 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 AppendixProgram Objects
Program objects include the code generated for C program functions by the Cx51 Compiler. Each function in a source module is assigned a separate code segment using the ?PR?function_name?module_name naming convention. For example, the function error_check in the file SAMPLE.C would result in a segment name of ?PR?ERROR_CHECK?SAMPLE.
Names for reentrant functions and functions with register parameters are prefixed with special characters to differentiate them from standard functions and to avoid run-time errors when invoking them.
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void func (void) ...
Names of functions that have no arguments or whose arguments are not passed in registers are not modified. This example has a name of FUNC and a segment name of ?PR?FUNC?FILENAME. -
void func1 (char x) ...
Names of functions whose arguments are passed in registers are prefixed with the underscore character ('_'). This example has a name of _FUNC1 and a segment name of ?PR?_FUNC1?FILENAME. -
void func2 (void) reentrant ...
Names of reentrant functions are prefixed with "_?". This example has a name of _?FUNC2 and a segment name of ?PR?_?FUNC2?FILENAME.
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