Add Lispusers BACKGROUND-YIELD to call new subr (#488)

* Add Lispusers BACKGROUND-YIELD to call new subr

* Make BACKGROUND-YIELD a variable

lispusers/BACKGROUND-YIELD

@@ -0,0 +1,50 @@
+(DEFINE-FILE-INFO PACKAGE "INTERLISP" READTABLE "INTERLISP" BASE 10)
+
(FILECREATED "20-Sep-2021 11:37:28" {DSK}<home>larry>medley>lispusers>BACKGROUND-YIELD.;3
 1644   
+
+      changes to%:  (FNS BACKGROUND-YIELD)
+                    (VARS BACKGROUND-YIELDCOMS)
+
+      previous date%: "19-Sep-2021 13:37:10" {DSK}<home>larry>medley>lispusers>BACKGROUND-YIELD.;1)
+
+
+(PRETTYCOMPRINT BACKGROUND-YIELDCOMS)
+
+(RPAQQ BACKGROUND-YIELDCOMS
 (
+                                 (* ;; 
+
                               " Add a call to BACKGROUNDFNS to yield when not otherwise busy")

+
+                                 (FNS BACKGROUND-YIELD INIT-YIELD)
+                                 (DECLARE%: DONTEVAL@LOAD DOCOPY (P (INIT-YIELD T)))
+                                 (VARS BACKGROUND-YIELD)))
+
+
+
+(* ;; " Add a call to BACKGROUNDFNS to yield when not otherwise busy")

+
+(DEFINEQ
+
+(BACKGROUND-YIELD

+  [LAMBDA NIL
                                          (* ; "Edited 20-Sep-2021 11:37 by larry")

+    (IF
 (FIXP BACKGROUND-YIELD)
+        THEN
 (SUBRCALL YIELD BACKGROUND-YIELD)
+              (SUBRCALL CAUSE-INTERRUPT])
+
+(INIT-YIELD

+  [LAMBDA (ONP)
                                        (* ; "Edited 19-Sep-2021 13:32 by larry")

+    (SETQ BACKGROUNDFNS (REMOVE 'BACKGROUND-YIELD BACKGROUNDFNS))
+    (if
 [AND ONP (CCODEP (GETD 'BACKGROUND-YIELD]
+        then
 
+
+              (* ;; " add to end")

+
+              (SETQ BACKGROUNDFNS (APPEND BACKGROUNDFNS '(BACKGROUND-YIELD
])
+)
+(DECLARE%: DONTEVAL@LOAD DOCOPY 
+
+(INIT-YIELD
 T)
+)
+
+(RPAQQ BACKGROUND-YIELD
 8333330)
+(DECLARE%: DONTCOPY
+  (FILEMAP (NIL (879 1528 (BACKGROUND-YIELD 889 . 1144) (INIT-YIELD 1146 . 1526)))))
+STOP