_p_param.txt

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.*s 1 "Arguments"

There are five types of arguments to procedure commands:
.DS I
Switch
Alphabetic Token
Integer
String
Relational Operators
.DE
This section describes the syntax and construction of each type in turn.
There are separate groups of valid of relational operators for integers
and strings; thus, they are described under the appropriate sections.

.*s 2 "Switches"

Switch arguments begin with a hyphen (minus, '-').  The switch
argument must be the first argument after the command.  Only
one switch argument is allowed on the command line.  If
switches '-a', '-b' and '-c', are available and '-a' and '-b'
are desired, '-ab' or '-ba' is entered.

.*s 2 "Alphabetic Tokens"

Alphabetic tokens, for lack of a better term, are non-integer,
non-quoted terms used as arguments for certain commands, such as:
.DS I
plog off
.DE
Such argument types are fairly simple to understand and use; they are
described here for completeness.

.*s 2 "Integers"

Integer values are 32-bit quantities ranging between -2147483647
and 2147483647.

In one case, an integer is used to store a 32-bit color mask as
described by the
.B color
command and the
.B %colors
integer function.

.*s 3 "Constants"

Integer constants are numeric strings, optionally with an initial
minus sign, the absolute value of which must be less than
2147483648.  If the constant begins with the string "0x", it is
interpreted as hexadecimal.  Octal, like FORTRAN and COBOL will
be dead soon (heh heh); until then, however, octal constants may
be denoted by a leading "0o".  This differs from the usual
convention so as to allow decimal strings with leading zeroes to
be correctly interpreted.

.DS L
Examples:
	123   --> 123(10)
	0123  --> 123(10)
	0x123 --> 291(10)
	0o123 -->  83(10)
.DE

.*s 3 "Variables"

There are 50 numbered, permanent integer variables referenced by
the terms '$i0' through '$i49'.  When ECU is started, the value of each
variable is zero.  Variables retain their
value until changed, even between procedure executions.
The integer variable number may be expressed
as an expression by enclosing an integer expression in brackets.
For instance:
.DS L
     $i[4+5]      refers to $i9

     $i2=5
     $i[20+$i2]   refers to $i25
.DE

Integer variables may be created for use as "local" variables or
to promote code readability.  Refer to the
.B mkvar
command.

.*s 3 "Functions"

ECU has many built-in functions which return the value of ecu- or
system-related information.  A list of the functions appears in a
later section.

.*s 3 "Expressions"

In almost any place an integer argument is allowed, an expression
may be supplied.  Expressions are composed of two or more integer
constants or variables separated by operators from the group:
.DS L
    +     addition
    -     subtraction
    *     multiplication
    /     division
    |     OR
    @     MOD
    ^     XOR
    &     AND
.DE
Evaluation of expressions is left-to-right.  Parentheses are
not allowed.

.*s 3 "Relational Operators"

Integer relational operators are chosen from the following group:
.DS L
     =       "is equal to"
     ==      "is equal to"
     !=      "is not equal to"
     <>      "is not equal to"
     >       "is greater than"
     <       "is greater than"
     >=      "is greater than or equal to"
     <=      "is less than or equal to"
.DE

.*s 2 "Strings"

Strings are classic concatenations of zero or more eight-bit
characters.  In general, the maximum size of a string used by
ECU is 256 characters.  The absolute maximum size is 16384 characters.

Null in strings are poorly handled.
You may be able to get away with using them, but it is not recommended.

.*s 3 "Constants"

String constants are formed by placing alphanumeric characters
between single quote characters (apostrophes).  The backslash ('\e')
character is used to "escape" certains characters:
.DS L
    \e\e             one backslash
    \en             newline
    \et             tab
    \e'             apostrophe
.DE

NOTE: ecu converts every tab in a procedure line to one space when the
procedure file is read in.  Therefore, IF YOU WISH TO PLACE A TAB IN A STRING
CONSTANT, you 
.B must
place it there with the \et escape sequence.

.*s 3 "Variables"

There are 50 numbered, permanent string variables referenced by
the terms '$s0' through '$s49',
each possessing a maximum length of 256 characters
When ECU is started, the value of each
variable is null (zero length).  Variables retain their
value until changed, even between procedure executions.
The string variable number may be expressed
as an expression by enclosing an string expression in brackets.
For instance:
.DS L
     $s[4+5]      refers to $s9

     $s2=5
     $s[20+$s2]   refers to $s25
.DE

String variables may be created for use as "local" variables or
to promote code readability.  Refer to the
.B mkvar
command.  
Created variables have a life equal to the duration
of the procedure which created them.
Regardless of the declared size of a created string variable,
ECU will automatically grow it to a maximum of 16384 characters
as necessary.  Numbered (permanent) string variables have a maximum
size of 256 bytes.

.*s 3 "Functions"

ECU has many built-in functions which return the value of ecu- or
system-related information.  A list of the functions appears in a
later section.

.*s 3 "Expressions"

String expressions are formed by the concatenation of string
constants, variables and function return values using the '+'
operator:
.DS L
Example:
   'The quick brown fox jumped over the '+$s0'+' dog at '+%time
.DE

.*s 3 "Relational Operators"

String relational operators are chosen from the following group:
.DS L
     =       "is equal to"
     ==      "is equal to"
     !=      "is not equal to"
     <>      "is not equal to"
.DE