barcode reader project in asp.net ASSEMBLY-LANGUAGE SOFTWARE TECHNIQUES in Software

Generator QR Code in Software ASSEMBLY-LANGUAGE SOFTWARE TECHNIQUES

ASSEMBLY-LANGUAGE SOFTWARE TECHNIQUES
QR Code ISO/IEC18004 Scanner In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
QR-Code Printer In None
Using Barcode generator for Software Control to generate, create QR Code 2d barcode image in Software applications.
Many PIC microcontroller applications can use Flash-based parts for application debug or an emulator that can allow changes in source code to be transferred to the application s PIC microcontroller almost immediately. Furthermore, one of the characteristics of Flash memory is that blocks of it can be erased at any time, resulting in large areas of memory that have to be reprogrammed this means that while space can be left for updating the application, it can only be used once. These capabilities basically invalidate the arguments for providing patch space in an application. However, there are some cases where only an EPROM PIC microcontroller part can be used, and there is no emulator available for it. The memory that is going to be used for patch space must be left erased (all bits set if they were to be read back) so that a new set of instructions can be programmed in. In the case of an EPROM PIC, some program memory can be devoted to providing patch code in the application. The typical way to do this is to de ne a block of code inline to the application with a jump around it. The format for this is
Scanning Denso QR Bar Code In None
Using Barcode recognizer for Software Control to read, scan read, scan image in Software applications.
Encoding QR-Code In C#
Using Barcode creation for Visual Studio .NET Control to generate, create QR Code ISO/IEC18004 image in .NET applications.
goto $ + size + 1 variable i = 0 while (i < size) dw 0x3FFF i = i + 1 endw
QR Code JIS X 0510 Drawer In VS .NET
Using Barcode creation for ASP.NET Control to generate, create QR-Code image in ASP.NET applications.
QR Code JIS X 0510 Maker In Visual Studio .NET
Using Barcode creation for .NET framework Control to generate, create Quick Response Code image in VS .NET applications.
In Chap. 10, I will explain the format of the variable, while, and wend directives, but the preceding code de nes a block of program memory size + 1 instructions long that can be loaded with any instructions. The dw 0x03FFF instructions leave each memory untouched and ready to accept patch code. To put instructions into the patchcode space, the rst goto is overwritten with 0x0000, which is the NOP instruction. Following this, the instructions can be programmed into the PIC microcontroller s program memory. To show what I mean, let s go through an example. An application has the statement
QR Code Drawer In Visual Basic .NET
Using Barcode printer for Visual Studio .NET Control to generate, create QR Code ISO/IEC18004 image in VS .NET applications.
Data Matrix ECC200 Encoder In None
Using Barcode creation for Software Control to generate, create Data Matrix image in Software applications.
Result = 47 B</CP>
UCC - 12 Generator In None
Using Barcode creation for Software Control to generate, create USS-128 image in Software applications.
Paint Barcode In None
Using Barcode creator for Software Control to generate, create bar code image in Software applications.
which the developer has coded
Encode UPC-A Supplement 2 In None
Using Barcode creator for Software Control to generate, create UPC Code image in Software applications.
Bar Code Encoder In None
Using Barcode printer for Software Control to generate, create bar code image in Software applications.
movlw 47 subwf B, w movf Result
Intelligent Mail Generation In None
Using Barcode encoder for Software Control to generate, create OneCode image in Software applications.
Barcode Generator In Visual Studio .NET
Using Barcode creation for ASP.NET Control to generate, create bar code image in ASP.NET applications.
When this was entered into the source code, the developer was not sure that it was correct. In case it wasn t, the developer provided three instructions of patch-code space to rewrite the code in case the original code was wrong. The actual source code used for the application was
Code 3/9 Scanner In Visual Basic .NET
Using Barcode recognizer for .NET framework Control to read, scan read, scan image in .NET applications.
Printing USS Code 39 In Java
Using Barcode printer for Eclipse BIRT Control to generate, create Code 3/9 image in Eclipse BIRT applications.
movlw 47 subwf B, w
Recognize Code 128 Code Set B In Visual Studio .NET
Using Barcode recognizer for .NET Control to read, scan read, scan image in VS .NET applications.
Code 128B Generator In None
Using Barcode encoder for Font Control to generate, create Code 128B image in Font applications.
STRUCTURES, POINTERS, AND ARRAYS
Drawing Code 3 Of 9 In None
Using Barcode encoder for Online Control to generate, create Code 39 Full ASCII image in Online applications.
Scanning Barcode In Visual Basic .NET
Using Barcode decoder for .NET Control to read, scan read, scan image in Visual Studio .NET applications.
movwf Result goto $ + 4 dw 0x3FFF dw 0x3FFF dw 0x3FFF
; Jump Over Patch Code
In the course of the application s debug, the developer discovered that the original subtraction method was incorrect and that the use of 47 and B had to be reversed. To try out the code, the original subtraction operation is overwritten with zeros (to make the three instructions nops), along with the goto instruction. Next, the three correct subtraction instructions are programmed in. These seven instructions in program memory become
; current instructions nop nop nop nop movf B, w sublw 47 movf Restart previous instructions ; movlw 47 ; subwf B, w ; movwf Restart ; goto $ + 4 ; dw 0x3FFF ; dw 0x3FFF ; dw 0x3FFF
If you look at the PIC18 s instruction set, you will see that nop instructions can either be 0xFFFF or 0x0000. This allows patch space to be put inline as all 0xFFFF, eliminating the need for jumps around the saved patch area. Of course, to be able to provide patch-code areas, you will need a programmer that can write to speci c addresses with speci c values. The programmers discussed in this book do not have this capability (they are designed to write the entire program memory). Some programmers can be fooled into providing this function by changing the source code so that the old code and jump-over are zeroed out (and become nops) and then are programmed into the PIC microcontroller. Before making the change, the programmer will issue an error message at the start indicating that the PIC microcontroller isn t blank and that you will carry on with the programming regardless.
Copyright © OnBarcode.com . All rights reserved.