Implement malloc()

Hi,
Can anyone suggest any idea or some C code to implement malloc function. The point is how will you find the amount of memory present in the heap and allocate it.
Please try to explain the code as I am sure it would be complicated.
Thanks.

Dynamic 2D array of longs:

Code:

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// Malloc returns a pointer to the beginning of the array you just initialised
// (long*) is a typecast telling the compiler that malloc is returning a pointer to an array of longs
long *pointer = (long*)malloc(length * width * sizeof(long));

if (pointer == NULL) {
    // Do something error-like (malloc returns null if failed to allocate memory)
}

//From now on we can use it like a 1-dimensional array, use this formula to write a 2D position:
pointer[(y * width) + x] = value;

// When done, you MUST do this:
free(pointer);

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Hi tigs,
Thanks for responding. However I think you didnt get my question. I want to know how is the malloc function actually written in the system library. I mean what would be the contents/definition of the function. How would the function figure out how much heap memory is remaining and how would it allocate it.
Thanks.

Quote:

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Originally posted by rahuls
Hi tigs,
Thanks for responding. However I think you didnt get my question. I want to know how is the malloc function actually written in the system library. I mean what would be the contents/definition of the function. How would the function figure out how much heap memory is remaining and how would it allocate it.
Thanks.

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We are not allowed to know that...
It's up to each compiler.

>The point is how will you find the amount of memory present in the heap and allocate it.
You would use a system level function or other implementation/system dependent method to acquire core memory from the free store. malloc is one of the functions that will probably be wildly different for every system.

-Prelude

Here's how GNU did it.

gg