Long shift register

[Joe Rocci]

I need to make a long shift register with 1000 taps or so. I'd like to be able to clock bits into it at a minimum 10 khz rate. I know how I'd do it in assembler, but I'd really like to implement it in PBP if feasable. Are there any tricks to streamline this process?

Joe

[Jerson]

How about inline assembly enclosed by ASM....ENDASM statements?

[Joe Rocci]

How about inline assembly enclosed by ASM....ENDASM statements?

That would defeat my goal. I wanted to see if I could do it all (or mostly) in PBP.

Thanks

Joe

[Chris Barron]

That would defeat my goal. I wanted to see if I could do it all (or mostly) in PBP.

Thanks

Joe

Are the picbasic commands 'shiftin' and 'shiftout' too slow for you ?

[Joe Rocci]

Are the picbasic commands 'shiftin' and 'shiftout' too slow for you ?

Chris

SHIFTOUT is an I/O function that toggles an output port with the bitwise contents of a data variable. SHIFTIN does the same thing in the other I/O direction.

What I want to do is set up a 'virtual' 1000 tap shift-register in the PIC's memory and be able to clock data through it. It's basically a digital delay line in memory, commonly used for digital signal processing applications. I need to clock it at a well-defined rate and also be able to read any of the 1000 tap points at any time.

It's quite straightforward in assembler, but I wanted to try to incorporate it into an existing PBP program using PBP's ">>" (shift right) and or "<<" (shift left) instructions instead of using assembler. I was hopng someone would tell me there are secret PBP system variables that capture the bits that are shifted OUT of an array variable so they can be shifted back IN to the next variable in the array. This way, a 63-word array could be set up as the 1000-bit shift-register, and bits could be clocked through the 1000 bits as though it were one long shift-register.

Joe

[Byte_Butcher]

well, I guess that you can only have bit arrays up to 256 elements, but I was thinking something like this..

bigarray 	var	  bit[256] 'Large array to hold data
newdata	var	  bit   'newest bit to be shifted in
index		var	  byte


for 0 to 255
    bigarray[index] = bigarray[index +1] 
    next index
    
bigarray[255] = newdata  'put the newest data bit into the array

Maybe with 4 big arrays you could shift through 1024 steps?
Or have I missed the point entirely...