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ed2b91411a
I'm planning on going back to 8-bit branching. 16-bit br cells incur a non-negligible penalty and, while at first 64 words (128 bytes forward or backward) seemed a bit limiting, I now don't see why one would ever construct such a big branch. It would be un-forthy. Also, I looked at using BC instead of IY to hold IP and the transition would be a lot easier with 8-bit branching. In this commit, all I do is add overflow checks in IF. The mechanic below doesn't change. I'll give myself some time to think it over so that I avoid yet another back and forth.
14 lines
325 B
Plaintext
14 lines
325 B
Plaintext
: IF ( -- a | a: br cell addr )
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COMPILE (?br) H@ 2 ALLOT ( br cell allot )
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; IMMEDIATE
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: THEN ( a -- | a: br cell addr )
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DUP H@ -^ _bchk SWAP ( a-H a ) !
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; IMMEDIATE
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: ELSE ( a1 -- a2 | a1: IF cell a2: ELSE cell )
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COMPILE (br)
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2 ALLOT
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[COMPILE] THEN
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H@ 2- ( push a. -2 for allot offset )
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; IMMEDIATE
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