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warning in doc about problems when using long + R0/R1 together

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Irmen de Jong
2025-10-11 15:36:57 +02:00
parent 07bb5c36bd
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2 changed files with 7 additions and 5 deletions
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docs/source/variables.rst
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@@ -248,8 +248,13 @@ to be done on word values, and don't want to explicitly have to cast everything
long value as an unsigned 32 bits value just fine.
Operations on long integers take a lot of instructions on 8 bit cpu's so code that uses them
a lot will be much slower than when you restrict yourself to 8 or 16 bit values. Use long values sparingly.
**Several operations on long values require the use of the R0 and R1 virtual register as temporary storage**
.. danger::
**longs and R0/R1**:
**Many operations on long values require the use of the R0 and R1 virtual register as temporary storage**
so if you are working with long values, you should assume that the contents of R0 and R1 are destroyed.
**Using R0 or R1 in expressions that work with longs, will probably give a corrupted result, without
a warning of the compiler!** It is strongly advised to *not* use R0/R1 at all when dealing with longs.
Booleans