Why do we use "drop"? What does "using" do?
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Answer / mike m
USING tells the assembler what your base reg. will be at
that point in the code.
DROP says to stop using the register coded on the DROP
instruction
| Is This Answer Correct ? | 12 Yes | 2 No |
Answer / phil
neither DROP nor USING affect the register contents.
Once a register has been loaded with the address of a piece
of storage, the using statement can be used to 'map' that
storage against a set of labels defining the layout of that
storage e.g. a DSECT. Then whenever one of those labels is
referenced in the code, in moves etc, the assembler resolves
the relative address as a particular displacement from the
absolute address in the register. The DROP instruction
removes the relationship between the labels and the register
and renders subsequent references to those labels as
unresolvable, giving rise to errors at assembly (compile)time.
Typically the DROP instruction will be used to allow use of
the register for another purpose, e.g. address a different
bit of storage via a using staement on second DSECT without
the risk of corrupting that data via moves referencing the
original DSECT.
| Is This Answer Correct ? | 9 Yes | 0 No |
Answer / ajay kuriyal
to be more precise , using maps the register with the dsect
and drop unmapped or disolve the mapping of register with
the dsect
| Is This Answer Correct ? | 5 Yes | 1 No |
Answer / guest
Using is to map the addressablity for a table and drop used
to drop the addresability of a register. (to remove the
addressability)
| Is This Answer Correct ? | 1 Yes | 1 No |
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