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Segment Naming Conventions

Objects generated by the Cx51 Compiler (program code, program data, and constant data) are stored in segments which are units of code or data memory. A segment may be relocatable or may be absolute. Each relocatable segment has a type and a name. This section describes the conventions used by the Cx51 Compiler for naming these segments.

Segment names include a module_name which is the name of the source file in which the object is declared. In order to accommodate a wide variety of existing software and hardware tools, all segment names are converted and stored in uppercase.

Each segment name has a prefix that corresponds to the memory type used for the segment. The prefix is enclosed in question marks (?). The following is a list of the standard segment name prefixes:

Segment
Prefix
Memory
Type
Description
?PR? program Executable program code
?CO? code Constant data in program memory
?BI? bit Bit data in internal data memory
?BA? bdata Bit-addressable data in internal data memory
?DT? data Internal data memory
?FD? far Far memory (RAM space)
?FC? const far Far memory (constant ROM space)
?ID? idata Indirectly-addressable internal data memory
?PD? pdata Paged data in external data memory
?XD? xdata Xdata memory (RAM space)
?XC? const xdata Xdata memory (constant ROM space)

The segment name is assigned based on the memory model of the function.

Small Model Segment Naming Conventions

Information Segment Type Segment Name
Program code code ?PR?function_name?module_name
Local variables data ?DT?function_name?module_name
Local bit variables bit ?BI?function_name?module_name

Compact Model Segment Naming Conventions

Information Segment Type Segment Name
Program code code ?PR?function_name?module_name
Local variables pdata ?PD?function_name?module_name
Local bit variables bit ?BI?function_name?module_name

Large Model Segment Naming Conventions

Information Segment Type Segment Name
Program code code ?PR?function_name?module_name
Local variables xdata ?XD?function_name?module_name
Local bit variables bit ?BI?function_name?module_name
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