\ Copyright 2021 Bradley D. Nelson 
\ 
\ Licensed under the Apache License, Version 2.0 (the "License"); 
\ you may not use this file except in compliance with the License. 
\ You may obtain a copy of the License at 
\ 
\     http://www.apache.org/licenses/LICENSE-2.0 
\ 
\ Unless required by applicable law or agreed to in writing, software 
\ distributed under the License is distributed on an "AS IS" BASIS, 
\ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
\ See the License for the specific language governing permissions and 
\ limitations under the License. 
 
( Byte Stream / Ring Buffer ) 
 
vocabulary streams   streams definitions 
 
: stream ( n "name" ) create 1+ dup , 0 , 0 , allot align ; 
: >write ( st -- wr ) cell+ ;   : >read ( st -- rd ) 2 cells + ; 
: >offset ( n st -- a ) 3 cells + + ; 
: stream# ( sz -- n ) >r r@ >write @ r@ >read @ - r> @ mod ; 
: full? ( st -- f ) dup stream# swap @ 1- = ; 
: empty? ( st -- f ) stream# 0= ; 
: wait-write ( st -- ) begin dup full? while pause repeat drop ; 
: wait-read ( st -- ) begin dup empty? while pause repeat drop ; 
: ch>stream ( ch st -- ) 
   dup wait-write 
   >r r@ >write @ r@ >offset c! 
   r@ >write @ 1+ r@ @ mod r> >write ! ; 
: stream>ch ( st -- ch ) 
   dup wait-read 
   >r r@ >read @ r@ >offset c@ 
   r@ >read @ 1+ r@ @ mod r> >read ! ; 
: >stream ( a n st -- ) 
   swap for aft over c@ over ch>stream swap 1+ swap then next 2drop ; 
: stream> ( a n st -- ) 
   begin over 1 > over empty? 0= and while 
   dup stream>ch >r rot dup r> swap c! 1+ rot 1- rot repeat 2drop 0 swap c! ; 
 
forth definitions 
 

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