ref: d60e706a5f499863320b9359519438c62a4df303
dir: /lib/std/varargs.myr/
use "types.use" use "introspect.use" use "sleq.use" use "die.use" pkg std = type valist const vastart : (args : ...# -> valist) const vatype : (ap : valist# -> byte[:]) const vabytes : (ap : valist# -> byte[:]) const vaenter : (ap : valist# -> valist) generic vanext : (ap : valist# -> @a) ;; type valist = struct args : byte# tc : typecursor ;; /* * 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 tc, a, ip /* pull out the args. These are on the stacks like so: [ required ] [ args ] ---variadic--- [ typeinfo ] --> type description ------------ [ variadic ] [ args ] [ here ] &args points to the typeinfo, &args + sizeof(void#) points to the rest argument. */ tc = typeenc(args) ip = (args castto(intptr)) + sizeof(byte#) a = ip castto(byte#) -> [.args = a, .tc = tc] } const vaenter = {ap match typedesc(vatype(ap)) | `Tyslice enc: -> [.args=sliceptr(ap.args), .tc=[.nelt=slicelen(ap.args), .rem=enc, .isiter=false]] | `Tytuple tc: -> [.args=ap.args, .tc=tc] | `Tystruct tc: -> [.args=ap.args, .tc=tc] | `Tyunion tc: -> [.args=addp(ap.args, 4), .tc=tc] | `Tyarray (sz, enc): -> [.args=ap.args, .tc=[.nelt=sz, .rem=enc, .isiter=false]] | `Tyname (name, enc): -> [.args=ap.args, .tc=typeenccursor(enc)] | _: std.die("unable to enter type") ;; } const vatype = {ap -> tcpeek(&ap.tc) } const vabytes = {ap var sl var ti, align, sz var p ti = typeinfo(tcpeek(&ap.tc)) /* apply the alignment to the arg pointer */ align = ti.align castto(intptr) p = ap.args castto(intptr) p = (p + align - 1) & ~(align - 1) ap.args = p castto(byte#) sl = ap.args[:ti.size] tcnext(&ap.tc) sz = ti.size castto(intptr) ap.args = ((p castto(intptr)) + sz) castto(byte#) -> sl } generic vanext = {ap -> @a var ti var align var p ti = typeinfo(tcpeek(&ap.tc)) /* apply the alignment to the arg pointer */ align = ti.align castto(intptr) p = ap.args castto(intptr) p = (p + align - 1) & ~(align - 1) /* TODO: check for type mismatch */ tcnext(&ap.tc) /* only move on after we read through the value */ ap.args = ((p castto(intptr)) + sizeof(@a)) castto(byte#) -> (p castto(@a#))# } const addp = {p, k -> (p castto(intptr)) + k castto(byte#) } const sliceptr = {p -> (p castto(byte##))# } const slicelen = {p p = addp(p, sizeof(intptr)) -> (p castto(size#))# }