Epson S5U1C17001C, Manual

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4-14
EPSOn
S5U1C17001C ManUal
(C COMPilEr PaCkagE fOr S1C17 faMily) (Ver. 1.5.0)
4 SOUrCE filES
4)
long l_local_val = (long)boot;
→
A function name can be used to assign the pointer to the
long
type local variable
l_local_val
.
5)
char c_Global_Val;
void sub()
{
c_Global_Val = (char)boot;
}
→
A function name can be used to assign the pointer to the
c h a r
type global variable
c_Global_Val
except when it is declared.
(6) Function pointers can be used in C sources, note, however, that function pointers cannot be assigned to real type
(
float
/
double
) variables and arrays similar to (5) above.
They can be assigned to integer type variables and arrays.
However, when a global variable/array is declared, a function pointer cannot be assigned at the same time.
If it is not at declaration, a function pointer can be assigned to integer type global variables/arrays.
Integer type local variables/arrays always allow substitution with a function pointer regardless of whether it is
at declaration or not. However, a warning occurs depending on a combination of the address space size and the
type of global/local variable or global/local array.
In 24-bit address space (default condition) or 20-bit address space (when
-mshort-offset
only is specified)
A warning occurs if a function pointer is assigned to a variable/array other than
long
/
unsigned long
data types.
In 16-bit address space (when
-mpointer16
is specified)
A warning occurs if a function pointer is assigned to a variable/array other than
short
/
unsigned
short
/
int
/
unsigned int
data types.
Examples: In 16-bit address space (when
-mpointer16
is specified)
void (* fp_Pt)(void); // Declaration of a function pointer with
// void type return value and argument
1)
short s_Global_Val = (short)fp_Pt;
→
An error occurs if a function pointer is assigned to the global variable
s_Global_Val
when it is
declared.
error: initializer element is not constant
2)
short s_local_val = (short)fp_Pt;
→
A function pointer can be assigned to the
short
type local variable
s_local_val
.
3)
long l_local_val = (long)fp_Pt;
→
Although a function pointer can be assigned to the
long
type local variable
l_local_val
, a
warning will occur.
warning: cast from pointer to integer of different size
4)
short s_Global_Val;
void sub()
{
s_Global_Val = (short)fp_Pt;
}
→
A function pointer can be assigned to the
short
type global variable
s_Global_Val
except
when it is declared.