barcode reader project in asp.net Structures, Pointers, and Arrays in Software

Generation QR Code 2d barcode in Software Structures, Pointers, and Arrays

Structures, Pointers, and Arrays
Scanning QR Code ISO/IEC18004 In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
Print QR Code ISO/IEC18004 In None
Using Barcode creation for Software Control to generate, create QR Code image in Software applications.
If you have been trained in a classical programming environment, you are probably very comfortable with working with structures and pointers. Complicating matters, you may want to use these programming constructs with arrays. Developing applications with these features is possible for the PIC microcontroller using MPLAB s assembler, although they are used rarely because of the lack of large contiguous le register space in most of the PIC microcontroller device families and the dif culty in working with the PIC microcontroller processor. Despite these dif culties, structures, pointers, and arrays can be created in PIC microcontroller assembly language, although using them will be somewhat more complex than what you are used to with other processors.
QR Code Scanner In None
Using Barcode scanner for Software Control to read, scan read, scan image in Software applications.
Paint QR Code ISO/IEC18004 In C#
Using Barcode creation for VS .NET Control to generate, create QR Code image in VS .NET applications.
ASSEMBLY-LANGUAGE SOFTWARE TECHNIQUES
Paint QR Code ISO/IEC18004 In .NET
Using Barcode printer for ASP.NET Control to generate, create QR Code image in ASP.NET applications.
Quick Response Code Generator In .NET
Using Barcode creation for .NET framework Control to generate, create QR Code ISO/IEC18004 image in .NET framework applications.
The three programming constructs presented here all will require use of the FSR register and the bank select features of the PIC microcontroller. In actuality, this will be the most challenging and sophisticated use of the FSR that you will see in this book, and you may want to try out the code snippets provided here to see exactly how they work. The MPLAB assembler does not have an explicit structure directive that can be used to de ne a structure within the application. In other assemblers and compilers, the structure directive is used to set up a single data type consisting of a number of other data types. In C, a structure is de ned like
Quick Response Code Drawer In Visual Basic .NET
Using Barcode encoder for Visual Studio .NET Control to generate, create QR Code ISO/IEC18004 image in VS .NET applications.
Code128 Generation In None
Using Barcode generation for Software Control to generate, create Code-128 image in Software applications.
struct VarStruct { int varA; char varB; char * NextVarStruct; }; // // // // De ne a Structure 16 Bit Variable 8 Bit Variable Pointer to an 8 Bit Variable
Print UCC.EAN - 128 In None
Using Barcode maker for Software Control to generate, create GS1-128 image in Software applications.
UPC-A Supplement 5 Printer In None
Using Barcode generator for Software Control to generate, create UPC Symbol image in Software applications.
When a variable is declared, the structure is used as the data type. In C, a variable de ned from the preceding structure would be declared as
Generate GS1 - 13 In None
Using Barcode printer for Software Control to generate, create UPC - 13 image in Software applications.
Generate Barcode In None
Using Barcode creator for Software Control to generate, create bar code image in Software applications.
struct VarStruct VarValue;
Code-27 Printer In None
Using Barcode creation for Software Control to generate, create Ames code image in Software applications.
Data Matrix Reader In Visual Studio .NET
Using Barcode recognizer for VS .NET Control to read, scan read, scan image in .NET framework applications.
To access the structure elements in VarValue, the element name is added to the variable name with a period or dot (.):
Draw GS1 128 In None
Using Barcode generator for Font Control to generate, create EAN128 image in Font applications.
Draw USS Code 128 In VB.NET
Using Barcode maker for .NET Control to generate, create Code128 image in .NET framework applications.
VarValue.varA = VarValue.varB * 4;
Bar Code Printer In VS .NET
Using Barcode drawer for .NET Control to generate, create bar code image in Visual Studio .NET applications.
Recognize Barcode In Visual Basic .NET
Using Barcode decoder for VS .NET Control to read, scan read, scan image in Visual Studio .NET applications.
In this statement, the structure element varA is loaded with the contents of the structure element varB after it has been multiplied by 4. This capability allows quick and easy structure variable element access and modi cation. This is not a high level language speci c capability; many assemblers allow structures to be de ned and used with structure variables. The MPLAB assembler does not, but you can still specify a structure and use it in MPLAB using the CBLOCK directive. The VarStruct structure shown above can be de ned in MPLAB as
Encoding Bar Code In VB.NET
Using Barcode creation for VS .NET Control to generate, create barcode image in .NET applications.
Recognizing UCC.EAN - 128 In C#
Using Barcode reader for Visual Studio .NET Control to read, scan read, scan image in .NET applications.
; VarStruct De ne CBLOCK 0 varA:2 varB NextVarStruct:2 SizeOfVarStruct ENDC an ; ; ; ; ; MPLAB Structure Start with Offset equal to Zero 16 Bit Variable 8 Bit Variable Pointer to an 8 Bit Variable Set to Number of Bytes of VarStruct
The last entry in the CBLOCK statement above is assigned the number of bytes in the structure and will not be used except for keeping track of the number of bytes required by the structure. The SizeOf built-in C function returns the size of a structure, which is why I chose the identi er used above for this structure function.
STRUCTURES, POINTERS, AND ARRAYS
To declare a structure variable in MPLAB, the CBLOCK directive is used in the declaration
CBLOCK 0x Start : VarValue:SizeOfVarStruct : ENDC ; De ne Variables at File Register
; De ne the Structure Variable
In these CBLOCK statements, VarValue is de ned along with the other variables the size of the structure (as returned by SizeOfVarStruct). For this declaration to work properly, the structure must be de ned before the variable to ensure that SizeOfVarStruct is valid and does not change between the assembly passes. To address the structure elements in the structure variable, the structure element offset (de ned by the rst CBLOCK) is added to the address of the structure variable. To show how this is done, the PIC microcontroller assembly code for the example C statement
VarValue.varA = VarValue.varB * 4;
Copyright © OnBarcode.com . All rights reserved.