6.1.9.34 Org Directive

The ORG directive changes the value of the location counter within the current psect.

Note: The much-abused ORG directive moves the location counter to an offset relative to the base address of the current psect, not to an absolute address. Only if the psect in which this directive is placed is marked with the abs and ovrld flags will the directive argument represent an absolute address. To place objects at an absolute address, place them in a psect of their own and link this psect at the required address using the linker's -P option (see P: Position Psect). The ORG directive is not commonly required in programs.

The argument to ORG must be either an absolute value, or a value referencing the current psect. In either case, the current location counter is set to the value determined by the argument. It is not possible to move the location counter backward. For example:

ORG 100h

will move the location counter to the beginning of the current psect plus 0x100. The actual location will not be known until link time. If the ORG directive is within a psect that has multiple components in the same module, the offset is calculated from the start of the psect, once all the psect components with the same name have been collated. For example, in the following:

psect text,class=CODE,delta=2
begin:
    btfsc status,2
    ...

psect text,class=CODE,delta=2
next:
ORG    200h
    movlw   20

the movlw instruction will be placed 0x200 words after the label begin, not 0x200 words after the label next. The offset imposed by this directive is not affected by psects with the same name in other modules.

In order to use the ORG directive to set the location counter to an absolute value, the directive must be used from within an absolute, overlaid psect. For example:

PSECT absdata,abs,ovrld
ORG 50h
;this is guaranteed to reside at address 50h