Groups > comp.sys.apple2.programmer > #4742

Efficient print of binary value

From	Jan Poulsen <jpo@tiggr.dk>
Newsgroups	comp.sys.apple2.programmer
Subject	Efficient print of binary value
Date	2018-09-05 15:07 +0200
Organization	A noiseless patient Spider
Message-ID	<pmokev$c9j$1@dont-email.me> (permalink)

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Hi all,

As part of debugging and trying to understand how some code is working, 
I have a need of printing bytes in binary format.  I've googled around 
to see if anyone had already come up with something, but there doesn't 
seem to have been a need for printing binary values.

So, I've written the code below, but hope someone has a smarter/faster 
way of doing it.

The value to be printed in binary should be in the accumulator before 
calling the routine.

PRHEX	.EQ $FDE3
RESTOR	.EQ $FF3F
SAVE	.EQ $FF4A

PRBIN
	JSR SAVE	; save registers and processor status
	LDY #8		; 8 bits to process
.1	ASL		; drop high bit in carry and 0 in low bit
	TAX		; save A for next iteration
	ROL		; move carry to low bit
	AND #1		; mask out all but the low bit
	JSR PRHEX	; print lower nibble of A (high bit)
	TXA		; restore A
	DEY		; decrease counter
	BNE .1		; more bits to print?
	JMP RESTOR	; restore regs & status

As this is used for debugging I'm saving the state of the machine before 
doing anything else, and restoring it upon exit.  I could probably get 
away with the following code to save a few cycles instead of calling 
SAVE and RESTORE as I am not using X and Y in the code I am trying to 
understand.

PHP
PHA
...
PLA
PLP

Any ideas for more efficient code or code that only uses A so I don't 
have to save X and Y for other types of debugging, will be much appreciated.

--
Jan Poulsen

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Thread

Efficient print of binary value Jan Poulsen <jpo@tiggr.dk> - 2018-09-05 15:07 +0200
  Re: Efficient print of binary value Marco Verpelli <mverpelli@libero.it> - 2018-09-05 07:23 -0700
    Re: Efficient print of binary value Jan Poulsen <jpo@tiggr.dk> - 2018-09-05 17:05 +0200
      Re: Efficient print of binary value Michael J. Mahon <mjmahon@aol.com> - 2018-09-05 11:01 -0500
        Re: Efficient print of binary value qkumba <peter.ferrie@gmail.com> - 2018-09-05 11:13 -0700
          Re: Efficient print of binary value Michael J. Mahon <mjmahon@aol.com> - 2018-09-05 14:18 -0500
          Re: Efficient print of binary value Marco Verpelli <mverpelli@libero.it> - 2018-09-05 12:32 -0700
            Re: Efficient print of binary value Michael J. Mahon <mjmahon@aol.com> - 2018-09-05 22:21 -0500
          Re: Efficient print of binary value awanderin <awanderin@gmail.com> - 2018-09-05 23:53 -0600
            Re: Efficient print of binary value Jan Poulsen <jpo@tiggr.dk> - 2018-09-06 13:04 +0200
            Re: Efficient print of binary value Michael Barry <barrym95838@yahoo.com> - 2018-09-06 23:54 -0700
              Re: Efficient print of binary value awanderin <awanderin@gmail.com> - 2018-09-07 09:01 -0600

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