SW500008 Microchip Technology, SW500008 Datasheet - Page 86

• Manufacturer Part Number: SW500008
• Description: PICC-18 STD
• Manufacturer: Microchip Technology
• Type: Compilerr
• Series: PIC18r

Specifications of SW500008

• Supported Families: PIC18
• Core Architecture: PIC
• Software Edition: Standard
• Kit Contents: Software And Docs
• Mcu Supported Families: PIC18
• Tool Function: Compiler
• Tool Type: Compiler
• Lead Free Status / RoHS Status: Not applicable / RoHS Compliant
• For Use With/related Products: PIC18 Series
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 015; 778-1001; 778-1001

Mixing C and Assembler Code
3.11.2.1 Accessing special function register names from assembler
If writing separate assembly modules, SFR definitions will not automatically be present. If writing
assembler code from within a C module, SFRs may be accessed by referring to the symbols defined
by the chip-specific C header files. Whenever you include <htc.h> into a C module, all the available
SFRs are defined as absolute C variables. As the contents of this file is C code, it cannot be included
into an assembler module, but assembler code can uses these definitions. To use a SFR in in-line
assembler code from within the same C module that includes <htc.h>, simply use the symbol with
an underscore character prepended to the name. For example:
Alternately, an assembler equivalent of htc.h is provided. If an assembler source includes the file
aspic18.h, equivalent assembler definitions of the devices’ SFRs will be available.
3.11.3 #asm, #endasm and asm()
PIC18 instructions may also be directly embedded “in-line” into C code using the directives #asm,
#endasm or the statement asm().
are to be embedded into the assembly output of the code generator. The #asm and #endasm construct
is not syntactically part of the C program, and thus it does not obey normal C flow-of-control rules,
however you can easily include multiple instructions with this form of in-line assembly.
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The #asm and #endasm directives are used to start and end a block of assembly instructions which
C identifiers are assigned different symbols in the output assembly code so that an as-
sembly identifier cannot conflict with an identifier defined in C code. If assembly pro-
grammers choose identifier names that do not begin with an underscore, these identifiers
will never conflict with C identifiers. Importantly, this implies that the assembly identi-
fier, i, and the C identifier i relate to different objects at different memory locations.
#include <htc.h>
void main(void)
{
}
PORTA = 0x55;
asm("movlw 0xAA");
asm("movwf _PORTA");
...
C Language Features