drivers/staging/line6/midibuf.c

   1 /*
   2  * Line6 Linux USB driver - 0.9.1beta
   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 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                 };
  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 }