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Title: Taming Testbench Messaging and Error Reporting with OSVVM's Logs and Alerts

Description: Printing and error reporting in VHDL are tedious, yet necessary testbench tasks. Fortunately, Open Source VHDL Verification Methodology (OSVVM) provides library utilities to simplify these tasks. This presentation covers the details of OSVVMs transcript utility in TranscrptPkg as well as OSVVM's logs, alerts, and affirmations in AlertLogPkg. Testbench printing consists of messages from different entities. To collect the output from different sources into a single file will generally result in the usage of OUTPUT and intermingling of test results with simulator messages. OSVVM transcripts allow the collection of all test outputs into either OUTPUT or a named file. Printing in VHDL involves TEXTIO which requires multiple calls to write followed by a call to writeline. OSVVM focuses on printing type string and uses the VHDL-2008 to_string functions to handle any necessary conversions. Hence, simple printing is a single call to print. Going further will test the need to filter messages. Only print a particular message during the debug. Print another message when testing is complete and we need printing to document what tests were run and passed. OSVVM is capable of handling this through its logging utility. Error handling in tests can be complicated and error prone. Error handling involves printing (the easy part) and error counting. Unfortunately, the error counting requires a separate signal for each process that can detect an error. When the test completes, we sum up all of the error sources and print a pass / fail report. OSVVM handles error counting and printing via its Alert and Affirm procedures. When one of these detects an error, it records it in a data structure that is inside the AlertLogPkg. When the test completes, the test writer calls ReportAlerts and a pass/fail report is produced.

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