|
||
| Products Download Events Support Videos | ||
Technical Support
On-Line Manuals
C251 User's Guide
C251 Introduction
Compiling Programs
Language Extensions
Keywords
Memory Areas
Program Memory
Internal Data Memory
External Data Memory
Near Memory
Far Memory
Huge Memory
SFR Memory
Memory Models
Tiny Model
XTiny Model
Small Model
XSmall Model
Large Model
Memory Types
Implicit Memory Types
bdata
code
data
ebdata
far
huge
idata
near
xdata
Data Types
Special Function Registers
sfr
sfr16
sbit
Bit-Addressable Objects
bit
Standard C Types
void
char
int
enum
float
double
Type Modifiers
signed
unsigned
short
long
Type Qualifiers
const
volatile
Storage Classes
auto
register
extern
static
Absolute Variable Location
Pointers
Memory Type in Pointer Declarations
Pointer Conversions
Function Declarations
Memory Models
Register Banks
Interrupt Functions
Reentrant Functions
Alien (PL/M-51) Function
Real-Time Function Tasks
Attributes
alias("target")
aligned(n)
noreturn
Preprocessor
Advanced Programming
Error Messages
Library Reference
Appendix
Function Declarations
The C251 Compiler provides a number of extensions for standard C function declarations. These extensions allow to:
- Declare a function as an interrupt procedure
- Set the register bank
- Select the memory model
- Declare a reentrant function
- Declare alien functions
You can include these extensions or attributes (many can be combined) in the function declaration. Use the following format for declaring functions:
〚return_type〛 funcname (〚args〛) 〚{small | large}〛
〚__attribute__ ((attrib_spec))〛
〚reentrant〛
〚interrupt n〛
〚using y〛
where:
| return_type | is the type of the value returned from the function. If no type is specified, int is assumed. |
| funcname | is the name of the function. |
| args | is the argument list for the function. |
| small | explicitly defines the function uses the small memory model. |
| large | explicitly defines the function uses the large memory model. |
| __attribute__ | is a keyword followed by an attribute specification. Refer to Attributes for more information. |
| attrib_spec | is an attribute specification enclosed by double-brackets. For example, noreturn. Refer to Attributes for the complete list of attributes specifications. |
| reentrant | indicates that the function is recursive or reentrant. |
| interrupt | indicates that the function is an interrupt function. |
| n | is the interrupt number. |
| using | specifies which register bank the function uses. |
| y | is the register bank number. |
Descriptions of these attributes and other features are described in detail in the following topics.
ProductsDevelopment Tools |
Hardware & Collateral |
Downloads |
Support |
Contact |
 |
||||