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More details on 8086 support

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Karol Stasiak 2019-06-15 01:43:46 +02:00
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docs/lang/x86disclaimer.md
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@ -79,6 +79,13 @@ as 8080's `DAD` changes only the carry flag, and 8086's `ADD` changes many flags
Luckily, this is not an issue with Millfork code, as the optimizer does not assume anything about flags after that instruction.
The proper sequence is `LAHF`/`ADD r1,r2`/`RCR SI,1`/`SAHF`/`RCL SI,1`, but it is obviously too slow.
* the converter translates the `INX` instruction (16-bit `INC` on Z80) to `INC`,
and similarly, the `DCX` instruction (16-bit `DEC` on Z80) to `DEC` ,
which may change behaviour of assembly code,
as 8080's `INX` and `DCX` don't change any flags, and 8086's `INC` and `DEC` change many flags.
Luckily, this is not an issue with Millfork code, as the optimizer does not assume anything about flags after that instruction.
The proper sequence is `LAHF`/`INC r` (or `DEC r`)/`SAHF`, but it is obviously too slow.
#### Register mapping
The registers are translated as following: