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emphasize index value size on pointer var indexing

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Irmen de Jong 2023-07-23 00:11:18 +02:00
parent 3bbc00cc8c
commit 4c6a2f5df9
2 changed files with 6 additions and 4 deletions
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5
docs/source/programming.rst
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@ -324,7 +324,8 @@ This way you can set the second character on the second row from the top like th
An uword variable can be used in limited scenarios as a 'pointer' to a byte in memory at a specific,
dynamic, location. You can use array indexing on a pointer variable to use it as a byte array at
a dynamic location in memory: currently this is equivalent to directly referencing the bytes in
memory at the given index. See also :ref:`pointervars_programming`
memory at the given index. In contrast to a real array variable, the index value can be the size of a word.
See also :ref:`pointervars_programming`
**LSB/MSB split word arrays:**
For (u)word arrays, you can make the compiler layout the array in memory as two separate arrays,
@ -445,7 +446,7 @@ without defining a memory mapped location, you can do so by enclosing the addres
This is the official syntax to 'dereference a pointer' as it is often named in other languages.
You can actually also use the array indexing notation for this. It will be silently converted into
the direct memory access expression as explained above. Note that this also means that unlike regular arrays,
the direct memory access expression as explained above. Note that unlike regular arrays,
the index is not limited to an ubyte value. You can use a full uword to index a pointer variable like this::
pointervar[999] = 0 ; set memory byte to zero at location pointervar + 999.

5
docs/source/syntaxreference.rst
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@ -414,7 +414,8 @@ directly access the memory. Enclose a numeric expression or literal with ``@(...
@($d020) = 0 ; set the c64 screen border to black ("poke 53280,0")
@(vic+$20) = 6 ; a dynamic expression to 'calculate' the address
The array indexing notation on a uword 'pointer variable' is syntactic sugar for such a direct memory access expression::
The array indexing notation on a uword 'pointer variable' is syntactic sugar for such a direct memory access expression,
and the index value can be larger than a byte in this case::
pointervar[999] = 0 ; equivalent to @(pointervar+999) = 0
@ -466,7 +467,7 @@ Syntax is familiar with brackets: ``arrayvar[x]`` ::
Note: you can also use array indexing on a 'pointer variable', which is basically an uword variable
containing a memory address. Currently this is equivalent to directly referencing the bytes in
memory at the given index. See :ref:`pointervars`
memory at the given index (and allows index values of word size). See :ref:`pointervars`
String
^^^^^^