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 midi_buffer *this)
  37 {
  38         return (this->pos_read == this->pos_write) && !this->full;
  39 }
  40
  41 static int midibuf_is_full(struct midi_buffer *this)
  42 {
  43         return this->full;
  44 }
  45
  46 void line6_midibuf_reset(struct midi_buffer *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 midi_buffer *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 midi_buffer *this)
  66 {
  67         pr_debug("midibuf size=%d split=%d pos_read=%d pos_write=%d full=%d command_prev=%02x\n",
  68                  this->size, this->split, this->pos_read, this->pos_write,
  69                  this->full, this->command_prev);
  70 }
  71
  72 int line6_midibuf_bytes_free(struct midi_buffer *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 midi_buffer *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 midi_buffer *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 midi_buffer *this, unsigned char *data,
 134                        int length)
 135 {
 136         int bytes_used;
 137         int length1, length2;
 138         int command;
 139         int midi_length;
 140         int repeat = 0;
 141         int i;
 142
 143         /* we need to be able to store at least a 3 byte MIDI message */
 144         if (length < 3)
 145                 return -EINVAL;
 146
 147         if (midibuf_is_empty(this))
 148                 return 0;
 149
 150         bytes_used = line6_midibuf_bytes_used(this);
 151
 152         if (length > bytes_used)
 153                 length = bytes_used;
 154
 155         length1 = this->size - this->pos_read;
 156
 157         /* check MIDI command length */
 158         command = this->buf[this->pos_read];
 159
 160         if (command & 0x80) {
 161                 midi_length = midibuf_message_length(command);
 162                 this->command_prev = command;
 163         } else {
 164                 if (this->command_prev > 0) {
 165                         int midi_length_prev =
 166                             midibuf_message_length(this->command_prev);
 167
 168                         if (midi_length_prev > 0) {
 169                                 midi_length = midi_length_prev - 1;
 170                                 repeat = 1;
 171                         } else
 172                                 midi_length = -1;
 173                 } else
 174                         midi_length = -1;
 175         }
 176
 177         if (midi_length < 0) {
 178                 /* search for end of message */
 179                 if (length < length1) {
 180                         /* no buffer wraparound */
 181                         for (i = 1; i < length; ++i)
 182                                 if (this->buf[this->pos_read + i] & 0x80)
 183                                         break;
 184
 185                         midi_length = i;
 186                 } else {
 187                         /* buffer wraparound */
 188                         length2 = length - length1;
 189
 190                         for (i = 1; i < length1; ++i)
 191                                 if (this->buf[this->pos_read + i] & 0x80)
 192                                         break;
 193
 194                         if (i < length1)
 195                                 midi_length = i;
 196                         else {
 197                                 for (i = 0; i < length2; ++i)
 198                                         if (this->buf[i] & 0x80)
 199                                                 break;
 200
 201                                 midi_length = length1 + i;
 202                         }
 203                 }
 204
 205                 if (midi_length == length)
 206                         midi_length = -1;       /* end of message not found */
 207         }
 208
 209         if (midi_length < 0) {
 210                 if (!this->split)
 211                         return 0;       /* command is not yet complete */
 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         } else {
 224                 /* buffer wraparound */
 225                 length2 = length - length1;
 226                 memcpy(data + repeat, this->buf + this->pos_read, length1);
 227                 memcpy(data + repeat + length1, this->buf, length2);
 228                 this->pos_read = length2;
 229         }
 230
 231         if (repeat)
 232                 data[0] = this->command_prev;
 233
 234         this->full = 0;
 235         return length + repeat;
 236 }
 237
 238 int line6_midibuf_ignore(struct midi_buffer *this, int length)
 239 {
 240         int bytes_used = line6_midibuf_bytes_used(this);
 241
 242         if (length > bytes_used)
 243                 length = bytes_used;
 244
 245         this->pos_read = (this->pos_read + length) % this->size;
 246         this->full = 0;
 247         return length;
 248 }
 249
 250 int line6_midibuf_skip_message(struct midi_buffer *this, unsigned short mask)
 251 {
 252         int cmd = this->command_prev;
 253
 254         if ((cmd >= 0x80) && (cmd < 0xf0))
 255                 if ((mask & (1 << (cmd & 0x0f))) == 0)
 256                         return 1;
 257
 258         return 0;
 259 }
 260
 261 void line6_midibuf_destroy(struct midi_buffer *this)
 262 {
 263         kfree(this->buf);
 264         this->buf = NULL;
 265 }