18 lines
638 B
Org Mode
18 lines
638 B
Org Mode
#+title: representation of Scheme types
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the Scheme unitype is encoded as ~(ref eq)~ with immediates in ~(ref i31)~ and heap objects in ~$heap-object~:
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#+begin_src wat
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(type $heap-object (sub (struct (field $hash (mut i32)))))
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#+end_src
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* immediates
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all immediates are stored in ~(ref i31)~ and thus must fit in 31 bits. the most important immediate, the integer, is indicated by a null low bit.
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#+begin_example
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XXXX XXXX XXXX XXXX XXXX XXXX XXXX XX00
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|\ used by wasm's i31 rep
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zero indicates a 30-bit fixnum /
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in the upper bits
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#+end_example
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