Add blitv function

CHANGES

@@ -1,3 +1,6 @@
+1.6.0 (trunk):
+* Add `blitv` to copy over a list of buffers (from Thomas Leonard).
+
 1.5.0 (2014-11-24):
 * Make `camlp4` an optional build-time dependency (#35).
 * Remove `ounit` as a dependency in the `opam` file.

lib/cstruct.ml

@@ -231,6 +231,23 @@ let copyv ts =
     ) 0 ts in
   dst
 
+let blitv src dst =
+  let rec aux dst n = function
+    | [] -> n, []
+    | hd::tl ->
+        let avail = len dst in
+        let first = len hd in
+        if first <= avail then (
+          blit hd 0 dst 0 first;
+          aux (shift dst first) (n + first) tl
+        ) else (
+          blit hd 0 dst 0 avail;
+          let rest_hd = shift hd first in
+          (n + avail, rest_hd :: tl)
+        ) in
+  aux dst 0 src
+
+
 let to_string t =
   let sz = len t in
   let s = String.create sz in

lib/cstruct.mli

@@ -378,6 +378,13 @@ val copyv: t list -> string
 (** [copyv cstrs] is the string representation of the concatenation of
     all cstructs in [cstrs]. *)
 
+val blitv: t list -> t -> int * t list
+(** [blitv src dst] will copy the list of [src] buffers into [dst] and
+    return a tuple of the total number of bytes written and a list of
+    any uncopied buffers.  [blitv] will never raise an exception, since
+    it returns any uncopied bytes if the [dst] buffer is not big enough
+    to fit the full list of [src] buffers. *)
+
 (** {2 Iterations} *)
 
 type 'a iter = unit -> 'a option