Haskell FFI - How to handle C functions that accept or return structs instead of pointers to structs? -


of course answer somehow pass/take contiguous block of memory, question more how that. still avoid issue writing wrapper functions on c side, that's not of permament solution.

the ffi doesn't support arbitrary pass value haskell storable types.

you may pass values of type (and of these pointers):

int#, word#, char#, float#, double#, addr#, stableptr# a, mutablebytearray#, foreignobj#, , bytearray#.

so, pass structure must wrap call via c wrapper; takes pointer , passes value c function wish call.

a recent ghc extension allows "primop" imports -- bypass ffi mechanism , support arbitrary calling conventions , passing structures via unboxed tuples. e.g.

foreign import prim "itchv41_run"   parseitchv41# :: addr# -> word#                 -> (# int#, word#, word#, word#, word#, word# #)

you can use these tricky low level stuff this.


Comments

Post a Comment

Popular posts from this blog

jquery - Invalid Assignment Left-Hand Side -

i trying assign class tag via jquery, resulting in error through firebug says "invalid assignment left-hand side" on fourth line below. <cfoutput> $('.pngfix a').each(function(index) { var hreflink = $(this).attr("href"); if (hreflink.tolowercase() = '../audio.cfm') { $(this).addclass('audioimg'); } }); </cfoutput> looking around online, looks syntax problem, don't seem see it... any tips? thanks if (hreflink.tolowercase() = '../audio.cfm') that attempts assign value, rather check equality. change = operator == .
Read more

java - Play! framework 2.0: How to display multiple image? -

i need display gallery of photos. here template: @(photos: list[photo]) @title = { <bold>gallery</bold> } @main(title,"photo"){ <ul class="thumbnails"> @for(photo <- photos) { <li class="span3"> <a href="#" class="thumbnail"> <img src="@photo.path" alt=""> </a> </li> } </ul> } and here controller method: public static result getphotos() { return ok(views.html.photo.gallery.render(photo.get())); } and here photo bean : @entity public class photo extends model { @id public long id; @required public string label; public string path; public photo(string path, string label) { this.path = path; this.label = label; } private static finder<long, photo> find = new finder<long, photo>( long.class, photo.class); public static list<phot...
Read more

gmail - Is there any documentation for read-only access to the Google Contacts API? -

i want read-only access user's google contacts. there stackoverflow member wanted this, , received following answer : yes, there is, use https://www.googleapis.com/auth/contacts.readonly scope , "view contacts". this exchange reference read-only access google contacts can find using google. simply using access token obtained attempt read usual google contacts api (i.e. https://www.google.com/m8/feeds ) fails insufficient permissions. similarly, using google contacts api on new target fails 404 errors (for example https://www.googleapis.com/auth/contacts.readonly/default/full ). is there documentation anywhere on how use api, or permissible way access google contacts api full read-write access?
Read more