LX51: LOCATING CONSTANT (CODE) VARIABLES IN A CODE BANK

Information in this article applies to:

• C51 Version 6.32a and Later

QUESTION

How do I locate a constant variable in a code bank using the Extended Linker ( LX51 ) ? I have a source file with a table declared as follows:

unsigned char const code table [10] =
  { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j' };

When I compile and link, the functions in this source file are located in the correct bank, but the table is located in the common area.

ANSWER

When you compile a source file (for example FBANK1.C), the compiler creates program segments for your functions and code segments for your code-based variables. Each function is located in a segment named ?PR?function_name?source_file_name. All code variables are located in a segment named ?CO?source_file_name. This is also true for literal strings.

The linker has commands that let you automatically locate all of the program code from a source file in a code bank. However, the code segments from that file are NOT located in the code bank. You must do that manually.

To locate the code variables in a particular bank, link using a similar command line:

LX51 FBANK1.OBJ,B.OBJ SEGMENTS (?CO?FBANK1(B1:0x8000)) ...

If you use the µVision IDE, enter the following in the User Segment box in the LX51 Locate dialog box.

?CO?FBANK1 (B1:0x8000)

This locates the code variables and string literals from FBANK1.C in BANK1.

MORE INFORMATION

• Refer to SEGMENTS in the LX51 User's Guide.

SEE ALSO

• C51: CREATING CODE BANKING PROGRAMS
• BL51: USING FUNCTION POINTERS WITH CODE BANKING
• C51: INDIRECT FUNCTION CALLS WITH CODE BANKING
• C51: CALCULATING CODE SPACE FOR BANK SWITCHING
• µVision1: SPECIFYING CODE BANKS FOR BANK SWITCHING
• BL51: THE CODE BANKING MECHANISM

FORUM THREADS

The following Discussion Forum threads may provide information related to this topic.

• how to easily locate constant in bank easily?
• _at_ problem

Last Reviewed: Friday, July 15, 2005