Campbell CR800 Especificaciones descargar pdf (Pagina 107)

Section 4. CRBasic - Native Language Programming

The CR800 expression evaluator evaluates the expression, X>=5, and returns -

1, if the expression is true, and 0, if the expression is false.

W=(X>Y)

will set W equal to -1 if X>Y or will set W equal to 0 if X<=Y.

The CR800 uses -1 rather than some other non-zero number because the and

and or operators are the same for logical statements and binary bitwise

comparisons (see and and or in Section 8). The number -1 is expressed in

binary with all bits equal to 1, the number 0 has all bits equal to 0. When -1 is

anded with any other number the result is the other number, ensuring that if the

other number is non-zero (true), the result will be non-zero

4.7 Flags

While any variable can be used as a flag as far as logical tests in CRBasic are

concerned, it is best to use Boolean variables. If the value of the variable is

non-zero the flag is high. If the value of the variable is 0 the flag is low

(Section 4.6). Boolean variables can only have one of two values, true (-1) or

false (0).

4.8 Parameter Types

Instruction parameters allow different types of inputs. These types are listed

below and specifically identified in the description of the parameter in the

following sections or in CRBasic help.

Constant

Variable

Variable or Array

Constant, Variable, or Expression

Constant, Variable, Array, or Expression

Name

Name or list of Names

Variable, or Expression

Variable, Array, or Expression

Table 4.8-1 lists the maximum length and allowed characters for the names for

Variables, Arrays, Constants, etc.

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Campbell CR800 Especificaciones Pagina 107