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         if (code < 0x80)
  19                 return -1;
  20         else if (code < 0xf0) {
  21                 static const int length[] = { 3, 3, 3, 3, 2, 2, 3 };
  22                 return length[(code >> 4) - 8];
  23         } else {
  24                 /*
  25                    Note that according to the MIDI specification 0xf2 is
  26                    the "Song Position Pointer", but this is used by Line6
  27                    to send sysex messages to the host.
  28                  */
  29                 static const int length[] = { -1, 2, -1, 2, -1, -1, 1, 1, 1, 1,
  30                         1, 1, 1, -1, 1, 1
  31                 };
  32                 return length[code & 0x0f];
  33         }
  34 }
  35
  36 static int midibuf_is_empty(struct MidiBuffer *this)
  37 {
  38         return (this->pos_read == this->pos_write) && !this->full;
  39 }
  40
  41 static int midibuf_is_full(struct MidiBuffer *this)
  42 {
  43         return this->full;
  44 }
  45
  46 void line6_midibuf_reset(struct MidiBuffer *this)
  47 {
  48         this->pos_read = this->pos_write = this->full = 0;
  49         this->command_prev = -1;
  50 }
  51
  52 int line6_midibuf_init(struct MidiBuffer *this, int size, int split)
  53 {
  54         this->buf = kmalloc(size, GFP_KERNEL);
  55
  56         if (this->buf == NULL)
  57                 return -ENOMEM;
  58
  59         this->size = size;
  60         this->split = split;
  61         line6_midibuf_reset(this);
  62         return 0;
  63 }
  64
  65 void line6_midibuf_status(struct MidiBuffer *this)
  66 {
  67         pr_debug("midibuf size=%d split=%d pos_read=%d pos_write=%d "
  68                "full=%d command_prev=%02x\n", this->size, this->split,
  69                this->pos_read, this->pos_write, this->full, this->command_prev);
  70 }
  71
  72 int line6_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 +
  78             1;
  79 }
  80
  81 int line6_midibuf_bytes_used(struct MidiBuffer *this)
  82 {
  83         return
  84             midibuf_is_empty(this) ?
  85             0 :
  86             (this->pos_write - this->pos_read + this->size - 1) % this->size +
  87             1;
  88 }
  89
  90 int line6_midibuf_write(struct MidiBuffer *this, unsigned char *data,
  91                         int length)
  92 {
  93         int bytes_free;
  94         int length1, length2;
  95         int skip_active_sense = 0;
  96
  97         if (midibuf_is_full(this) || (length <= 0))
  98                 return 0;
  99
 100         /* skip trailing active sense */
 101         if (data[length - 1] == 0xfe) {
 102                 --length;
 103                 skip_active_sense = 1;
 104         }
 105
 106         bytes_free = line6_midibuf_bytes_free(this);
 107
 108         if (length > bytes_free)
 109                 length = bytes_free;
 110
 111         if (length > 0) {
 112                 length1 = this->size - this->pos_write;
 113
 114                 if (length < length1) {
 115                         /* no buffer wraparound */
 116                         memcpy(this->buf + this->pos_write, data, length);
 117                         this->pos_write += length;
 118                 } else {
 119                         /* buffer wraparound */
 120                         length2 = length - length1;
 121                         memcpy(this->buf + this->pos_write, data, length1);
 122                         memcpy(this->buf, data + length1, length2);
 123                         this->pos_write = length2;
 124                 }
 125
 126                 if (this->pos_write == this->pos_read)
 127                         this->full = 1;
 128         }
 129
 130         return length + skip_active_sense;
 131 }
 132
 133 int line6_midibuf_read(struct MidiBuffer *this, unsigned char *data, int length)
 134 {
 135         int bytes_used;
 136         int length1, length2;
 137         int command;
 138         int midi_length;
 139         int repeat = 0;
 140         int i;
 141
 142         /* we need to be able to store at least a 3 byte MIDI message */
 143         if (length < 3)
 144                 return -EINVAL;
 145
 146         if (midibuf_is_empty(this))
 147                 return 0;
 148
 149         bytes_used = line6_midibuf_bytes_used(this);
 150
 151         if (length > bytes_used)
 152                 length = bytes_used;
 153
 154         length1 = this->size - this->pos_read;
 155
 156         /* check MIDI command length */
 157         command = this->buf[this->pos_read];
 158
 159         if (command & 0x80) {
 160                 midi_length = midibuf_message_length(command);
 161                 this->command_prev = command;
 162         } else {
 163                 if (this->command_prev > 0) {
 164                         int midi_length_prev =
 165                             midibuf_message_length(this->command_prev);
 166
 167                         if (midi_length_prev > 0) {
 168                                 midi_length = midi_length_prev - 1;
 169                                 repeat = 1;
 170                         } else
 171                                 midi_length = -1;
 172                 } else
 173                         midi_length = -1;
 174         }
 175
 176         if (midi_length < 0) {
 177                 /* search for end of message */
 178                 if (length < length1) {
 179                         /* no buffer wraparound */
 180                         for (i = 1; i < length; ++i)
 181                                 if (this->buf[this->pos_read + i] & 0x80)
 182                                         break;
 183
 184                         midi_length = i;
 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         } else {
 212                 if (length < midi_length)
 213                         return 0;       /* command is not yet complete */
 214
 215                 length = midi_length;
 216         }
 217
 218         if (length < length1) {
 219                 /* no buffer wraparound */
 220                 memcpy(data + repeat, this->buf + this->pos_read, length);
 221                 this->pos_read += length;
 222         } else {
 223                 /* buffer wraparound */
 224                 length2 = length - length1;
 225                 memcpy(data + repeat, this->buf + this->pos_read, length1);
 226                 memcpy(data + repeat + length1, this->buf, length2);
 227                 this->pos_read = length2;
 228         }
 229
 230         if (repeat)
 231                 data[0] = this->command_prev;
 232
 233         this->full = 0;
 234         return length + repeat;
 235 }
 236
 237 int line6_midibuf_ignore(struct MidiBuffer *this, int length)
 238 {
 239         int bytes_used = line6_midibuf_bytes_used(this);
 240
 241         if (length > bytes_used)
 242                 length = bytes_used;
 243
 244         this->pos_read = (this->pos_read + length) % this->size;
 245         this->full = 0;
 246         return length;
 247 }
 248
 249 int line6_midibuf_skip_message(struct MidiBuffer *this, unsigned short mask)
 250 {
 251         int cmd = this->command_prev;
 252
 253         if ((cmd >= 0x80) && (cmd < 0xf0))
 254                 if ((mask & (1 << (cmd & 0x0f))) == 0)
 255                         return 1;
 256
 257         return 0;
 258 }
 259
 260 void line6_midibuf_destroy(struct MidiBuffer *this)
 261 {
 262         kfree(this->buf);
 263         this->buf = NULL;
 264 }