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--- language:connections [2022/05/13 08:44]
rajit
+++ language:connections [2023/04/09 19:10]
rajit [Simple connections]
@@ Line 76: / Line 76: @@
 parameter variables as //immutable types//---they can only be
 defined once.
+===== Assertions =====
+Sometimes it is useful to be able to check that a parameter (or an expression of parameters) has a reasonable
+value. To express this, ACT supports explicit assertions. We use Hoare's syntax for assertions, so the assertion that
+''x'' must be ''8'' would be written
+<code act>
+{x=8};
+</code>
+If a more meaningful message is required, the following syntax is also supported:
+<code act>
+{x=8 : "This assertion failed"};
+</code>
+which also reports the message specified when the assertion failed.
+During circuit development/debugging, it may be helpful to assert that two signals are connected to each
+other or in fact disconnected from each other at a particular point during circuit construction. To assert that ''a'' is connected to ''b'', use:
+<code act>
+bool a;
+bool b;
+{ a !== b : "a and b are connected connected!" };  // this will pass
+a = b;
+{ a === b : "a and b are not connected!" }; // this will pass
+{ a !== b : "a and b are connected connected!" };  // this will fail
+</code>
+The operators ''==='' and ''!=='' are used to check that the two signals are connected or disconnected at the point the  assertion was encountered during circuit construction.
 ===== Array and subrange connections =====