ref: 9fa7e376e33410e78fda13897bf8e0914f201ddf
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)
}