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Add integer shifts and fix code template errors for mul/div/mod
One needs to remove stuff from the stack after putting it there. Actually do
that in the code output for multiplication, division, and modulus.
Add integer shifting code output which is optimized for constant shift
counts but calls a routine for non-constant shift counts. Shifting by a
negative amount is a no-op. Shifting by more than the size of an integer
results in 0 (for left shifts) or -1 (for right shifts). Both negative shift
counts and shift counts larger than the base type are undefined in the C
standard so this behaviour is allowed.
| author | William Astle <lost@l-w.ca> |
|---|---|
| date | Sat, 26 Oct 2019 22:01:55 -0600 |
| parents | 2c24602be78f |
| children |
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LWASM Internals =============== LWASM is a table-driven assembler that notionally uses two passes. However, it implements its assembly in several passes as follows. Pass 1 ------ This pass reads the entire source code and parses each line into an internal representation. Macros, file inclusions, and conditional assembly instructions are resolved at this point as well. Instructions with known sizes will have their sizes resolved at this point. Pass 2 ------ Check all exported symbols for validity and set them as imports if the assembler state says so. Also resolve all symbol references in all expressions to be direct references either to the symbol table or to the import list. Pass 3 ------ This pass resolves all instruction sizes that can be resolved without forcing any instruction sizes. This pass will run repeatedly until no no new resolution occurs. Pass 4 ------ Work through all un-resolved instructions and force sizes. After each size is forced, try re-resolving all other instructions. This is done starting at the beginning of the source and working forward. If any instruction does not resolve when forced, an error will be thrown. Pass 5 ------ Constantize all line addresses and throw errors if any cannot be. This pass will repeat until no further lines addresses are reduced to constants at which time all lines will be checked for constant-ness. Pass 6 ------ Finalize all expressions related to instructions. Carp about any that cannot be reduced to a usable form. That means, for the non-object target all expressions must resolve to a constant. For the object form, all expressions must resolve to symbol references and constants. Those symbol references may be internal or external. Pass 7 ------ Emit object code for each line for later output.