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 static 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
  38 void midibuf_reset(struct MidiBuffer *this)
  39 {
  40         this->pos_read = this->pos_write = this->full = 0;
  41         this->command_prev = -1;
  42 }
  43
  44 int 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
  57 void 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
  64 static int midibuf_is_empty(struct MidiBuffer *this)
  65 {
  66         return (this->pos_read == this->pos_write) && !this->full;
  67 }
  68
  69 static int midibuf_is_full(struct MidiBuffer *this)
  70 {
  71         return this->full;
  72 }
  73
  74 int 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
  82 int 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
  90 int 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
 132 int 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
 235 int 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
 247 int 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
 258 void midibuf_destroy(struct MidiBuffer *this)
 259 {
 260         kfree(this->buf);
 261         this->buf = NULL;
 262 }