Re: LuaJIT2 FFI Help
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- Subject: Re: LuaJIT2 FFI Help
- From: Mike Pall <mikelu-1104@...>
- Date: 2011年4月18日 02:17:25 +0200
Gerry Weaver wrote:
> I guess I'm basically having issues figuring out how to handle
> function args that set a value, or more specifically, the
> <type>** case. I would really appreciate a nudge in the right
> direction on this.
These are typical C 'outargs'. In C you'd pass the address of a
local variable that receives the result. How to handle this with
the LuaJIT FFI is shown here:
http://luajit.org/ext_ffi_tutorial.html#idioms
Also, check out the zlib tutorial at
http://luajit.org/ext_ffi_tutorial.html#zlib
and pay particular attention to the 'buflen' variable.
For your example that would be (untested):
local mylib = ffi.load("my_lib")
local ctxp = ffi.new("my_ctx_t *[1]")
if mylib.my_init(ctxp) then
local ctx = ctxp[0]
local strp = ffi.new("char *[1]")
if mylib.my_get_string(ctx, strp) then
local str = strp[0]
print("Result:", ffi.tostring(str))
else
error("...")
end
mylib.my_term(ctx)
else
error("...")
end
--Mike