Ages ago I worked with a system where malloc(0) incremented a counter and returned -1.
free(-1) decremented the counter.
This way you could check for leaks :p
replies(3):
free(-1) decremented the counter.
This way you could check for leaks :p
On most platforms an implementation could just return adjacent addresses from the top half of the address space. On 32-bit platforms it doesn't take long to run out of such address space however, and you don't want to waste the space for a bitmap allocator. I suppose you could just use a counter for each 64K region or something, so you can reuse it if the right number of elements has been freed ...
I know I've seen that somewhere, but may I ask what standard you're referring to?
If I recall correctly, this was an archaic stackless microcontroller. The heap support was mostly a marketing claim.
Of course, microcontrollers and the like can have somewhat eccentric implementations of languages of thing and perhaps aren't strictly compliant, and frankly even standard compliant stuff like "int can be 16 bits" might surprise some code that doesn't expect it.