Keil Software — Cx51 Compiler User’s Guide |
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Chapter 3. Language Extensions
The Cx51 compiler provides several extensions to ANSI Standard C to support the elements of the 8051 architecture. These include extensions for:
Memory Areas
Memory Types
Memory Models
Memory Type Specifiers
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Variable Data Type Specifiers |
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Bit Variables and Bit-addressable Data |
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Special Function Registers
Pointers
Function Attributes
The following sections describe each of these in detail.
Keywords
To facilitate many of the features of the 8051, the Cx51 compiler adds a number of new keywords to the scope of the C language:
_at_ |
far |
sbit |
alien |
idata |
sfr |
bdata |
interrupt |
sfr16 |
bit |
large |
small |
code |
pdata |
_task_ |
compact |
_priority_ |
using |
data |
reentrant |
xdata |
You may disable these extensions using the NOEXTEND control directive. Refer to “Chapter 2. Compiling with the Cx51” on page 17 for more information.