1 C Programming for Embedded Systems. Data RAM Pointer Types ...

P. Klimo Sep 2010
Assessing Individual bits:
struct foo {
// Declare foo as a structure type
unsigned lo:1; // bit 0
unsigned dummy: 6; // bits 1 to 6
unsigned hi:1; // bit 7
} *ptrfoo; // Declare ptrfoo as a pointer to structure type foo
struct foo PortA;
// Define PortA as a structure foo
PortA.hi =0; // Initiate bit 7 of PortA to 0
ptrfoo=&PortA;
// Set pointer ptrfoo to point at PortA
ptrfoo->lo = 1; // Initiate bit 0 of PortA to 1
Macros:
#define TWO 2
// Define a constant macro
int y = TWO*3;
#define multiplyByTwo(x) 2*(x) // Define a “ function” macro
y = multiplyByTwo(3);
Typedef:
int myFunc tion(int r);
// Declare a function (defined elsewhere)
int k = 6;
typedef int (*Func)(int a) ptrFunc;
ptrFunc = myFunction;
// Define ptrFunc as a pointer to a function type
// Point to myFunction
ptrFunc(k); // Call myFunc tion with argument 6
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