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// SPDX-License-Identifier: GPL-2.0-only
/*
* Line 6 Linux USB driver
*
* Copyright (C) 2004-2010 Markus Grabner (grabner@icg.tugraz.at)
*/
#include <linux/slab.h>
#include "midibuf.h"
static int midibuf_message_length(unsigned char code)
{
int message_length;
if (code < 0x80)
message_length = -1;
else if (code < 0xf0) {
static const int length[] = { 3, 3, 3, 3, 2, 2, 3 };
message_length = length[(code >> 4) - 8];
} else {
/*
Note that according to the MIDI specification 0xf2 is
the "Song Position Pointer", but this is used by Line 6
to send sysex messages to the host.
*/
static const int length[] = { -1, 2, -1, 2, -1, -1, 1, 1, 1, 1,
1, 1, 1, -1, 1, 1
};
message_length = length[code & 0x0f];
}
return message_length;
}
static int midibuf_is_empty(struct midi_buffer *this)
{
return (this->pos_read == this->pos_write) && !this->full;
}
static int midibuf_is_full(struct midi_buffer *this)
{
return this->full;
}
void line6_midibuf_reset(struct midi_buffer *this)
{
this->pos_read = this->pos_write = this->full = 0;
this->command_prev = -1;
}
int line6_midibuf_init(struct midi_buffer *this, int size, int split)
{
this->buf = kmalloc(size, GFP_KERNEL);
if (this->buf == NULL)
return -ENOMEM;
this->size = size;
this->split = split;
line6_midibuf_reset(this);
return 0;
}
int line6_midibuf_bytes_free(struct midi_buffer *this)
{
return
midibuf_is_full(this) ?
0 :
(this->pos_read - this->pos_write + this->size - 1) % this->size +
1;
}
int line6_midibuf_bytes_used(struct midi_buffer *this)
{
return
midibuf_is_empty(this) ?
0 :
(this->pos_write - this->pos_read + this->size - 1) % this->size +
1;
}
int line6_midibuf_write(struct midi_buffer *this, unsigned char *data,
int length)
{
int bytes_free;
int length1, length2;
int skip_active_sense = 0;
if (midibuf_is_full(this) || (length <= 0))
return 0;
/* skip trailing active sense */
if (data[length - 1] == 0xfe) {
--length;
skip_active_sense = 1;
}
bytes_free = line6_midibuf_bytes_free(this);
if (length > bytes_free)
length = bytes_free;
if (length > 0) {
length1 = this->size - this->pos_write;
if (length < length1) {
/* no buffer wraparound */
memcpy(this->buf + this->pos_write, data, length);
this->pos_write += length;
} else {
/* buffer wraparound */
length2 = length - length1;
memcpy(this->buf + this->pos_write, data, length1);
memcpy(this->buf, data + length1, length2);
this->pos_write = length2;
}
if (this->pos_write == this->pos_read)
this->full = 1;
}
return length + skip_active_sense;
}
int line6_midibuf_read(struct midi_buffer *this, unsigned char *data,
int length)
{
int bytes_used;
int length1, length2;
int command;
int midi_length;
int repeat = 0;
int i;
/* we need to be able to store at least a 3 byte MIDI message */
if (length < 3)
return -EINVAL;
if (midibuf_is_empty(this))
return 0;
bytes_used = line6_midibuf_bytes_used(this);
if (length > bytes_used)
length = bytes_used;
length1 = this->size - this->pos_read;
/* check MIDI command length */
command = this->buf[this->pos_read];
if (command & 0x80) {
midi_length = midibuf_message_length(command);
this->command_prev = command;
} else {
if (this->command_prev > 0) {
int midi_length_prev =
midibuf_message_length(this->command_prev);
if (midi_length_prev > 1) {
midi_length = midi_length_prev - 1;
repeat = 1;
} else
midi_length = -1;
} else
midi_length = -1;
}
if (midi_length < 0) {
/* search for end of message */
if (length < length1) {
/* no buffer wraparound */
for (i = 1; i < length; ++i)
if (this->buf[this->pos_read + i] & 0x80)
break;
midi_length = i;
} else {
/* buffer wraparound */
length2 = length - length1;
for (i = 1; i < length1; ++i)
if (this->buf[this->pos_read + i] & 0x80)
break;
if (i < length1)
midi_length = i;
else {
for (i = 0; i < length2; ++i)
if (this->buf[i] & 0x80)
break;
midi_length = length1 + i;
}
}
if (midi_length == length)
midi_length = -1; /* end of message not found */
}
if (midi_length < 0) {
if (!this->split)
return 0; /* command is not yet complete */
} else {
if (length < midi_length)
return 0; /* command is not yet complete */
length = midi_length;
}
if (length < length1) {
/* no buffer wraparound */
memcpy(data + repeat, this->buf + this->pos_read, length);
this->pos_read += length;
} else {
/* buffer wraparound */
length2 = length - length1;
memcpy(data + repeat, this->buf + this->pos_read, length1);
memcpy(data + repeat + length1, this->buf, length2);
this->pos_read = length2;
}
if (repeat)
data[0] = this->command_prev;
this->full = 0;
return length + repeat;
}
int line6_midibuf_ignore(struct midi_buffer *this, int length)
{
int bytes_used = line6_midibuf_bytes_used(this);
if (length > bytes_used)
length = bytes_used;
this->pos_read = (this->pos_read + length) % this->size;
this->full = 0;
return length;
}
void line6_midibuf_destroy(struct midi_buffer *this)
{
kfree(this->buf);
this->buf = NULL;
}
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