Microchip Technology SW006022-1N Data Sheet
Built-in Functions
2012 Microchip Technology Inc.
DS52071B-page 279
F.2
BUILT-IN FUNCTION DESCRIPTIONS
This section describes the programmer interface to the compiler built-in functions. Since the functions are
“built in”, there are no header files associated with them. Similarly, there are no command-line switches
associated with the built-in functions – they are always available. The built-in function names are chosen
such that they belong to the compiler’s namespace (they all have the prefix __
“built in”, there are no header files associated with them. Similarly, there are no command-line switches
associated with the built-in functions – they are always available. The built-in function names are chosen
such that they belong to the compiler’s namespace (they all have the prefix __
builtin_
), so they will not
conflict with function or variable names in the programmer’s namespace.
__builtin_addab
Description:
Add accumulators A and B with the result written back to the specified accumulator. For
example:
volatile register int result asm("A");
example:
volatile register int result asm("A");
volatile register int B asm("A");
result =
__builtin_addab(result,B);
will generate:
add A
add A
Prototype:
int
__builtin_addab(int Accum_a, int Accum_b);
Argument:
Accum_a
First accumulator to add.
Accum_b
Second accumulator to add.
Return Value:
Returns the addition result to an accumulator.
Assembler Operator/
Machine Instruction:
Machine Instruction:
add
Error Messages
An error message will be displayed if the result is not an accumulator register.
__builtin_add
Description:
Add value to the accumulator specified by result with a shift specified by literal shift. For
example:
volatile register int result asm("A");
example:
volatile register int result asm("A");
int value;
result =
__builtin_add(result,value,0);
If value is held in w0, the following will be generated:
add w0, #0, A
add w0, #0, A
Prototype:
int
__builtin_add(int Accum,int value,
const int shift);
Argument:
Accum
Accumulator to add.
value
Integer number to add to accumulator value.
shift
Amount to shift resultant accumulator value.
Return Value:
Returns the shifted addition result to an accumulator.
Assembler Operator/
Machine Instruction:
Machine Instruction:
add
Error Messages
An error message will be displayed if:
• the result is not an accumulator register
• the result is not an accumulator register
• argument 0 is not an accumulator
• the shift value is not a literal within range