1 // SPDX-License-Identifier: GPL-2.0-only
3 * Line 6 Linux USB driver
5 * Copyright (C) 2004-2010 Markus Grabner (grabner@icg.tugraz.at)
8 #include <linux/slab.h>
13 static int midibuf_message_length(unsigned char code)
19 else if (code < 0xf0) {
20 static const int length[] = { 3, 3, 3, 3, 2, 2, 3 };
22 message_length = length[(code >> 4) - 8];
24 static const int length[] = { -1, 2, 2, 2, -1, -1, 1, 1, 1, -1,
27 message_length = length[code & 0x0f];
30 return message_length;
33 static int midibuf_is_empty(struct midi_buffer *this)
35 return (this->pos_read == this->pos_write) && !this->full;
38 static int midibuf_is_full(struct midi_buffer *this)
43 void line6_midibuf_reset(struct midi_buffer *this)
45 this->pos_read = this->pos_write = this->full = 0;
46 this->command_prev = -1;
49 int line6_midibuf_init(struct midi_buffer *this, int size, int split)
51 this->buf = kmalloc(size, GFP_KERNEL);
53 if (this->buf == NULL)
58 line6_midibuf_reset(this);
62 int line6_midibuf_bytes_free(struct midi_buffer *this)
65 midibuf_is_full(this) ?
67 (this->pos_read - this->pos_write + this->size - 1) % this->size +
71 int line6_midibuf_bytes_used(struct midi_buffer *this)
74 midibuf_is_empty(this) ?
76 (this->pos_write - this->pos_read + this->size - 1) % this->size +
80 int line6_midibuf_write(struct midi_buffer *this, unsigned char *data,
85 int skip_active_sense = 0;
87 if (midibuf_is_full(this) || (length <= 0))
90 /* skip trailing active sense */
91 if (data[length - 1] == 0xfe) {
93 skip_active_sense = 1;
96 bytes_free = line6_midibuf_bytes_free(this);
98 if (length > bytes_free)
102 length1 = this->size - this->pos_write;
104 if (length < length1) {
105 /* no buffer wraparound */
106 memcpy(this->buf + this->pos_write, data, length);
107 this->pos_write += length;
109 /* buffer wraparound */
110 length2 = length - length1;
111 memcpy(this->buf + this->pos_write, data, length1);
112 memcpy(this->buf, data + length1, length2);
113 this->pos_write = length2;
116 if (this->pos_write == this->pos_read)
120 return length + skip_active_sense;
123 int line6_midibuf_read(struct midi_buffer *this, unsigned char *data,
124 int length, int read_type)
127 int length1, length2;
133 /* we need to be able to store at least a 3 byte MIDI message */
137 if (midibuf_is_empty(this))
140 bytes_used = line6_midibuf_bytes_used(this);
142 if (length > bytes_used)
145 length1 = this->size - this->pos_read;
147 command = this->buf[this->pos_read];
149 PODxt always has status byte lower nibble set to 0010,
150 when it means to send 0000, so we correct if here so
151 that control/program changes come on channel 1 and
152 sysex message status byte is correct
154 if (read_type == LINE6_MIDIBUF_READ_RX) {
155 if (command == 0xb2 || command == 0xc2 || command == 0xf2) {
156 unsigned char fixed = command & 0xf0;
157 this->buf[this->pos_read] = fixed;
162 /* check MIDI command length */
163 if (command & 0x80) {
164 midi_length = midibuf_message_length(command);
165 this->command_prev = command;
167 if (this->command_prev > 0) {
168 int midi_length_prev =
169 midibuf_message_length(this->command_prev);
171 if (midi_length_prev > 1) {
172 midi_length = midi_length_prev - 1;
180 if (midi_length < 0) {
181 /* search for end of message */
182 if (length < length1) {
183 /* no buffer wraparound */
184 for (i = 1; i < length; ++i)
185 if (this->buf[this->pos_read + i] & 0x80)
190 /* buffer wraparound */
191 length2 = length - length1;
193 for (i = 1; i < length1; ++i)
194 if (this->buf[this->pos_read + i] & 0x80)
200 for (i = 0; i < length2; ++i)
201 if (this->buf[i] & 0x80)
204 midi_length = length1 + i;
208 if (midi_length == length)
209 midi_length = -1; /* end of message not found */
212 if (midi_length < 0) {
214 return 0; /* command is not yet complete */
216 if (length < midi_length)
217 return 0; /* command is not yet complete */
219 length = midi_length;
222 if (length < length1) {
223 /* no buffer wraparound */
224 memcpy(data + repeat, this->buf + this->pos_read, length);
225 this->pos_read += length;
227 /* buffer wraparound */
228 length2 = length - length1;
229 memcpy(data + repeat, this->buf + this->pos_read, length1);
230 memcpy(data + repeat + length1, this->buf, length2);
231 this->pos_read = length2;
235 data[0] = this->command_prev;
238 return length + repeat;
241 int line6_midibuf_ignore(struct midi_buffer *this, int length)
243 int bytes_used = line6_midibuf_bytes_used(this);
245 if (length > bytes_used)
248 this->pos_read = (this->pos_read + length) % this->size;
253 void line6_midibuf_destroy(struct midi_buffer *this)