Micah Carrick <piclist@mit.edu> wrote:

> An equate is just a way of defining constants which the compiler
> will know to replace the label with the defined constant value
> anywhere it sees it in the souce code. 
> 
> A Cblock actually allocates a block of RAM to store a value and
> can therefore be manipulated etc. 
> 
> Is this correct?

Micah:

No.

CBLOCK and EQU do the same thing: They assign constant values to 
symbols.  "Allocating a block of RAM" is a meaningless concept on the 
PIC; CBLOCK is just a syntax that makes the assignment of consecutive 
values easier, and makes it simpler to go back and insert or remove 
symbols from the list without having to change other lines of code.  

This:

        CBLOCK 20H
    REG1
    REG2,2
    REG3
        ENDC

is equivalent to this:

    POINTER SET 20
    REG1    EQU POINTER
    REG2    EQU REG1+1
    REG3    EQU REG2+2
    POINTER SET REG3+1

And this:

        CBLOCK
    REG4
    REG5,4
        ENDC

is the same as:

    REG4    EQU POINTER
    REG5    EQU REG4+1
    POINTER SET REG5+4

-Andrew

=== Andrew Warren -- aiw@cypress.com
=== Principal Design Engineer
=== Cypress Semiconductor Corporation
=== (but open to offers)
=== 
=== Opinions expressed above do not
=== necessarily represent those of
=== Cypress Semiconductor Corporation

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