175. Template

Question.5

A developer uses a non-type template parameter for hardware addressing:

template<uint32_t BaseAddr>
class GPIO {
public:
   static void setHigh() {
       *(volatile uint32_t*)(BaseAddr + 0x18) = 1;
   }
};

using LED = GPIO<0x40021000>;
LED::setHigh();

What instruction does LED::setHigh() compile to?

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A function call that loads BaseAddr from RAM at runtime
A single direct memory write instruction -- the compiler resolves 0x40021000+0x18=0x40021018 at compile time and stores the literal address
A vtable lookup followed by a write
An indirect write through a pointer variable

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