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