1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
|
<chapter id="OrchTop">
<title>Syntax of the Orchestra</title>
<para>
The Csound orchestra (.orc) or the <emphasis><CsInstruments></emphasis> section of a csd file, contains:
<itemizedlist>
<listitem>
<para>A <link linkend="OrchHeader"><citetitle>header section</citetitle></link>, which specifies global options for instrument performance</para>
</listitem>
<listitem>
<para>A list of <link linkend="OrchUDO"><citetitle>User defined opcodes</citetitle></link> and <link linkend="OrchIblock"><citetitle>instrument blocks</citetitle></link> containing UDO and instrument definitions.</para>
</listitem>
</itemizedlist>
</para>
<para>
The orchestra header, instrument blocks, and UDOs contain <emphasis>Orchestra statements</emphasis>. An <emphasis>orchestra statement</emphasis> in Csound has the format:
<synopsis>
label: <returnvalue>result</returnvalue> <function>opcode</function> <parameter>argument1</parameter>, <parameter>argument2</parameter>, <parameter>...</parameter> ;comments
</synopsis>
</para>
<para>
The label is optional and identifies the basic statement that follows as the potential target of a go-to operation (see <link linkend="ControlPgmctl"><citetitle>Program Flow Control</citetitle></link>). A label has no effect on the statement per se.
</para>
<para>
Depending on their function, some opcodes produce no output, so they have no result value. Others take no arguments and only produce a result.
</para>
<para>
Every orchestra statement must be on a single line, however long lines can be wrapped to a new line using the '\' character. This character indicates that the next line is part of the current one, this way you can split a line for easier reading, like this:
<programlisting>
a2 <emphasis role="opc">oscbnk</emphasis> kcps, 1.0, kfmd1, 0.0, 40, 203, 0.1, 0.2, kamfr, kamfr2, 148, \
0, 0, 0, 0, 0, 0, -1, \
kfnum, 3, 4</programlisting>
</para>
<para>
Comments are optional and are for the purpose of letting the user
document his orchestra code. Comments begin with a semicolon (;)
or // and extend to the end of the line. Comments can optionally be in C-style, spanning multiple lines like this:
<programlisting>
<emphasis role="comment">/* Anything in here --------
is a comment which can span
several lines --------- */</emphasis></programlisting>
</para>
<para>
The remainder (result, opcode, and arguments) form the basic statement. This also is optional, i.e. a line may have only a label or comment or be entirely blank. If present, the basic statement must be complete on one line, and is terminated by a carriage return and line feed.
</para>
<para>
The opcode determines the operation to be performed; it usually takes some number of input values (or arguments, with a maximum value of about 800); and it usually has a result field variable to which it sends output values at some fixed rate. There are four possible rates:
<orderedlist numeration="arabic">
<listitem>
<para>once only, at orchestra setup time (effectively a permanent assignment)</para>
</listitem>
<listitem>
<para>once at the beginning of each note (at initialization (init) time: i-rate)</para>
</listitem>
<listitem>
<para>once every performance-time control loop (perf-time control rate, or k-rate)</para>
</listitem>
<listitem>
<para>once each sound sample of every control loop (perf-time audio rate, or a-rate)</para>
</listitem>
</orderedlist>
</para>
&orchheader;
&orchiblock;
&orchstatemnt;
&orchkvar;
&orchexpress;
&orchdirfiles;
&orchnomen;
&orchmacros;<!--
&orchvarinit;-->
&orchnamedinstruments;
&orchUDO;
&orchtab;
&oviewfunctional;
&oviewserver;
</chapter>
|
