How to make an ML routine part of a BASIC image

[wimoos]

If you have an ML routine that needs to be part of a BASIC program (in order to speed things up or some other reason), and the ML routine is relocatable, then you can do the following:

Determine the number of bytes that the routine needs.
Bump the pointer in 45:46 by that number of bytes.
Put the routine in that space.

SAVEing the program will include the ML routine.
Adding, modifying or deleting lines will not destroy your ML code, it stays there as long as you don't do a NEW.

Determine entry points of your routine relative to the contents of 45:46.

For an example check out the routine I developed for Jeff-20 at http://sleepingelephant.com/ipw-web/bul ... 5688#65688

The routine is relocatable and is 60 bytes long. The entry point is at the first location.

Load the routine first into e.g. the tapebuffer at 828.

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LOAD"PKW.PRG",8,1

Start with a clean slate

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NEW

Bump 45:46 by 60 bytes

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X=PEEK(45)+256*PEEK(46)
?X
(returns 1027 for example, remember it)

X=X+60:PRINT X AND 255; INT(X/256)
(results in 63 and 4 for example)

POKE 45,63:POKE 46,4:CLR

Copy your routine there

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FOR I=0 to 59:POKE 1027+I,PEEK(828+I):NEXT

During the initialisation of your program do the following:

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10 X=PEEK(45)+256*PEEK(46)-60
20 POKE1,XAND255:POKE2,X/256

Then, in your program you can use

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110 K$=USR(131)

Editing the BASIC program is without constraints, except when you do a NEW. Saveing the program will happily save the BASIC part plus the ML part. Loading again will put it all back in place.

Regards,

Wim

[Witzo]

I will remember this for future reference.