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jaystainbrook
PostPosted: Tue Feb 04, 2020 11:56 pm 
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Is it possible to compile a new NEXT in the dictionary that will replace the built in word in Fig Forth? I wrote a replacement to test and it will call my NEXT only once after I load the block it's in but reverts to the original NEXT afterwards.
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GARTHWILSON
PostPosted: Wed Feb 05, 2020 12:11 am 
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One way to replace it is to have it in RAM so you overwrite the first three bytes to hold a jump instruction to your new NEXT routine, since all primitives are already assembled with JMP NEXT at the end. I do a related thing in my '816 Forth in that it's an indirect jump, and the intermediate address holds the address of the NEXT you want to execute. The reason for this is to jump immediately into Forth interrupt service when appropriate (and that version of NEXT is actually shorter and faster than the standard NEXT!), or you could have other versions of NEXT for things like instruction trace, single-stepping, etc., although I have not implemented the latter two. Most of the time, this indirect variable will just hold the address of the normal NEXT to jump to.

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barrym95838
PostPosted: Wed Feb 05, 2020 1:46 am 
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I think that you would have to replace every JMP NEXT (about 18 of them) in the source with JMP MYNEXT ... or just poke MYNEXT into the space originally occupied by NEXT.

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