如何 map 一个 32 位 memory 地址来自 CPU 到 Z0D69B4957F06CD818D7BF3D61980E291Z 在 Z0D61F8374D141D412F78ZB3

Question

So I have an implementation of a cache at a smaller level using Queues and I have a trace file that geneartes streams of reads and writes in a fashion generated by CPU eg. read location 0x20000064 (32 bit address). In my main.c I have implemented a global memory using array of specific dimensions to emulate the behavior of RAM memory. However the problem is, I am decoding tha 32 bit address which accesses memory to get the tag and offset bits for cache bu the array address indexes start from 0 to 1023 eg for int array[1024].How do I map here the 32 bit address to the address like I want the indexing to start from 20000000 and till lets say 30000000 and not from 0 to 10000000.Some what similar to a hash table.

Answer 1

If I understand correctly what you're trying to do, you will want to take advantage of the fact that most memory addresses are unused. The address space on a modern processor is enormous, but I doubt the test data you will use for your application will use more than a small fraction of this. Perhaps you could first understand the page size (eg 4096 bytes) and then create a hash of the base address of each page to an array of storage for that page. Then when you need to lookup an address, you calculate the page base address with "address-address%page_size", look up the array in your hash of pages and then the value you want is at "(address%page_size)" within that array. It's a bit hard to tell what you want from your question, but I hope this suggestion gives you something to work with.