SW006012 Microchip Technology, SW006012 Datasheet - Page 118

• Manufacturer Part Number: SW006012
• Description: C COMPILER FOR DSPIC30F FAMILY
• Manufacturer: Microchip Technology
• Type: MPLAB® C30 Compilerr
• Series: PIC24 & DsPICr

Specifications of SW006012

• Supported Families: PIC24, DsPIC30F And DsPIC33F
• Core Architecture: PIC, DsPIC
• Kit Contents: Software And Docs
• Mcu Supported Families: PIC24 MCUs And DsPIC DSCs
• Tool Type: Compiler
• Processor Series: PIC24, dsPIC
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• For Use With/related Products: dsPIC30F
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

MPLAB
DS51284F-page 112
®
C30 User’s Guide
EXAMPLE 8-1:
/*
** file: ex1.c
*/
extern unsigned int asmVariable;
extern void asmFunction(void);
unsigned int cVariable;
void foo(void)
{
}
The file ex2.s defines asmFunction and asmVariable as required for use in a
linked application. The assembly file also shows how to call a C function, foo, and how
to access a C defined variable, cVariable.
;
;
;
_asmFunction:
_main:
_asmVariable: .space 2
In the C file, ex1.c, external references to symbols declared in an assembly file are
declared using the standard extern keyword; note that asmFunction, or
_asmFunction in the assembly source, is a void function and is declared
accordingly.
In the assembly file, ex1.s, the symbols _asmFunction, _main and _asmVariable
are made globally visible through the use of the .global assembler directive and can
be accessed by any other source file. The symbol _main is only referenced and not
declared; therefore, the assembler takes this to be an external reference.
The following MPLAB C30 example shows how to call an assembly function with two
parameters. The C function main in call1.c calls the asmFunction in call2.s
with two parameters.
.end
asmFunction();
asmVariable = 0x1234;
.text
.global _asmFunction
mov #0,w0
mov w0,_cVariable
return
.global _begin
call _foo
return
.bss
.global _asmVariable
.align 2
file: ex2.s
MIXING C AND ASSEMBLY
© 2007 Microchip Technology Inc.