Data commit

Task/Knuth-shuffle/Vedit-macro-language/knuth-shuffle.vedit

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+// Test main
+#90 = Time_Tick                   // seed for random number generator
+#99 = 20                          // number of items in the array
+
+IT("Before:") IN
+for (#100 = 0; #100 < #99; #100++) {
+    #@100 = #100
+    Num_Ins(#@100, LEFT+NOCR) IT(" ")
+}
+IN
+
+Call("SHUFFLE_NUMBERS")
+
+IT("After:") IN
+for (#100 = 0; #100 < #99; #100++) {
+    Num_Ins(#@100, LEFT+NOCR) IT(" ")
+}
+IN
+Return
+
+//--------------------------------------------------------------
+// Shuffle numeric registers #0 to #nn
+//  #99 = number of registers to shuffle (nn-1)
+//
+:SHUFFLE_NUMBERS:
+for (#91 = #99-1; #91 > 0; #91--) {
+    Call("RANDOM")
+    #101 = Return_Value
+    #102 = #@101; #@101 = #@91; #@91 = #102
+}
+Return
+
+//--------------------------------------------------------------
+// Generate random numbers in range 0 <= Return_Value < #91
+//  #90 = Seed    (0 to 0x7fffffff)
+//  #91 = Scaling (0 to 0x10000)
+//
+:RANDOM:
+#92 = 0x7fffffff / 48271
+#93 = 0x7fffffff % 48271
+#90 = (48271 * (#90 % #92) - #93 * (#90 / #92)) & 0x7fffffff
+Return ((#90 & 0xffff) * #91 / 0x10000)