Offset Registers - Motorola MVME167 Series Installation Manual

Note

Offset Registers

Eight pseudo-registers (R0 through R7) called offset registers are
used to simplify the debugging of relocatable and position-
independent modules. The listing files in these types of programs
usually start at an address (normally 0) that is not the one at which
they are loaded, so it is harder to correlate addresses in the listing
with addresses in the loaded program. The offset registers solve
this problem by taking into account this difference and forcing the
display of addresses in a relative address+offset format. Offset
registers have adjustable ranges and may even have overlapping
ranges. The range for each offset register is set by two addresses:
base and top. Specifying the base and top addresses for an offset
register sets its range. In the event that an address falls in two or
more offset registers' ranges, the one that yields the least offset is
chosen.
Note
In commands with range specified as addr del addr, and
with size option W or L chosen, data at the second
(ending) address is acted on only if the second address
is a proper boundary for a word or longword,
respectively.
Relative addresses are limited to 1MB (5 digits),
regardless of the range of the closest offset register.
Entering Debugger Command Lines
5
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