Addressing memory in a simulator

Writing a simple 32 bit simulator (in c++) but managing the memory is throwing me into a loop.

My plan was to have a 2D array, the first being pointers each pointing to blocks of memory which are created on first read/write into the block.

The issue I am having is how to address it properly, if I need, for example, 2^16 bits of addressable memory does that mean that.

• I need 2048 words worth of memory (where each word is a 32bit uint)


• Which could be split into 64 blocks of 32 words (each block being 1024 bytes, or 8192 bits)

I am under the impression this would appear something like as follows

    uint32_t* m[64];
    // When first read or write into a block create as follows
    m[block] = new uint32_t[32];

This would mean the last accessible address would be 0xfffc (as 0x10000 is the total amount of addresses).

Now, if this is all correct (which I am not certain it is) I think actually getting to the memory would be as follows

    uint32_t whichBlock = addr / (32 * 4);
    uint32_t blockLoc = (addr % 32) / 4;

This seems to work for, say for example 0x80 as the address as whichBlock would be 1 and blockLoc would b 0 (i.e. the 1st word in the 2nd block) but is obviously wrong when the address is something like 0xff8c which gives whichBlock as 511 and blockLoc as 3.

Obviously I have gone completely wrong with my calculations somewhere, but I cant figure out where!