C51: MIXING C AND ASSEMBLY

ÒÔÏÂÈ«ÎÄתÔØ×Ôhttp://www.keil.com/support/docs/1671.htm                     Copyright © 2010 Keil™, An ARM® Company.
Information in this article applies to:
C51 Version 6.02
µVision Version 2.06
QUESTION
Do you have any examples of how to mix C and assembly?
ANSWER
The following example program shows how to mix C and assembly in your 8051 programs.
This example starts with a MAIN C function which calls a routine in assembly which then calls a C function.
The MAIN C module appears as follows:
extern void a_func (void);
void main (void)
{
a_func ();
}
The function a_func is an assembly routine:
NAME A_FUNC
?PR?a_func?A_FUNC SEGMENT CODE
EXTRN CODE (c_func)
PUBLIC a_func
RSEG ?PR?a_func?A_FUNC
a_func:
USING 0
LCALL c_func
RET
END
Note that this assembly routine calls c_func which is a C function:
void c_func (void)
{
}
The actual code for the assembly module was generated using the SRC pragma and the following C source file:
extern void c_func (void);
void a_func (void)
{
c_func ();
}
You may download C2ASM2C.ZIP from the Keil web site.
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