ref: ae222f2157fa57dd27ff23bcb13c78adc08627b2
dir: /libstd/varargs.myr/
use "types.use" pkg std = type valist const vastart : (args : ...# -> valist) generic vanext : (ap : valist -> (@a, valist)) ;; type valist = byte# /* * a valist is really just a pointer to the varargs. * we assume that these sit on the stack nicely, * and don't need special handling to get to. * * This will be a problem when we switch to a * register based convention. We might want to * force varargs onto the stack regardless. */ const vastart = {args var ap, dump : byte# (dump, ap) = vanext(args castto(valist)) -> ap } generic vanext = {ap -> (@a, valist) var v : @a var align var p /* Assumptions about the ABI: * all types smaller than a word are * aligned to their own size. Larger * types are aligned to word size. */ if sizeof(@a) > 8 align = 8 else align = sizeof(@a) ;; /* apply the alignment to the arg pointer */ p = ap castto(intptr) p = (p + align - 1) & ~(align - 1) ap = p castto(valist) v = (ap castto(@a#))# /* only move on after we read through the value */ ap = ((p castto(intptr)) + sizeof(@a)) castto(valist) -> (v, ap) }