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
midibuf_message_length(unsigned char code)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
midibuf_is_empty(struct midi_buffer * this)36 static int midibuf_is_empty(struct midi_buffer *this)
37 {
38 return (this->pos_read == this->pos_write) && !this->full;
39 }
40
midibuf_is_full(struct midi_buffer * this)41 static int midibuf_is_full(struct midi_buffer *this)
42 {
43 return this->full;
44 }
45
line6_midibuf_reset(struct midi_buffer * this)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
line6_midibuf_init(struct midi_buffer * this,int size,int split)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
line6_midibuf_status(struct midi_buffer * this)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
line6_midibuf_bytes_free(struct midi_buffer * this)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
line6_midibuf_bytes_used(struct midi_buffer * this)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
line6_midibuf_write(struct midi_buffer * this,unsigned char * data,int length)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
line6_midibuf_read(struct midi_buffer * this,unsigned char * data,int length)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
line6_midibuf_ignore(struct midi_buffer * this,int length)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
line6_midibuf_skip_message(struct midi_buffer * this,unsigned short mask)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
line6_midibuf_destroy(struct midi_buffer * this)261 void line6_midibuf_destroy(struct midi_buffer *this)
262 {
263 kfree(this->buf);
264 this->buf = NULL;
265 }
266