I think I have this figured out but I would like a second opinion from
someone who unlike myself paid attention in math class. (I was talking to
Maureen Valente.)
I'm trying to port an S/390 assembler routine to Visual Basic. VB has no
shift operators. I'm trying to simulate SRL R6,8
No need to know Visual Basic, just pretend the following is pseudo-code. R6
is defined as a signed, 32-bit (31-bit in 390-speak) integer. The VB seems
to work correctly; I'm not asking for VB help. I'd just like any of the
mathematicians on the list to tell me if my logic, especially for negative
values, is correct. I'm worried that I may have missed some boundary
condition. (This code could be shortened to one line, but I did it this way
to make the logic and the debugging clearer.)
' Simulate a shift right logical 8
If R6 >= 0 Then
R6 = R6 \ 256 ' \ is integer division
Else
R6 = R6 \ 256 ' \ is integer division
R6 = R6 - 1
R6 = R6 And &HFFFFFF ' Equivalent to S/390 X'FFFFFF'
End If
Thanks,
Charles Mills
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