Update devices to match new specifications

1 files changed, 89 insertions, 0 deletions

diff --git a/src/devices/memory.rs b/src/devices/memory.rs
new file mode 100644
index 0000000..1d33f64
--- /dev/null
+++ b/src/devices/memory.rs
@@ -0,0 +1,89 @@
+macro_rules! then_inc { ($v:expr) => {{ $v = $v.wrapping_add(1); $v as usize }}; }
+
+type Page = [u8; 65536];
+fn new_blank_page() -> [u8; 65536] { [0; 65536] }
+
+
+pub struct MemoryDevice {
+    pages: Vec<Page>,
+    pub page_limit: u16,
+    pub page_1: u16,
+    pub address_1: u16,
+    pub page_2: u16,
+    pub address_2: u16,
+    pub copy_length: u16,
+}
+
+impl MemoryDevice {
+    pub fn new() -> Self {
+        Self {
+            pages: Vec::new(),
+            page_limit: 0,
+            page_1: 0,
+            address_1: 0,
+            page_2: 0,
+            address_2: 0,
+            copy_length: 0,
+        }
+    }
+
+    pub fn page_count(&self) -> u16 {
+        self.pages.len() as u16
+    }
+
+    pub fn copy(&mut self) {
+        // Return if at least one page is out-of-bounds
+        if self.page_1 as usize >= self.pages.len()
+        || self.page_2 as usize >= self.pages.len() {
+            return
+        }
+        let p1 = self.page_1 as usize;
+        let p2 = self.page_2 as usize;
+        let a1 = self.address_1;
+        let a2 = self.address_2;
+
+        for i in 0..=self.copy_length {
+            let byte = self.pages[p2][a2.wrapping_add(i) as usize];
+            self.pages[p1][a1.wrapping_add(i) as usize] = byte;
+        }
+    }
+
+    pub fn expand_memory(&mut self) {
+        let size = std::cmp::max(self.page_1, self.page_2) as usize + 1;
+        if size < self.page_limit as usize {
+            self.pages.resize_with(size, new_blank_page);
+        }
+    }
+
+    pub fn read_from_head_1(&mut self) -> u8 {
+        let address = then_inc!(self.address_1);
+        if let Some(page) = self.pages.get(self.page_1 as usize) {
+            page[address]
+        } else {
+            0x00
+        }
+    }
+
+    pub fn read_from_head_2(&mut self) -> u8 {
+        let address = then_inc!(self.address_2);
+        if let Some(page) = self.pages.get(self.page_2 as usize) {
+            page[address]
+        } else {
+            0x00
+        }
+    }
+
+    pub fn write_to_head_1(&mut self, byte: u8) {
+        let address = then_inc!(self.address_1);
+        if let Some(page) = self.pages.get_mut(self.page_1 as usize) {
+            page[address] = byte;
+        }
+    }
+
+    pub fn write_to_head_2(&mut self, byte: u8) {
+        let address = then_inc!(self.address_2);
+        if let Some(page) = self.pages.get_mut(self.page_2 as usize) {
+            page[address] = byte;
+        }
+    }
+}