FreeBSD/Linux Kernel Cross Reference
sys/dev/midictl.h

     /* $NetBSD: midictl.h,v 1.2 2006/06/30 13:56:25 chap Exp $ */
     
     /*-
      * Copyright (c) 2006 The NetBSD Foundation, Inc.
      * All rights reserved.
      *
      * This code is derived from software contributed to The NetBSD Foundation
      * by Chapman Flack.
      *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *        This product includes software developed by the NetBSD
     *        Foundation, Inc. and its contributors.
     * 4. Neither the name of The NetBSD Foundation nor the names of its
     *    contributors may be used to endorse or promote products derived
     *    from this software without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     * POSSIBILITY OF SUCH DAMAGE.
     */
    
    #ifndef _SYS_DEV_MIDICTL_H_
    #define _SYS_DEV_MIDICTL_H_
    
    /*
     * General support for MIDI controllers, registered parameters, and
     * nonregistered parameters. It interprets MIDI messages that update
     * these values, maintains the associated state, and provides an API
     * for obtaining the current value of any controller or parameter and
     * tracking changes to it.
     *
     * One function provides the interface for message parsing. When a message
     * is received, once it has been determined to be a MIDI_CTL_CHANGE message,
     * simply call midictl_change(&mc, chan, ctlval) where chan is the channel
     * extracted from the first byte, and ctlval points to the remaining two
     * bytes of the message received.
     *
     * The API for reading the state is equally simple. Use
     * midictl_read(&mc, chan, ctlr, dflt)
     * midictl_rpn_read(&mc, chan, rpn, dflt)
     * midictl_nrpn_read(&mc, chan, nrpn, dflt)
     * to read the current value of controller #ctlr, RP #rpn, or NRP #nrpn,
     * respectively. (For 14-bit controllers, use the MSB number as ctlr, not
     * the LSB number.) You get the complete current value; for 14-bit controllers
     * and parameters you get a single 14-bit integer without fussing about the
     * multiple MIDI messages needed to set it. If you read a controller or
     * parameter that no MIDI message has yet written, you get back the value dflt.
     * If you read one whose MSB or LSB only has been written, you get what you
     * would get if the value had been dflt before the write.
     *
     * The functions may be called from any context but reentrant calls operating
     * on the same midictl are unsupported, with one exception: calls back into
     * midictl from a notify handler it has called are permitted. If you are
     * calling midictl_change in a driver function called by midi(4), you are ok
     * as midi(4) itself serializes its calls into the driver. For other uses,
     * avoiding reentrant calls is up to you.
     *
     * A strict division of labor limits complexity. This module knows as little
     * about the meanings of different MIDI parameters and controllers as possible
     * to do its job: it knows which controllers are overloaded to serve as
     * channel mode messages, and which are overloaded to provide access to the
     * RPN and NRPN space. It knows which controllers are 14-bit, 7-bit, or 1-bit
     * according to the table online at midi.org. (All parameters are treated as
     * 14-bit.) It does not know or care about the specified default values;
     * client code is expected to know those defaults for whatever controls it
     * actually implements, and supply them when calling midictl_*read(). That
     * avoids the need for a large table of specified values for things most
     * clients will never read. A header file defining the official defaults could
     * be useful for clients to include for use when calling midictl_*read, but
     * is not part of this module. Reset All Controllers is simply handled by
     * forgetting controllers have been written at all, so the next read by
     * the client will return the client's supplied default.
     *
     * An incoming MIDI stream may refer to many controllers and parameters the
     * client does not implement. To limit memory use, messages are ignored by
     * default if they target a controller or parameter the client has never
     * read. To indicate which controllers/parameters it supports, the client
     * should simply read them when starting.
     *
     * Where the task is to generically process some MIDI stream without losing
     * data, accept_any_ctl_rpn can be set to 1 in the midictl structure, and
     * state will be kept for any incoming controller or RPN update. The separate
    * flag accept_any_nrpn enables the same behavior for nonregistered parameters.
    *
    * Whenever a change is made to any value for which state is being kept, the
    * notify function will be called with MIDICTL_CTLR, MIDICTL_RPN, or
    * MIDICTL_NRPN, the channel, and the controller, rp, or nrp number,
    * respectively. The controller number will never refer to the LSB of a 14-bit
    * controller. The new /value/ is not included; if the change is of interest,
    * the client reads the value and thereby supplies the default (which can still
    * be needed if the update is to half of a 14-bit value). The notify function
    * is also called, with appropriate evt codes, on receipt of channel mode
    * messages.
    * 
    * Reset All Controllers:
    *
    * The Reset All Controllers message will cause this module to forget settings
    * for all controllers on the affected channel other than those specifically
    * excepted by MIDI RP-015. Registered and nonregistered parameters are not
    * affected. The notify function is then called with evt = MIDICTL_RESET.
    *
    * The client's response to MIDICTL_RESET should include reading all
    * controllers it cares about, to ensure (if the accept_any_ctl_rpn flag is not
    * set) that they will continue to be tracked. The client must also reset to
    * defaults the following pieces of channel state that are not managed by this
    * module, but required by RP-015 to be reset:
    *  Pitch Bend
    *  Channel Pressure
    *  Key Pressure (for all keys on channel)
    * The client does NOT reset the current Program.
    */
   #include <sys/midiio.h>
   #include <sys/stdint.h>
   
   /*
    * Events that may be reported via a midictl_notify function.
    * Enum starts at 1<<16 so that enum|key can be used as a switch expression.
    * Key is 0 except where shown below.
    */
   typedef enum {
           MIDICTL_CTLR      = 1<<16,      /* key=ctlr */
           MIDICTL_RPN       = 2<<16,      /* key=rpn */
           MIDICTL_NRPN      = 3<<16,      /* key=nrpn */
           MIDICTL_RESET     = 4<<16,      /* Reset All Controllers received */
           MIDICTL_NOTES_OFF = 5<<16,      /* All Notes Off received */
           MIDICTL_SOUND_OFF = 6<<16,      /* All Sound Off received */
           MIDICTL_LOCAL     = 7<<16,      /* if (key) localIsOn else localIsOff */
           MIDICTL_MODE      = 8<<16       /* key=mode(1-4)? TBD unimplemented */
   } midictl_evt;
   
   /*
    * midictl_notify(void *cookie, midictl_evt evt,
    *                uint_fast8_t chan, uint_fast16_t key)
    */
   typedef void
   midictl_notify(void *, midictl_evt, uint_fast8_t, uint_fast16_t);
   
   typedef struct midictl_store midictl_store;
   
   typedef struct {
           uint_fast8_t accept_any_ctl_rpn:1; /* 0 ==> ignore chgs for unqueried */
           uint_fast8_t accept_any_nrpn:1;    /* likewise for NRPNs */
           uint_fast8_t base_channel; /* set >= 16 to ignore any MODE messages */
           void *cookie;              /* this value will be passed to notify */
           midictl_notify *notify;
           /* */
           uint16_t rpn;
           uint16_t nrpn;
           midictl_store *store;
   } midictl;
   
   extern void
   midictl_open(midictl *);
   
   extern void
   midictl_close(midictl *);
   
   /*
    * Called on receipt of a Control Change message. Updates the controller,
    * RPN, or NRPN value as appropriate. When updating a controller or RPN that
    * is defined in the spec as boolean, all values that by definition represent
    * false are coerced to zero. Fires the callback if a value of interest has
    * been changed.
    * ctlval: points to the second byte of the message (therefore, to a two-
    * byte array: controller number and value).
    * midictl_change(midictl *mc, uint_fast8_t chan, uint8_t *ctlval);
    */
   extern void
   midictl_change(midictl *, uint_fast8_t, uint8_t *);
   
   /*
    * Read the current value of controller ctlr for channel chan.
    * If this is the first time querying this controller on this channel,
    * and accept_any_ctl_rpn is false, any earlier change message for it
    * will have been ignored, so it will be given the value dflt, which is
    * also returned, and future change messages for it will take effect.
    * If the controller has a two-byte value and only one has been explicitly set
    * at the time of the first query, the effect is as if the value had been
    * first set to dflt, then the explicitly-set byte updated.
    * midictl_read(midictl *mc, uint_fast8_t chan,
    *              uint_fast8_t ctlr, uint_fast16_t dflt);
    */
   extern uint_fast16_t
   midictl_read(midictl *, uint_fast8_t, uint_fast8_t, uint_fast16_t);
   
   /*
    * As for midictl_read, but for registered parameters or nonregistered
    * parameters, respectively.
    */
   extern uint_fast16_t
   midictl_rpn_read(midictl *mc, uint_fast8_t, uint_fast16_t, uint_fast16_t);
   extern uint_fast16_t
   midictl_nrpn_read(midictl *mc, uint_fast8_t, uint_fast16_t, uint_fast16_t);
   
   #endif /* _SYS_DEV_MIDICTL_H_ */

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