Struct riscy::memory::PagedMemory

pub struct PagedMemory { /* private fields */ }

PagedMemory is the implementation of the Memory interfaced used by the riscy binary.

Whenever an address is first accessed, it will allocate a 4KiB page containing that address. The pages are stored in a BTreeMap which making finding the correct page fast and efficient. Each page is represented by contiguous block of memory.

The full 32-bit address space of a RISC-V machine is 4GiB in size. Using on-demand pages like this means that the host system usually only allocates a bit more memory than it actually uses.

Once a page is allocated, it is never de-allocated.

When reading from uninitilized memory, PagedMemory will return a value of 0x00 for that byte. This is unrealistic in physical memory, where you get whatever junk the operating system or the hardware had left over. However, getting zeroed-out memory makes it easier to debug when there is a problem.

Implementations

impl PagedMemory

pub fn new() -> PagedMemory

Create a new PagedMemory with no allocated pages.

Trait Implementations

impl Debug for PagedMemory

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Memory for PagedMemory

fn store_byte(&mut self, addr: Addr, value: u8)

fn load_byte(&self, addr: Addr) -> u8

fn load_halfword(&self, addr: Addr) -> u16

fn load_word(&self, addr: Addr) -> u32

fn store_halfword(&mut self, addr: Addr, value: u16)

fn store_word(&mut self, addr: Addr, value: u32)

fn memcpy(&mut self, base_addr: Addr, buf: &[u8])