General Music S2 Turbo, Руководство пользователя

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VI
APPENDIX
MIDI S
YSTEM
E
XCLUSIVE
C
ODE
I
NTERFACE
Introduction
MSECI (Midi System Exclusive Code Interface) is a
tool which permits a full operational interface with
other devices (Host computer, other GENERALMUSIC
device, etc.).
The user can access many resources contained in
GENERALMUSIC devices (files, edit structures, glo-
bal structures).
MSECI permits the programmer to write software for
many features, such as Machine Backup, Host Edit
Interface, etc..
An expert programmer with a good knowledge of the
uses of MSECI can write an excellent software for the
complete control of GENERALMUSIC devices.
Communications are achieved using MMA standard simi-
lar protocol.
In this document, all software examples are written in C
language and the italic characters are identifiers defined
in include files.
General Overview
MSECI consists of three parts:
1) File Functions
Here you will find the commands for a low level internal
file access.
The use of these commands are recommended for expert
programmers, because their incorrect use can damage
the internal file structure. However, File Functions aren’t
often useful.
2) Edit Functions
Here you will find the commands to access internal data
structures which can be edited.
To write a software program which performs external
editing functions, the programmer must be acquainted
with the specific internal edit structures, which can
differ from one GENERALMUSIC device to another.
3) Device Commands
In this part you will find commands for a general access
to the internal system.
The use of these commands is a valid alternative for
internal file access and their use is recommended.
This is an example of a general MSECI string:
F0 midi system exclusive identifier
2F GENERAL MUSIC exclusive code
fc f = function number (0-7) c=channel(0-F)
ss ss = subfunction (0-6F, 70-7F reserved)
rc rc = request channel(0-F)
..
.. data
..
cc cc=checksum if implemented
F7 end midi system exclusive
MSECI also includes a series of HANDSHAKE com-
mands.
A special conversion mode, from 8 bit to 7 bit MIDI
data, is used for binary data transmission, in which 7
real bytes are converted to 8 MIDI bytes, known as an
OCTECT (fig.1,ex.1,ex.2).
When the above conversion is performed in reverse, the
receiving algorithm must be written with care, because
the data packet is a finite number of octects and the
number of received bytes can be more than the real bytes
transmitted, therefore, the receiver must refer to the
data header for the exact number of bytes.
The function and subfunction identifiers are defined in
the include file “sys_id.h”.
Fig. 1: 8 to 7 bit conversion