[cnvogel]

It's still non-esoteric today:

http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc....

ARM Cortex M4 supports adressing individual bits (often registers of hardware peripherals) of memory locations as one additional memory location writing to, or reading from a single bit.

e.g., from the examples of said infocenter url:

   *(uint32_t*)0x20000000 |= (1<<7)
   *(uint32_t*)0x20000000 &= ~(1<<7)

should be equivalent to

   *(uint32_t*)0x2200001C = 1;
   *(uint32_t*)0x2200001C = 0;

Also Analog Sharc DSPs (which, I think, still are being sold with this architecture, and still used, even though I've used them only 10 years ago) alias their memory four times, depending if you want to access it as 16bit, 32bit, 48 or 64bit data.

[Taniwha]

I think you're missing 'volatile's in your casts

[cnvogel]

The examples should only view the bit/address mapping, not be a complete example on how to access memory mapped peripherals.

[foxhill]

why would you need that in this case?