6.1.9.22 Global Directive

The GLOBAL identifier_list directive declares a list of comma-separated symbols. If the symbols are defined within the current module, they are made public. If the symbols are not defined in the current module, they are made references to public symbols with the same name that are defined in other modules. Thus, to use the same symbol in more than one module, the GLOBAL directive must be used multiple times: once in the module that defines the symbol to make that symbol public, and again in each module that uses the symbol, to allow that symbol to link in with the external definition.

In the following example, lab1 and lab2 are both defined in file1.S and made globally accessible. In file2.S, they are accessed.

;file1.S
#include <xc.inc>

GLOBAL  lab1,lab2
PSECT udata_bank2
lab1:
    DS      1
lab2:
    DS      2

;file2.S
#include <xc.inc>

GLOBAL  lab1,lab2
PSECT code
    movlw   0xfe
    BANKSEL 2
    movwf   BANKMASK(lab1)
    movwf   BANKMASK(lab2)

Only symbols that are marked as being globally accessible will be visible in debuggers, since there can be more than one local symbol in separate assembly modules with the same name. Thus, you might need to use the GLOBAL directive in order to watch symbols associated with variables.