MATLAB XPC TARGET 4 - DEVICE DRIVERS User's Guide download pdf (Page 75)

Accessing Registers

In this section...

“I/O Space” on page 6-7

“Memory-Mapped Space” on page 6-7

I/O Space

For registers in I/O space, use the xPC Target I/O read and write functions:

• Read functions

uint32_T xpcInpDW(uint16_T port ); // read a 32 bit word

uint16_T xpcInpW(uint16_T port ); // read a 16 bit word

uint8_T xpcInpB(uint16_T port ); // read an 8 bit byte

• Write fun

ctions

void xpc

OutpDW(uint16_T port, uint32_T value ); // writ e 32 bits

void xpc

OutpW(uint16_T port, uint16_T value ); // write 16 bits

void xpc

OutpB(uint8_T port, uint8_T value ); // write a byte

TheportaddressisthevaluereturnedintheBaseAddr ess array.

Memory-Mapped Space

For registers in memory-mapped space, access them by dereferencing

through a pointer that contains the virtual address returned by the

xpcReserveMemoryRegion function. Because modern compilers have

aggressive optimizers, you must declare the pointer to be volatile. Doing

so ensures that the compiler does not optimize out reads a nd writes using

that pointer. The following pseudocode illustrates t h is using two me t ho ds:

structure and array.

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MATLAB XPC TARGET 4 - DEVICE DRIVERS User's Guide Page 75