Bitwise NOT? NOT! Not sure which way to convert this...

Oldbitcollector (Jeff)

I thought at first what I was trying to do is a bitwise NOT.. After scanning the Propeller Manual and a quick test, this isn't what I'm trying to accomplish.

If I've got a binary number that looks like this: 10010000
I need that number to look like this: 00001001

Bitwise NOT returns: 111101110 I'm trying to flip the number completely over.

Can someone tell me what type of bit shift I'm attempting here?

Thanks

Jeff

Ron Czapala

Oldbitcollector (Jeff) wrote: »

I thought at first what I was trying to do is a bitwise NOT.. After scanning the Propeller Manual and a quick test, this isn't what I'm trying to accomplish.

If I've got a binary number that looks like this: 10010000
I need that number to look like this: 000010001

Bitwise NOT returns: 111101110 I'm trying to flip the number completely over.

Can someone tell me what type of bit shift I'm attempting here?

Thanks

Jeff

I assume you mean 00001001 not 000010001 - you got nine bits there bud!

Oldbitcollector (Jeff)

yes.. corrected... Sorry, going a little cross-eyed working on this..

SRLM

Are you doing a right shift? Do you want to do a nibble swap?

Oldbitcollector (Jeff)

Ah Ha! Found it! (posting this for anyone discovering this thread via a Google search)

I needed to read a little further in.. Propeller Manual, Page 163.. Bitwise Reverse >< 8

Spin is just freak'n awesome..

Duane Degn

I forget what it's called but it's the "><" operator.

x ><= 8

Will flip reverse the last 8 bits.

Edit: You find it. Bitwise reverse. Yeah, that's what it's called.

Heater.

I'm not sure why you think that NOT will do what you want. But REV in PASM sounds much more like what you want.

I have no idea if there is a REV operator in Spin.

Or you can adapt this solution to Spin: http://stackoverflow.com/questions/746171/best-algorithm-for-bit-reversal-from-msb-lsb-to-lsb-msb-in-c

Ron Czapala

Is Bitwise Reverse '><' what you need? Trying to make sense of the example in the manual... EDIT: I See

Leon

Looks like bit-reversal, to me. I found this C function to do it:

http://www.geeksforgeeks.org/write-an-efficient-c-program-to-reverse-bits-of-a-number/

Duane Degn

Oldbitcollector (Jeff) wrote: »

Spin is just freak'n awesome..

Amen Brother!