qr code reader c# windows phone 8.1 WAIT ON Signal in Visual C#

Read QR Code ISO/IEC18004 in Visual C# WAIT ON Signal

WAIT ON Signal
QR-Code Decoder In Visual C#.NET
Using Barcode recognizer for VS .NET Control to read, scan QR Code 2d barcode image in .NET framework applications.
www.OnBarcode.com
Recognizing QR Code In C#.NET
Using Barcode recognizer for Visual Studio .NET Control to read, scan read, scan image in VS .NET applications.
www.OnBarcode.com
Three
Scanning Bar Code In C#
Using Barcode scanner for Visual Studio .NET Control to read, scan bar code image in .NET framework applications.
www.OnBarcode.com
Recognize Bar Code In C#.NET
Using Barcode scanner for .NET framework Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
We have already seen an example of the first type in the previous process example The WAIT ON signal clause specifies a list of one or more signals that the WAIT statement will wait for events upon If any signal in the signal list has an event occur on it, execution continues with the statement following the WAIT statement Here is an example:
Recognizing Denso QR Bar Code In Visual C#.NET
Using Barcode recognizer for Visual Studio .NET Control to read, scan QR Code image in Visual Studio .NET applications.
www.OnBarcode.com
QR Reader In Visual Studio .NET
Using Barcode decoder for ASP.NET Control to read, scan QR Code 2d barcode image in ASP.NET applications.
www.OnBarcode.com
WAIT ON a, b;
Reading QR Code In .NET Framework
Using Barcode reader for Visual Studio .NET Control to read, scan QR Code JIS X 0510 image in .NET framework applications.
www.OnBarcode.com
QR Code Scanner In Visual Basic .NET
Using Barcode recognizer for Visual Studio .NET Control to read, scan QR Code image in VS .NET applications.
www.OnBarcode.com
When an event occurs on either a or b, the process resumes with the statement following the WAIT statement
Read Barcode In C#.NET
Using Barcode scanner for VS .NET Control to read, scan bar code image in .NET framework applications.
www.OnBarcode.com
ECC200 Reader In C#
Using Barcode scanner for VS .NET Control to read, scan Data Matrix ECC200 image in VS .NET applications.
www.OnBarcode.com
WAIT UNTIL Expression
Recognizing GTIN - 12 In C#
Using Barcode reader for .NET framework Control to read, scan UPC Symbol image in Visual Studio .NET applications.
www.OnBarcode.com
Decoding Bar Code In Visual C#.NET
Using Barcode decoder for .NET Control to read, scan bar code image in .NET applications.
www.OnBarcode.com
The WAIT UNTIL boolean_expression clause suspends execution of the process until the expression returns a value of true This statement effectively creates an implicit sensitivity list of the signals used in the expression When any of the signals in the expression have events occur upon them, the expression is evaluated The expression must return a boolean type or the compiler complains When the expression returns a true value, execution continues with the statement following the WAIT statement Otherwise, the process continues to be suspended For example:
Scan USPS POSTNET Barcode In Visual C#.NET
Using Barcode decoder for .NET Control to read, scan Postnet 3 of 5 image in .NET framework applications.
www.OnBarcode.com
UPC Symbol Recognizer In None
Using Barcode reader for Excel Control to read, scan UPC Code image in Excel applications.
www.OnBarcode.com
WAIT UNTIL (( x * 10 ) < 100 );
Read UCC - 12 In .NET
Using Barcode recognizer for ASP.NET Control to read, scan UCC - 12 image in ASP.NET applications.
www.OnBarcode.com
Scan GS1 - 12 In Java
Using Barcode decoder for Java Control to read, scan UPC Code image in Java applications.
www.OnBarcode.com
In this example, as long as the value of signal x is greater than or equal to 10, the WAIT statement suspends the process or subprogram When the value of x is less than 10, execution continues with the statement following the WAIT statement
Barcode Scanner In VS .NET
Using Barcode decoder for .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
Reading Bar Code In None
Using Barcode recognizer for Microsoft Excel Control to read, scan barcode image in Office Excel applications.
www.OnBarcode.com
WAIT FOR time_expression
Bar Code Scanner In Java
Using Barcode recognizer for Java Control to read, scan bar code image in Java applications.
www.OnBarcode.com
Reading QR Code JIS X 0510 In VS .NET
Using Barcode scanner for ASP.NET Control to read, scan Quick Response Code image in ASP.NET applications.
www.OnBarcode.com
The WAIT FOR time_expression clause suspends execution of the process for the time specified by the time expression After the time specified in the time expression has elapsed, execution continues on the
Sequential Processing
statement following the WAIT statement A couple of examples are shown here:
WAIT FOR 10 ns; WAIT FOR ( a * ( b + c ));
In the first example, the time expression is a simple constant value The WAIT statement suspends execution for 10 nanoseconds After 10 nanoseconds has elapsed, execution continues with the statement following the WAIT statement In the second example, the time expression is an expression that first must be evaluated to return a time value After this value is calculated, the WAIT statement uses this value as the time value to wait for
Multiple WAIT Conditions
The WAIT statement examples we have examined so far have shown the different options of the WAIT statement used separately The different options can be used together A single statement can include an ON signal, UNTIL expression, and FOR time_expression clauses Following is an example:
WAIT ON nmi,interrupt UNTIL ((nmi = TRUE) or (interrupt = TRUE)) FOR 5 usec;
This statement waits for an event on signals nmi and interrupt and continues only if interrupt or nmi is true at the time of the event, or until 5 microseconds of time has elapsed Only when one or more of these conditions are true does execution continue When using a statement such as this:
WAIT UNTIL (interrupt = TRUE) OR ( old_clk = 1 );
be sure to have at least one of the values in the expression contain a signal This is necessary to ensure that the WAIT statement does not wait forever If both interrupt and old_clk are variables, the WAIT statement does not reevaluate when these two variables change value (In fact, the variables cannot change value because they are declared in the suspended process) Only signals have events on them, and only signals can cause a WAIT statement or concurrent signal assignment to reevaluate
WAIT Time-Out
Three
There are instances while designing a model when you are not sure that a condition will be met To prevent the WAIT statement from waiting forever, add a time-out clause The time-out clause allows execution to proceed whether or not the condition has been met Be careful, though, because this method can cause erroneous behavior unless properly handled The following example shows this problem:
ARCHITECTURE wait_example of wait_example IS SIGNAL sendB, sendA : std_logic; BEGIN sendA <= 0 ; A : PROCESS BEGIN WAIT UNTIL sendB = 1 ; sendA <= 1 AFTER 10 ns; WAIT UNTIL sendB = 0 ; sendA <= 0 AFTER 10 ns; END PROCESS A; B : PROCESS BEGIN WAIT UNTIL sendA = 0 ; sendB <= 0 AFTER 10 ns; WAIT UNTIL sendA = 1 ; sendB <= 1 AFTER 10 ns; END PROCESS B; END wait_example;
This architecture has two processes that communicate through two signals, sendA and sendB This example does not do anything real but is a simple illustration of how WAIT statements can wait forever, a condition commonly referred to as deadlock During simulator initialization, all processes are executed exactly once This allows the processes to always start at a known execution point at the start of simulation In this example, the process labeled A executes at startup and stops at the following line:
WAIT UNTIL sendB = 1;
The process labeled B also executes at startup Execution starts at the first line of the process and continues until this line:
Copyright © OnBarcode.com . All rights reserved.