 0 :
  77                 (this->pos_read - this->pos_write + this->size - 1) % this->size + 1;
  78 }
  79
  80 int midibuf_bytes_used(struct MidiBuffer *this)
  81 {
  82         return
  83                 midibuf_is_empty(this) ?
  84                 0 :
  85                 (this->pos_write - this->pos_read + this->size - 1) % this->size + 1;
  86 }
  87
  88 int midibuf_write(struct MidiBuffer *this, unsigned char *data, int length)
  89 {
  90         int bytes_free;
  91         int length1, length2;
  92         int skip_active_sense = 0;
  93
  94         if(midibuf_is_full(this) || (length <= 0))
  95                 return 0;
  96
  97         /* skip trailing active sense */
  98         if(data[length - 1] == 0xfe) {
  99                 --length;
 100                 skip_active_sense = 1;
 101         }
 102
 103         bytes_free = midibuf_bytes_free(this);
 104
 105         if(length > bytes_free)
 106                 length = bytes_free;
 107
 108         if(length > 0) {
 109                 length1 = this->size - this->pos_write;
 110
 111                 if(length < length1) {
 112                         /* no buffer wraparound */
 113                         memcpy(this->buf + this->pos_write, data, length);
 114                         this->pos_write += length;
 115                 }
 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 midibuf_read(struct MidiBuffer *this, unsigned char *data, int length)
 132 {
 133         int bytes_used;
 134         int length1, length2;
 135         int command;
 136         int midi_length;
 137         int repeat = 0;
 138         int i;
 139
 140         if(length < 3)
 141                 return -EINVAL;  /* we need to be able to store at least a 3 byte MIDI message */
 142
 143         if(midibuf_is_empty(this))
 144                 return 0;
 145
 146         bytes_used = midibuf_bytes_used(this);
 147
 148         if(length > bytes_used)
 149                 length = bytes_used;
 150
 151         length1 = this->size - this->pos_read;
 152
 153         /* check MIDI command length */
 154         command = this->buf[this->pos_read];
 155
 156         if(command & 0x80) {
 157                 midi_length = midibuf_message_length(command);
 158                 this->command_prev = command;
 159         }
 160         else {
 161                 if(this->command_prev > 0) {
 162                         int midi_length_prev = midibuf_message_length(this->command_prev);
 163
 164                         if(midi_length_prev > 0) {
 165                                 midi_length = midi_length_prev - 1;
 166                                 repeat = 1;
 167                         }
 168                         else
 169                                 midi_length = -1;
 170                 }
 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                 }
 185                 else {
 186                         /* buffer wraparound */
 187                         length2 = length - length1;
 188
 189                         for(i = 1; i < length1; ++i)
 190                                 if(this->buf[this->pos_read + i] & 0x80)
 191                                         break;
 192
 193                         if(i < length1)
 194                                 midi_length = i;
 195                         else {
 196                                 for(i = 0; i < length2; ++i)
 197                                         if(this->buf[i] & 0x80)
 198                                                 break;
 199
 200                                 midi_length = length1 + i;
 201                         }
 202                 }
 203
 204                 if(midi_length == length)
 205                         midi_length = -1;  /* end of message not found */
 206         }
 207
 208         if(midi_length < 0) {
 209                 if(!this->split)
 210                         return 0;  /* command is not yet complete */
 211         }
 212         else {
 213                 if(length < midi_length)
 214                         return 0;  /* command is not yet complete */
 215
 216                 length = midi_length;
 217         }
 218
 219         if(length < length1) {
 220                 /* no buffer wraparound */
 221                 memcpy(data + repeat, this->buf + this->pos_read, length);
 222                 this->pos_read += length;
 223         }
 224         else {
 225                 /* buffer wraparound */
 226                 length2 = length - length1;
 227                 memcpy(data + repeat, this->buf + this->pos_read, length1);
 228                 memcpy(data + repeat + length1, this->buf, length2);
 229                 this->pos_read = length2;
 230         }
 231
 232         if(repeat)
 233                 data[0] = this->command_prev;
 234
 235         this->full = 0;
 236         return length + repeat;
 237 }
 238
 239 int midibuf_ignore(struct MidiBuffer *this, int length)
 240 {
 241         int bytes_used = midibuf_bytes_used(this);
 242
 243         if(length > bytes_used)
 244                 length = bytes_used;
 245
 246         this->pos_read = (this->pos_read + length) % this->size;
 247         this->full = 0;
 248         return length;
 249 }
 250
 251 int midibuf_skip_message(struct MidiBuffer *this, unsigned short mask)
 252 {
 253         int cmd = this->command_prev;
 254
 255         if((cmd >= 0x80) && (cmd < 0xf0))
 256                 if((mask & (1 << (cmd & 0x0f))) == 0)
 257                         return 1;
 258
 259         return 0;
 260 }
 261
 262 void midibuf_destroy(struct MidiBuffer *this)
 263 {
 264         if(this->buf != 0) {
 265                 kfree(this->buf);
 266                 this->buf = 0;
 267         }
 268 }