Rewrite emulatorv1.0.0-alpha1

This is a complete rewrite and restructure of the entire emulator
project, as part of the effort in locking down the Bedrock specification
and in creating much better tooling for creating and using Bedrock
programs.

This commit adds a command-line argument scheme, an embedded assembler,
a headless emulator for use in non-graphical environments, deferred
window creation for programs that do not access the screen device,
and new versions of phosphor and bedrock-core. The new version of
phosphor supports multi-window programs, which will make it possible to
implement program forking in the system device later on, and the new
version of bedrock-core implements the final core specification.

1 files changed, 152 insertions, 0 deletions

diff --git a/src/devices/memory_device.rs b/src/devices/memory_device.rs
new file mode 100644
index 0000000..7c1aeda
--- /dev/null
+++ b/src/devices/memory_device.rs
@@ -0,0 +1,152 @@
+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: 0,
+            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
+    }
+}