| /* |
| * Line6 Linux USB driver - 0.8.0 |
| * |
| * Copyright (C) 2004-2009 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 "config.h" |
| |
| #include <linux/slab.h> |
| |
| #include "midibuf.h" |
| |
| |
| static int midibuf_message_length(unsigned char code) |
| { |
| if(code < 0x80) |
| return -1; |
| else if(code < 0xf0) { |
| static const int length[] = { 3, 3, 3, 3, 2, 2, 3 }; |
| return length[(code >> 4) - 8]; |
| } |
| else { |
| /* |
| Note that according to the MIDI specification 0xf2 is the "Song Position |
| Pointer", but this is used by Line6 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 }; |
| return length[code & 0x0f]; |
| } |
| } |
| |
| void midibuf_reset(struct MidiBuffer *this) |
| { |
| this->pos_read = this->pos_write = this->full = 0; |
| this->command_prev = -1; |
| } |
| |
| int midibuf_init(struct MidiBuffer *this, int size, int split) |
| { |
| this->buf = (unsigned char *)kmalloc(size, GFP_KERNEL); |
| |
| if (this->buf == NULL) |
| return -ENOMEM; |
| |
| this->size = size; |
| this->split = split; |
| midibuf_reset(this); |
| return 0; |
| } |
| |
| void midibuf_status(struct MidiBuffer *this) |
| { |
| printk("midibuf size=%d split=%d pos_read=%d pos_write=%d full=%d command_prev=%02x\n", |
| this->size, this->split, this->pos_read, this->pos_write, this->full, this->command_prev); |
| } |
| |
| static int midibuf_is_empty(struct MidiBuffer *this) |
| { |
| return (this->pos_read == this->pos_write) && !this->full; |
| } |
| |
| static int midibuf_is_full(struct MidiBuffer *this) |
| { |
| return this->full; |
| } |
| |
| int midibuf_bytes_free(struct MidiBuffer *this) |
| { |
| return |
| midibuf_is_full(this) ? |
| 0 : |
| (this->pos_read - this->pos_write + this->size - 1) % this->size + 1; |
| } |
| |
| int midibuf_bytes_used(struct MidiBuffer *this) |
| { |
| return |
| midibuf_is_empty(this) ? |
| 0 : |
| (this->pos_write - this->pos_read + this->size - 1) % this->size + 1; |
| } |
| |
| int midibuf_write(struct MidiBuffer *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 = 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 midibuf_read(struct MidiBuffer *this, unsigned char *data, int length) |
| { |
| int bytes_used; |
| int length1, length2; |
| int command; |
| int midi_length; |
| int repeat = 0; |
| int i; |
| |
| if(length < 3) |
| return -EINVAL; /* we need to be able to store at least a 3 byte MIDI message */ |
| |
| if(midibuf_is_empty(this)) |
| return 0; |
| |
| bytes_used = 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 > 0) { |
| 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 midibuf_ignore(struct MidiBuffer *this, int length) |
| { |
| int bytes_used = 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; |
| } |
| |
| int midibuf_skip_message(struct MidiBuffer *this, unsigned short mask) |
| { |
| int cmd = this->command_prev; |
| |
| if((cmd >= 0x80) && (cmd < 0xf0)) |
| if((mask & (1 << (cmd & 0x0f))) == 0) |
| return 1; |
| |
| return 0; |
| } |
| |
| void midibuf_destroy(struct MidiBuffer *this) |
| { |
| kfree(this->buf); |
| this->buf = NULL; |
| } |