Data commit

Task/Gray-code/NOWUT/gray-code.nowut

@@ -0,0 +1,64 @@
+; link with PIOxxx.OBJ
+
+        sectiondata
+
+output:         db " : "
+inbinary:       db "00000 => "
+graybinary:     db "00000 => "
+outbinary:      db "00000"
+                db 13,10,0        ; carriage return and null terminator
+
+        sectioncode
+
+start!
+        gosub initplatform
+
+        beginfunc
+        localvar i.d,g.d,b.d
+
+        i=0
+        whileless i,32
+        callex g,gray_encode,i
+        callex b,gray_decode,g
+
+        callex ,bin2string,i,inbinary,5              ; 5 = number of binary digits
+        callex ,bin2string,g,graybinary,5
+        callex ,bin2string,b,outbinary,5
+
+        callex ,printhex8,i                  ; display hex value
+                                             ; because there is no PIO routine for decimals...
+        callex ,printnt,output.a
+
+        i=_+1
+        wend
+
+        endfunc
+        end
+
+gray_encode:
+        beginfunc n.d
+        n=_ xor (n shr 1)
+        endfunc n
+        returnex 4                           ; clean off 1 parameter from the stack
+
+gray_decode:
+        beginfunc n.d
+        localvar p.d
+        p=n
+        whilegreater n,1
+        n=_ shr 1 > p=_ xor n
+        wend
+        endfunc p
+        returnex 4                           ; clean off 1 parameter from the stack
+
+bin2string:
+        beginfunc digits.d,straddr.d,value.d
+
+        whilegreater digits,0
+        digits=_-1
+        [straddr].b=value shr digits and 1+$30        ; write an ASCII '0' or '1'
+        straddr=_+1                                   ; increment the pointer
+        wend
+
+        endfunc
+        returnex $0C                         ; clean off 3 parameters from the stack