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 Post subject: muls cycle count
PostPosted: Tue Feb 26, 2013 10:25 pm 
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Joined: Sun Feb 17, 2013 7:16 pm
Posts: 10
MOVE.L #$12345678, D1
MOVE.L #$12345678, D2
MULS.W D1, D2

That gives a cycle count of 50 for muls in easy68k, means n = 6. Comparing with the formula of winuae n would be 8.
0x5678 = 0101 0110 0111 1000
concatenate with a zero as lsb = 0 1010 1100 1111 0000 (17 bit)
I would count 8 ( 01, 10 ) changes too.


I am curious what is right?

0 1010 1100 1111 0000 = 01 - 01 - 01 -10 - 01 - 10 -> 6 changes
or
0 1010 1100 1111 0000 = 01 - 10 - 01 - 10 -01 -10 - 01 - 10 -> 8 changes


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 Post subject: Re: muls cycle count
PostPosted: Tue Feb 26, 2013 11:45 pm 
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Joined: Thu Dec 16, 2004 6:42 pm
Posts: 1036
Location: Monroe County Community College, Monroe Michigan, U.S.A.
n=8 is correct.

Thank you for the feedback.

The latest version of Sim68K calculates the time correctly.

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Prof. Kelly


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