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--- language:langs:chp [2024/07/20 16:36] – [Advanced expression syntax] rajit
+++ language:langs:chp [2025/05/01 17:04] (current) – [Debugging during simulation] rajit
@@ Line 330: / Line 330: @@
 </code>
 where ''N'' is the number of channels in the ''I'' array. This approach ensures that index for the array ''I[]'' is always a constant.
+===== Debugging and other support functions for simulation =====
+When running CHP simulations, it is often helpful to print debugging output during CHP development. To support this, the CHP language includes the ''log()'' command.
+<code act>
+...
+chp {
+   ...
+   log ("Hello!");
+   ...
+}
+</code>
+The statement above will display ''Hello!'' on the [[tools:actsim|''actsim'']] output. The ''log'' statement can include variables and expressions as well:
+<code act>
+int x;
+...
+chp {
+    ...
+   log ("Hello, got: ", x+3, " and that's that.");
+   log ("%x This is hex: ", x+3);
+   log ("%b This is binary", x+3);
+   ...
+}
+</code>
+Booleans are displayed as integers, with ''0'' corresponding to false, ''1'' corresponding to true. Integers can also be displayed in hexadecimal, binary, or decimal (the default). The integer display mode can be changed with a prefix in a string, as shown in the example above.
+Other support functions of this type are:
+  * ''warn(string)'' : displays a warning
+  * ''assert(expr,string)'' : the first argument has to be an expression, and if it is non-zero then an assertion failed message is displayed.
+  * In the standard ''log'', a single line is displayed based on the items in the argument list. To split this into multiple ''log'' commands, use:
+     * ''log_st()'' : start a log message
+     * ''log_p(item,item,item...)'' : append to the output message, with the same syntax as the ''log()'' command.
+     * ''log_nl()'' : new line
 ====== The chp-txt sublanguage ======