Subject:
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Re: programming help.
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Sat, 31 Oct 1998 03:17:24 GMT
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Original-From:
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Eric Noyau <noyau@apple.com=spamcake=>
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Viewed:
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1732 times
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At 10:34 AM 10/31/98 , Edmund wrote:
>
> hello
>
> can someone please tell me what does the following command line mean?
>
> bit_set(0x0e, 1 << (4 + motor));
>
> i know that 0x0e refers to memory location $0E but how does bit_set
> work? is it similar to poke? and more importantly, what operation
> does '1 << (4 + motor)' perform?
>
> any help will be appreciated. thanks.
>
>
In binary 1 is represented by 0000-0001
1 << 1 is 0000-0010 aka 2
1 << 2 is 0000-0100 aka 4
1 << 3 is 0000-1000 aka 8
You get the idea? x << y means slide x to the left y times.
motor is probably a number between 0 and 3. 4+motor is then a number between 4 and 7.
so, to go back to your example the result of 1<<(4+motor) is one of:
1000-0000
0100-0000
0010-0000
0001-0000
And my guess is that bit_set(address, value) is equivalent to poke(address, peek(address) | value). I don't have any documentation here, so I don't know what is stored in 0x0e, but it could be the place where you turn the motors on and off. And the code you are looking at is turning a motor on without touching the other motors.
-- Eric
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Message is in Reply To:
 | | programming help.
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| hello can someone please tell me what does the following command line mean? bit_set(0x0e, 1 << (4 + motor)); i know that 0x0e refers to memory location $0E but how does bit_set work? is it similar to poke? and more importantly, what operation does (...) (26 years ago, 31-Oct-98, to lugnet.robotics.handyboard)
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