A86: Re: FIND_PIXEL on the 85


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A86: Re: FIND_PIXEL on the 85




from zsfnlib.txt:

FIND_PIXEL

Call method: ROM_CALL(FIND_PIXEL)
Input:       B = X coordinate
             C = Y coordinate
Returns:     HL = offset in video buffer
             A = Value of bit to change

Description: This function returns the offset and bit-value of a given
pixel on the graphics screen. It is useful if you want to set, reset or
read a single pixel. If you want to update a larger area of the screen, you
should use direct memory access. Check this page for example of routines
that use this function.
Traps: HL and A are (naturally) destroyed. This function must be executed
when memory page is set to 4. To do this, use the following code:

   ld   a,4
   out  (5),a

Example:

   ld   b,10
   ld   c,50                ;Put pixel at (10,50)
   ROM_CALL(FIND_PIXEL)
   or   (hl)
   ld   (hl),a

----- Original Message ----- 
From: <McBorder@aol.com>
To: <assembly-86@lists.ticalc.org>
Sent: Thursday, May 27, 1999 9:05 PM
Subject: A86: FIND_PIXEL on the 85


> 
> does anyone know what FIND_PIXEL takes as input and what is its output
> i  think it takes b,c but are b and c or d and e saved???? 
> 
> 



References: