Add optional signal filter predicate

embddr/vcd.scm

@@ -123,8 +123,9 @@
 ;;;
 ;;; Parse VCD header
 ;;; Returns values of timescale and association list (tag . (<signal> ...))
+;;; Predicate: (need-signal? <signal>)
 ;;;
-(define (read-header port)
+(define* (read-header port need-signal?)
   (let next-cmd ((timescale #f)
                  (scope '())
                  (tags+signals '()))
@@ -149,18 +150,20 @@
                            (else 'bits)))
                     (width (string->number (third cmd)))
                     (tag (fourth cmd))
-                    (vname (string-concatenate
-                            (insert-between
-                             (cddddr cmd) " "))))
+                    (name (string-concatenate
+                           (insert-between
+                            (cddddr cmd) " "))))
                 (next-cmd timescale scope
-                          (let ((tag+sig (assoc tag tags+signals))
-                                (sig (signal-new (reverse scope)
-                                                 vname type width '())))
-                            (if tag+sig
-                                (begin
-                                  (set-cdr! tag+sig (cons sig (cdr tag+sig)))
-                                  tags+signals)
-                                (cons (cons tag `(,sig)) tags+signals))))))
+                          (let ((sig (signal-new (reverse scope)
+                                                 name type width '())))
+                            (if (need-signal? sig)
+                                (let ((tag+sig (assoc tag tags+signals)))
+                                  (if tag+sig
+                                      (begin
+                                        (set-cdr! tag+sig (cons sig (cdr tag+sig)))
+                                        tags+signals)
+                                      (cons (cons tag `(,sig)) tags+signals)))
+                                tags+signals)))))
 
              ((string-ci= "$upscope" (first cmd))
               (next-cmd timescale (cdr scope) tags+signals))
@@ -258,7 +261,7 @@
 
                            ;; Update register values list
                            (let ((sigs (hash-table-ref/default tags+signals-ht tag #f)))
-                             (unless (null? sigs)
+                             (when sigs
                                (for-each
                                 (lambda (sig)
                                   (signal-add!
@@ -299,9 +302,9 @@
 ;;; Parse whole VCD
 ;;; Returns list of time stamps and list of lists (<signal> valuse ...)
 ;;;
-(define (vcd-parse port)
+(define* (vcd-parse port #:optional (need-signal? (lambda (s) #t)))
   (call-with-values
-      (lambda () (read-header port))
+      (lambda () (read-header port need-signal?))
     (cut read-data port <...>)))
 
 ;;;