 Cx51 User's Guide | |
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Cx51 User's Guide
Cx51 Introduction Compiling Programs Language Extensions Preprocessor Advanced Programming Customization Files
Startup Code Variable Initialization Code XBANKING.A51 Basic I/O Memory Allocation Optimizer Optimizer Options General Optimizations 8051-Specific Optimizations Global Register Coloring Segment Naming Conventions Data Objects Program Objects Parameters and Local Variables Interfacing C to Assembler Global Variables Function Parameters Passing in Memory Passing in Registers Function Return Values Using the SRC Directive Register Usage Overlaying Segments Small Model Example Compact Model Example Large Model Example Interfacing C programs to PL/M-51 Data Storage Formats Bit Variables 1-Byte Scalars 2-Byte Scalars 4-Byte Scalars Generic and Far Pointers Floating-point Numbers Floating-point Errors Absolute Memory Locations Absolute Access Macros Linker Location Controls The _at_ Keyword Debugging 8051 Derivatives Error Messages Library Reference AppendixData Objects
Data objects are the variables and constants you declare in your C programs. The Cx51 Compiler generates a separate segment for each memory type for which a variable is declared. The following table lists the segment names generated for different variable data objects.
| Segment Name | Description |
|---|---|
| ?BA?module_name | Bit-addressable data objects |
| ?BI?module_name | Bit objects |
| ?CO?module_name | Constants (strings and initialized variables) |
| ?DT?module_name | Objects declared in data |
| ?FC?module_name | Objects declared in const far (requires OMF2 directive) |
| ?FD?module_name | Objects declared in far (requires OMF2 directive) |
| ?ID?module_name | Objects declared in idata |
| ?PD?module_name | Objects declared in pdata |
| ?XC?module_name | Objects declared in const xdata (requires OMF2 directive) |
| ?XD?module_name | Objects declared in xdata |
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