To be done in C. Please include thorough comments in the code. Make a simple bud

Question

To be done in C. Please include thorough comments in the code.

Make a simple buddy buffer manager with 4 functions for an operating system. This assignment is due June 12, 2017. It will give out buffers from a fixed size area. The available memory for the buffer manager will be initially set to 10 of the maximum buffer sizes (511 words) It will have a function which gives out buffers in sizes (which are powers of 2 less 1) from 7 words to 511 words. The other word in the buffer will be a control word for use by the buffer manager. The requester will provide a block size and the routine will return an address of a buffer (probably for most of you a relative address from the start of an array holding the buffers) or -1 (cannot provide a buffer of that size because of lack of space). Note that the routine may need to split a buffer into two buddies to get a proper sized buffer. This splitting may need to cascade. For example if there are only 511 word blocks available, to get a 7 word block, a 511 word block will have to be split into two 255 word buddy blocks. Then one of the 255 word buddy blocks will have to split into two 127 word buddy blocks, etc. down to two 7 word buddy blocks, one of which will be given to the requester. The returned address will be the word after the control word. The first call to request a buffer will be required to call your initialization routine to set up the linked lists defined below. Another thing to check is a request for illegal block sizes if you get a request for 700 words you need to return an error status (a -2 for illegal request). If, for example, you get a request for a 5 word block, you have an option (but you must be consistent), you can either return a pointer (or index) to a 7 word block or return an error status (a -2 for illegal request).

Explanation / Answer

#include < iostream>

using namespace std,

class buddy,

static buddy*instance;

static std::size_t refcount;

public:static void*operator new(std::size_t nbytes) throw(std::bad_alloc)

if (instance == nullptr)

instance = ::new buddy;

refcount++;

return instance;

}

static void operator delete(void*p)

(

if(--refcount == 0)

{

::delete instance;

instance = nullptr;

}

}

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