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: