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(*
* Copyright (C) 2006-2009 Citrix Systems Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; version 2.1 only. with the special
* exception on linking described in file LICENSE.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*)
type t = {
sz: int;
data: string;
mutable prod: int;
mutable cons: int;
mutable pwrap: bool;
}
exception Data_limit
exception Full
let make sz = { sz = sz; data = String.create sz; prod = 0; cons = 0; pwrap = false }
let to_consume ring =
if ring.pwrap then
ring.sz - (ring.cons - ring.prod)
else
ring.prod - ring.cons
let to_fill ring =
if ring.pwrap then
ring.cons - ring.prod
else
ring.cons + (ring.sz - ring.prod)
let is_full ring = ring.pwrap && ring.prod = ring.cons
let is_empty ring = not ring.pwrap && ring.prod = ring.cons
let adv_cons ring i =
ring.cons <- ring.cons + i;
if ring.cons >= ring.sz then (
ring.cons <- ring.cons - ring.sz;
ring.pwrap <- false;
)
let adv_prod ring i =
ring.prod <- ring.prod + i;
if ring.prod >= ring.sz then (
ring.prod <- ring.prod - ring.sz;
ring.pwrap <- true;
)
let consume ring sz =
let max = to_consume ring in
let sz =
if sz > 0 then
if sz > max then max else sz
else
if max + sz > 0 then max + sz else 0
in
let out = String.create sz in
if ring.pwrap then (
let left_end = ring.sz - ring.cons in
if sz > left_end then (
String.blit ring.data ring.cons out 0 left_end;
String.blit ring.data 0 out left_end (sz - left_end);
) else
String.blit ring.data ring.cons out 0 sz;
) else
String.blit ring.data ring.cons out 0 sz;
adv_cons ring sz;
out
let consume_all ring = consume ring (max_int)
let skip ring n =
let max = to_consume ring in
let n = if n > max then max else n in
adv_cons ring n
let feed_data ring data =
let len = String.length data in
let max = to_fill ring in
if len > max then
raise Data_limit;
if ring.prod + len > ring.sz then (
let firstblitsz = ring.sz - ring.prod in
String.blit data 0 ring.data ring.prod firstblitsz;
String.blit data firstblitsz ring.data 0 (len - firstblitsz);
) else
String.blit data 0 ring.data ring.prod len;
adv_prod ring len;
()
(* read and search directly to the qring.
* since we have give a continuous buffer, we limit our read length to the
* maximum continous length instead of the full length of the qring left.
* after the read, piggyback into the new data.
*)
let read_search ring fread fsearch len =
let prod = ring.prod in
let maxlen =
if ring.pwrap
then ring.cons - ring.prod
else ring.sz - ring.prod
in
if maxlen = 0 then
raise Full;
let len = if maxlen < len then maxlen else len in
let n = fread ring.data prod len in
if n > 0 then (
adv_prod ring n;
fsearch ring.data prod n
);
n
let search ring c =
let search_from_to f t =
let found = ref false in
let i = ref f in
while not !found && !i < t
do
if ring.data.[!i] = c then
found := true
else
incr i
done;
if not !found then
raise Not_found;
!i - f
in
if is_empty ring then
raise Not_found;
if ring.pwrap then (
try search_from_to ring.cons ring.sz
with Not_found -> search_from_to 0 ring.prod
) else
search_from_to ring.cons ring.prod
|
