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|
use bedrock_core::*;
type Page = [u8; 256];
macro_rules! fn_read_head {
($fn_name:ident($offset:ident, $address:ident)) => {
pub fn $fn_name(&mut self) -> u8 {
let page_i = (self.$offset + (self.$address / 256)) as usize;
let byte_i = (self.$address % 256) as usize;
self.$address = self.$address.wrapping_add(1);
match self.pages.get(page_i) {
Some(page) => page[byte_i],
None => 0,
}
}
};
}
macro_rules! fn_write_head {
($fn_name:ident($offset:ident, $address:ident)) => {
pub fn $fn_name(&mut self, byte: u8) {
let page_i = (self.$offset + (self.$address / 256)) as usize;
let byte_i = (self.$address % 256) as usize;
self.$address = self.$address.wrapping_add(1);
match self.pages.get_mut(page_i) {
Some(page) => page[byte_i] = byte,
None => if page_i < self.provisioned {
self.pages.resize(page_i + 1, [0; 256]);
self.pages[page_i][byte_i] = byte;
}
}
}
};
}
pub struct MemoryDevice {
pub limit: u16, // maximum provisionable number of pages
pub requested: u16, // number of pages requested by program
pub provisioned: usize, // number of pages provisioned for use
pub pages: Vec<Page>, // all allocated pages
pub offset_1: u16,
pub address_1: u16,
pub offset_2: u16,
pub address_2: u16,
pub copy_length: u16,
}
impl MemoryDevice {
pub fn new() -> Self {
Self {
limit: u16::MAX,
requested: 0,
provisioned: 0,
pages: Vec::new(),
offset_1: 0,
address_1: 0,
offset_2: 0,
address_2: 0,
copy_length: 0,
}
}
fn_read_head! { read_head_1( offset_1, address_1) }
fn_read_head! { read_head_2( offset_2, address_2) }
fn_write_head!{ write_head_1(offset_1, address_1) }
fn_write_head!{ write_head_2(offset_2, address_2) }
pub fn provision(&mut self) {
self.provisioned = std::cmp::min(self.requested, self.limit) as usize;
// Defer allocation of new pages.
self.pages.truncate(self.provisioned as usize);
}
pub fn copy(&mut self) {
let src = self.offset_2 as usize;
let dest = self.offset_1 as usize;
let count = self.copy_length as usize;
// Pre-allocate destination pages as needed.
let pages_needed = std::cmp::min(dest + count, self.provisioned);
if pages_needed > self.pages.len() {
self.pages.resize(pages_needed, [0; 256]);
}
for i in 0..count {
let src_page = match self.pages.get(src + i) {
Some(src_page) => src_page.to_owned(),
None => [0; 256],
};
match self.pages.get_mut(dest + i) {
Some(dest) => *dest = src_page,
None => break,
};
}
}
}
impl Device for MemoryDevice {
fn read(&mut self, port: u8) -> u8 {
match port {
0x0 => self.read_head_1(),
0x1 => self.read_head_1(),
0x2 => read_h!(self.offset_1),
0x3 => read_l!(self.offset_1),
0x4 => read_h!(self.address_1),
0x5 => read_l!(self.address_1),
0x6 => read_h!(self.provisioned),
0x7 => read_l!(self.provisioned),
0x8 => self.read_head_2(),
0x9 => self.read_head_2(),
0xa => read_h!(self.offset_2),
0xb => read_l!(self.offset_2),
0xc => read_h!(self.address_2),
0xd => read_l!(self.address_2),
0xe => 0x00,
0xf => 0x00,
_ => unreachable!(),
}
}
fn write(&mut self, port: u8, value: u8) -> Option<Signal> {
match port {
0x0 => self.write_head_1(value),
0x1 => self.write_head_1(value),
0x2 => write_h!(self.offset_1, value),
0x3 => write_l!(self.offset_1, value),
0x4 => write_h!(self.address_1, value),
0x5 => write_l!(self.address_1, value),
0x6 => write_h!(self.requested, value),
0x7 => { write_l!(self.requested, value); self.provision(); },
0x8 => self.write_head_2(value),
0x9 => self.write_head_2(value),
0xa => write_h!(self.offset_2, value),
0xb => write_l!(self.offset_2, value),
0xc => write_h!(self.address_2, value),
0xd => write_l!(self.address_2, value),
0xe => write_h!(self.copy_length, value),
0xf => { write_l!(self.copy_length, value); self.copy(); },
_ => unreachable!(),
};
return None;
}
fn wake(&mut self) -> bool {
false
}
}
|
