Mercurial > hg > index.cgi
view docs/internals.txt @ 264:346966cffeef
Clean up various warnings when building under -Wall
Add some gimmicks to prevent fread() and fwrite() warnings about ignoring
the return value. Yes, this is probably not a good thing to do, but doing
something with a non-success return value is going to involve crashing out
or something anyway.
Also fix several warnings about variables used while possibly uninitialized.
The code flow shows that this cannot be the case but initializing them to a
plausible value at declaration time costs pretty much nothing and it makes
gcc happy.
Also caught a use of | instead of || which probably would have caused a
certain check for duplicate declarations in __os9 sections to behave oddly.
| author | William Astle <lost@l-w.ca> |
|---|---|
| date | Wed, 06 Feb 2013 21:43:10 -0700 |
| 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.