forth: String word set COMPARE/SEARCH/SLITERAL (+9)

lib/forth/runtime.sx

@@ -381,6 +381,46 @@
             (dict-set! state "hold" (cons ch (get state "hold")))
             (forth-double-push-u state rest)))))))
 
+(define
+  forth-compare-bytes-loop
+  (fn
+    (state a1 u1 a2 u2 i)
+    (cond
+      ((and (= i u1) (= i u2)) 0)
+      ((= i u1) -1)
+      ((= i u2) 1)
+      (else
+        (let
+          ((b1 (forth-mem-read state (+ a1 i)))
+            (b2 (forth-mem-read state (+ a2 i))))
+          (cond
+            ((< b1 b2) -1)
+            ((> b1 b2) 1)
+            (else (forth-compare-bytes-loop state a1 u1 a2 u2 (+ i 1)))))))))
+
+(define
+  forth-match-at
+  (fn
+    (state a1 start a2 u2 j)
+    (cond
+      ((= j u2) true)
+      ((not
+        (=
+          (forth-mem-read state (+ a1 (+ start j)))
+          (forth-mem-read state (+ a2 j))))
+        false)
+      (else (forth-match-at state a1 start a2 u2 (+ j 1))))))
+
+(define
+  forth-search-bytes
+  (fn
+    (state a1 u1 a2 u2 i)
+    (cond
+      ((= u2 0) 0)
+      ((> (+ i u2) u1) -1)
+      ((forth-match-at state a1 i a2 u2 0) i)
+      (else (forth-search-bytes state a1 u1 a2 u2 (+ i 1))))))
+
 (define
   forth-pic-S-loop
   (fn