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performance [2019/08/01 12:26] – [Tip #6: use ON for branching] neilsperformance [2019/08/05 11:47] – [Tip #8 REPEAT ... UNTIL is faster than FOR ... NEXT] neils
Line 82: Line 82:
   on x! goto false_case, true_case   on x! goto false_case, true_case
  
-==== Tip #7 REPEAT ... UNTIL is faster than FOR ... NEXT ====+==== Tip #8 REPEAT ... UNTIL is faster than FOR ... NEXT ====
  
 You can gain some speed boost using ''REPEAT ... UNTIL'' instead of  ''FOR ... NEXT'': You can gain some speed boost using ''REPEAT ... UNTIL'' instead of  ''FOR ... NEXT'':
Line 97: Line 97:
     inc i!     inc i!
   until i! = 100   until i! = 100
 +  
 +==== Tip #9: Know the optimizer ====
 +
 +**XC=BASIC** features a built-in optimizer that replaces commonly used program sequences with faster opcode sequences. To make good use of the optimizer, bear in mind the following program structures that can be optimized:
 +
 +  * Value assignment of bytes and integers
 +  * Addition of bytes and integers
 +  * Subtraction of bytes and integers
 +  * Comparison of bytes, e. g. ''IF x! > 5 THEN ...''
 +  * ''IF'', ''WHILE'' and ''UNTIL'' statements with byte type comparison as condition, e .g ''WHILE x! <= 255''
 +  * Array access of byte type arrays with byte type index
 +  * Bitwise operators on bytes
 +  * POKE and PEEK (they're the fastest when using constant addresses)
 +
 +The following are not optimized at all:
 +
 +  * Operations on floating point types
 +  * I/O commands like ''PRINT'', etc.
 +  * Convenience commands like ''TEXTAT''