Differences

This shows you the differences between two versions of the page.

--- mozaic_tips_and_tricks [2020/03/01 22:06] – Fixed NOTOC _ki
+++ mozaic_tips_and_tricks [2020/07/12 21:46] – Added: Using Inc and Dec in Expressions _ki
@@ Line 14: / Line 14: @@
   * [[#Use a Knob to toggle 16 Pads View to HELP View]]
   * [[#Knob double-tap Support]]
+  * [[#Using Inc and Dec in Expressions]]
   * [[#Calculate Standard Chords from a Root Note]]
@@ Line 224: / Line 225: @@
-If a knob is only used to toggle between two states like a switch, the code for double-tap detection would look like:
+If a knob is only used to toggle between two states like a switch (like the variable //isOn// in the example), the code for double-tap detection would look like:
 <code>
+@OnKnobChange
+  _knob = LastKnob
+  _val  = GetKnobValue _knob
+  if _knob = TOGGLE_KNOB
+    if _val = 64
+      isOn = not isOn
+      SetKnobValue TOGGLE_KNOB,48 + 32*isOn
+    else
+      isOn = _val > 64
+    endif
+    if isOn
+      LabelKnob TOGGLE_KNOB,  {ON}
+    else
+      LabelKnob TOGGLE_KNOB,  {OFF}
+    endif
+  endif
+@End
 @OnLoad
   ShowLayout 2
@@ Line 246: / Line 267: @@
   else
     LabelKnob TOGGLE_KNOB,  {OFF}
-  endif
-@End
-@OnKnobChange
-  _knob = LastKnob
-  _val  = GetKnobValue _knob
-  if _knob = TOGGLE_KNOB
-    if _val = 64
-      isOn = not isOn
-      SetKnobValue TOGGLE_KNOB,48 + 32*isOn
-    else
-      isOn = _val > 64
-    endif
-    if isOn
-      LabelKnob TOGGLE_KNOB,  {ON}
-    else
-      LabelKnob TOGGLE_KNOB,  {OFF}
-    endif
   endif
 @End
@@ Line 275: / Line 276: @@
     * //isOn = _val > 64// assigns either 0 or 1 to //isOn// depending on _val
+\\
+===== Using Inc and Dec in Expressions =====
+<html><p align = "right"><small><i>From -ki</i></small></p></html>
+TheOriginalPaulB discovered that Inc and Dec are working as functions. Both Inc and Dec are ‚pre-increment‘ operations like ++var  in C, as the function returns the already incremented value. This allows for several interesting language constructs:
+In case of a ring buffer index, one could use
+<code>
+  index = (Inc index) % 64
+</code>
+instead of the longer construct
+<code>
+  Inc index
+  index = index % 64
+</code>
+\\
+Sometimes this trick is also applicable in array initialization, but one has to compensate for the pre-increment.
+<code>
+  idx = -1
+  for i = 10 to 19
+    array[Inc idx] = 2*i
+  endfor
+</code>
+The example fills array[0] to array[9] with the values 20 to 38. To compensate for pre-increment, idx needs to start at -1 since it will be incremented to zero on first usage
+\\
+It is also possible to construct a post-increment operation by using the inc in the expression itself, but discarding it using multiplication with 0:
+<code>
+  idx = 0
+  for i = 10 to 19
+    array[idx] = 2*i  + 0*(Inc idx)
+  endfor
+</code>
 \\