diff options
Diffstat (limited to 'sound/usb/line6/midibuf.c')
| -rw-r--r-- | sound/usb/line6/midibuf.c | 252 |
1 files changed, 252 insertions, 0 deletions
diff --git a/sound/usb/line6/midibuf.c b/sound/usb/line6/midibuf.c new file mode 100644 index 000000000..c931d4880 --- /dev/null +++ b/sound/usb/line6/midibuf.c @@ -0,0 +1,252 @@ +/* + * Line 6 Linux USB driver + * + * Copyright (C) 2004-2010 Markus Grabner (grabner@icg.tugraz.at) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation, version 2. + * + */ + +#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; +} |