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Implement ds align[alignment, offset] (#1181)

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Rangi
2023-11-21 17:57:47 -05:00
committed by GitHub
parent 6f0ffcf3e1
commit 46e29de66f
17 changed files with 148 additions and 17 deletions
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42
man/rgbasm.5
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@@ -681,14 +681,14 @@ Place the section at an address whose
.Ar align
least-significant bits are equal to
.Ar offset .
(Note that
Note that
.Ic ALIGN Ns Bq Ar align
is a shorthand for
.Ic ALIGN Ns Bq Ar align , No 0 ) .
.Ic ALIGN Ns Bq Ar align , No 0 .
This option can be used with
.Bq Ar addr ,
as long as they don't contradict eachother.
It's also possible to request alignment in the middle of a section, see
as long as they don't contradict each other.
It's also possible to request alignment in the middle of a section; see
.Sx Requesting alignment
below.
.El
@@ -869,7 +869,7 @@ or
.Ic ROMX .
.El
.Pp
Different declarations of the same unionized section are not appended, but instead overlaid on top of eachother, just like
Different declarations of the same unionized section are not appended, but instead overlaid on top of each other, just like
.Sx Unions .
Similarly, the size of an unionized section is the largest of all its declarations.
.Ss Section fragments
@@ -1433,6 +1433,27 @@ In ROM sections, it will be filled with the value passed to the
.Fl p
command-line option, except when using overlays with
.Fl O .
.Pp
Instead of an exact number of bytes, you can specify
.Ic ALIGN Ns Bq Ar align , offset
to allocate however many bytes are required to align the subsequent data.
Thus,
.Sq Ic DS ALIGN Ns Bo Ar align , offset Bc , No ...
is equivalent to
.Sq Ic DS Ar n , No ...
followed by
.Sq Ic ALIGN Ns Bq Ar align , offset ,
where
.Ar n
is the minimum value needed to satisfy the
.Ic ALIGN
constraint (see
.Sx Requesting alignment
below).
Note that
.Ic ALIGN Ns Bq Ar align
is a shorthand for
.Ic ALIGN Ns Bq Ar align , No 0 .
.Ss Defining constant data in ROM
.Ic DB
defines a list of bytes that will be stored in the final image.
@@ -2137,6 +2158,17 @@ Note that
.Ic ALIGN Ar align
is a shorthand for
.Ic ALIGN Ar align , No 0 .
.Pp
There may be times when you don't just want to specify an alignment constraint at the current location, but also skip ahead until the constraint can be satisfied.
In that case, you can use
.Ic DS ALIGN Ns Bq Ar align , offset
to allocate however many bytes are required to align the subsequent data.
.Pp
If the constraint cannot be met by skipping any amount of space, an error is produced.
Note that
.Ic ALIGN Ns Bq Ar align
is a shorthand for
.Ic ALIGN Ns Bq Ar align , No 0 .
.Sh SEE ALSO
.Xr rgbasm 1 ,
.Xr rgblink 1 ,