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Old 22 July 2019, 15:57   #1
Soundy
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Strange indirect addressing with index

Hi,
Check the selected line in the below pic.
A2(=c4f3a4) + D2 (=9e92) should be c59236. But WinUAE computes c49236. So the A2+D2.W operation is clamped to 16 bits?
I thought all address computations were sign extended. What did I do wrong?
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Old 22 July 2019, 16:26   #2
npomarede
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Quote:
Originally Posted by Soundy View Post
Hi,
Check the selected line in the below pic.
A2(=c4f3a4) + D2 (=9e92) should be c59236. But WinUAE computes c49236. So the A2+D2.W operation is clamped to 16 bits?
I thought all address computations were sign extended. What did I do wrong?
Hi
WinUAE is correct. D2 is 16 bits and is signed extended.
9e92 has bit 15=1, so it's will be extended to a negative number -616e


And c4f3a4 - 616e is c49236 as reported by WinUae debugger



Nicolas
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Old 22 July 2019, 16:41   #3
Soundy
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Thanks Nicolas!
Stupid me Yeah, indeed any index higher than 32767 deserves a An+Dn.L instead of An+Dn.W even though it fits on 16 bits….
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Old 23 July 2019, 10:05   #4
Tomislav
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I suggest you to use command line debugger ("xx" command to change debugger). GUI debugger is not supported and it is older than command line debugger.
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