sys/dev/midictl.h

   1 /* $NetBSD: midictl.h,v 1.2 2006/06/30 13:56:25 chap Exp $ */
   2
   3 /*-
   4  * Copyright (c) 2006 The NetBSD Foundation, Inc.
   5  * All rights reserved.
   6  *
   7  * This code is derived from software contributed to The NetBSD Foundation
   8  * by Chapman Flack.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29  * POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 #ifndef _SYS_DEV_MIDICTL_H_
  33 #define _SYS_DEV_MIDICTL_H_
  34
  35 /*
  36  * General support for MIDI controllers, registered parameters, and
  37  * nonregistered parameters. It interprets MIDI messages that update
  38  * these values, maintains the associated state, and provides an API
  39  * for obtaining the current value of any controller or parameter and
  40  * tracking changes to it.
  41  *
  42  * One function provides the interface for message parsing. When a message
  43  * is received, once it has been determined to be a MIDI_CTL_CHANGE message,
  44  * simply call midictl_change(&mc, chan, ctlval) where chan is the channel
  45  * extracted from the first byte, and ctlval points to the remaining two
  46  * bytes of the message received.
  47  *
  48  * The API for reading the state is equally simple. Use
  49  * midictl_read(&mc, chan, ctlr, dflt)
  50  * midictl_rpn_read(&mc, chan, rpn, dflt)
  51  * midictl_nrpn_read(&mc, chan, nrpn, dflt)
  52  * to read the current value of controller #ctlr, RP #rpn, or NRP #nrpn,
  53  * respectively. (For 14-bit controllers, use the MSB number as ctlr, not
  54  * the LSB number.) You get the complete current value; for 14-bit controllers
  55  * and parameters you get a single 14-bit integer without fussing about the
  56  * multiple MIDI messages needed to set it. If you read a controller or
  57  * parameter that no MIDI message has yet written, you get back the value dflt.
  58  * If you read one whose MSB or LSB only has been written, you get what you
  59  * would get if the value had been dflt before the write.
  60  *
  61  * The functions may be called from any context but reentrant calls operating
  62  * on the same midictl are unsupported, with one exception: calls back into
  63  * midictl from a notify handler it has called are permitted. If you are
  64  * calling midictl_change in a driver function called by midi(4), you are ok
  65  * as midi(4) itself serializes its calls into the driver. For other uses,
  66  * avoiding reentrant calls is up to you.
  67  *
  68  * A strict division of labor limits complexity. This module knows as little
  69  * about the meanings of different MIDI parameters and controllers as possible
  70  * to do its job: it knows which controllers are overloaded to serve as
  71  * channel mode messages, and which are overloaded to provide access to the
  72  * RPN and NRPN space. It knows which controllers are 14-bit, 7-bit, or 1-bit
  73  * according to the table online at midi.org. (All parameters are treated as
  74  * 14-bit.) It does not know or care about the specified default values;
  75  * client code is expected to know those defaults for whatever controls it
  76  * actually implements, and supply them when calling midictl_*read(). That
  77  * avoids the need for a large table of specified values for things most
  78  * clients will never read. A header file defining the official defaults could
  79  * be useful for clients to include for use when calling midictl_*read, but
  80  * is not part of this module. Reset All Controllers is simply handled by
  81  * forgetting controllers have been written at all, so the next read by
  82  * the client will return the client's supplied default.
  83  *
  84  * An incoming MIDI stream may refer to many controllers and parameters the
  85  * client does not implement. To limit memory use, messages are ignored by
  86  * default if they target a controller or parameter the client has never
  87  * read. To indicate which controllers/parameters it supports, the client
  88  * should simply read them when starting.
  89  *
  90  * Where the task is to generically process some MIDI stream without losing
  91  * data, accept_any_ctl_rpn can be set to 1 in the midictl structure, and
  92  * state will be kept for any incoming controller or RPN update. The separate
  93  * flag accept_any_nrpn enables the same behavior for nonregistered parameters.
  94  *
  95  * Whenever a change is made to any value for which state is being kept, the
  96  * notify function will be called with MIDICTL_CTLR, MIDICTL_RPN, or
  97  * MIDICTL_NRPN, the channel, and the controller, rp, or nrp number,
  98  * respectively. The controller number will never refer to the LSB of a 14-bit
  99  * controller. The new /value/ is not included; if the change is of interest,
 100  * the client reads the value and thereby supplies the default (which can still
 101  * be needed if the update is to half of a 14-bit value). The notify function
 102  * is also called, with appropriate evt codes, on receipt of channel mode
 103  * messages.
 104  *
 105  * Reset All Controllers:
 106  *
 107  * The Reset All Controllers message will cause this module to forget settings
 108  * for all controllers on the affected channel other than those specifically
 109  * excepted by MIDI RP-015. Registered and nonregistered parameters are not
 110  * affected. The notify function is then called with evt = MIDICTL_RESET.
 111  *
 112  * The client's response to MIDICTL_RESET should include reading all
 113  * controllers it cares about, to ensure (if the accept_any_ctl_rpn flag is not
 114  * set) that they will continue to be tracked. The client must also reset to
 115  * defaults the following pieces of channel state that are not managed by this
 116  * module, but required by RP-015 to be reset:
 117  *  Pitch Bend
 118  *  Channel Pressure
 119  *  Key Pressure (for all keys on channel)
 120  * The client does NOT reset the current Program.
 121  */
 122 #include <sys/midiio.h>
 123 #include <sys/stdint.h>
 124
 125 /*
 126  * Events that may be reported via a midictl_notify function.
 127  * Enum starts at 1<<16 so that enum|key can be used as a switch expression.
 128  * Key is 0 except where shown below.
 129  */
 130 typedef enum {
 131         MIDICTL_CTLR      = 1<<16,      /* key=ctlr */
 132         MIDICTL_RPN       = 2<<16,      /* key=rpn */
 133         MIDICTL_NRPN      = 3<<16,      /* key=nrpn */
 134         MIDICTL_RESET     = 4<<16,      /* Reset All Controllers received */
 135         MIDICTL_NOTES_OFF = 5<<16,      /* All Notes Off received */
 136         MIDICTL_SOUND_OFF = 6<<16,      /* All Sound Off received */
 137         MIDICTL_LOCAL     = 7<<16,      /* if (key) localIsOn else localIsOff */
 138         MIDICTL_MODE      = 8<<16       /* key=mode(1-4)? TBD unimplemented */
 139 } midictl_evt;
 140
 141 /*
 142  * midictl_notify(void *cookie, midictl_evt evt,
 143  *                uint_fast8_t chan, uint_fast16_t key)
 144  */
 145 typedef void
 146 midictl_notify(void *, midictl_evt, uint_fast8_t, uint_fast16_t);
 147
 148 typedef struct midictl_store midictl_store;
 149
 150 typedef struct {
 151         uint_fast8_t accept_any_ctl_rpn:1; /* 0 ==> ignore chgs for unqueried */
 152         uint_fast8_t accept_any_nrpn:1;    /* likewise for NRPNs */
 153         uint_fast8_t base_channel; /* set >= 16 to ignore any MODE messages */
 154         void *cookie;              /* this value will be passed to notify */
 155         midictl_notify *notify;
 156         /* */
 157         uint16_t rpn;
 158         uint16_t nrpn;
 159         midictl_store *store;
 160 } midictl;
 161
 162 extern void
 163 midictl_open(midictl *);
 164
 165 extern void
 166 midictl_close(midictl *);
 167
 168 /*
 169  * Called on receipt of a Control Change message. Updates the controller,
 170  * RPN, or NRPN value as appropriate. When updating a controller or RPN that
 171  * is defined in the spec as boolean, all values that by definition represent
 172  * false are coerced to zero. Fires the callback if a value of interest has
 173  * been changed.
 174  * ctlval: points to the second byte of the message (therefore, to a two-
 175  * byte array: controller number and value).
 176  * midictl_change(midictl *mc, uint_fast8_t chan, uint8_t *ctlval);
 177  */
 178 extern void
 179 midictl_change(midictl *, uint_fast8_t, uint8_t *);
 180
 181 /*
 182  * Read the current value of controller ctlr for channel chan.
 183  * If this is the first time querying this controller on this channel,
 184  * and accept_any_ctl_rpn is false, any earlier change message for it
 185  * will have been ignored, so it will be given the value dflt, which is
 186  * also returned, and future change messages for it will take effect.
 187  * If the controller has a two-byte value and only one has been explicitly set
 188  * at the time of the first query, the effect is as if the value had been
 189  * first set to dflt, then the explicitly-set byte updated.
 190  * midictl_read(midictl *mc, uint_fast8_t chan,
 191  *              uint_fast8_t ctlr, uint_fast16_t dflt);
 192  */
 193 extern uint_fast16_t
 194 midictl_read(midictl *, uint_fast8_t, uint_fast8_t, uint_fast16_t);
 195
 196 /*
 197  * As for midictl_read, but for registered parameters or nonregistered
 198  * parameters, respectively.
 199  */
 200 extern uint_fast16_t
 201 midictl_rpn_read(midictl *mc, uint_fast8_t, uint_fast16_t, uint_fast16_t);
 202 extern uint_fast16_t
 203 midictl_nrpn_read(midictl *mc, uint_fast8_t, uint_fast16_t, uint_fast16_t);
 204
 205 #endif /* _SYS_DEV_MIDICTL_H_ */