Restructure the library

The main type of the library is now the BedrockEmulator type, which
contains a new BedrockCore type and an instance of a user-implemented
DeviceBus trait.

This new structure makes it possible to hot-swap a device bus while
a BedrockEmulator is running, which keeps the core and the device bus
well separated. This was important when bedrock-pc was going to have
two graphical emulator types and upgrade from one to the other once
the screen device was accessed.

The new structure also vastly simplifies the code previously required
with the old Bedrock type, which was parametric over 16 device types
and so needed each device type to be enumerated in every place the
Bedrock type was stored. The new BedrockEmulator type is only
parametric over the particular DeviceBus implementation.

1 files changed, 4 insertions, 67 deletions

diff --git a/src/device_bus.rs b/src/device_bus.rs
index aaa0717..6a04f66 100644
--- a/src/device_bus.rs
+++ b/src/device_bus.rs
@@ -1,6 +1,5 @@
 use crate::*;
 
-
 pub trait Device {
     fn read(&mut self, port: u8) -> u8;
     fn write(&mut self, port: u8, value: u8) -> Option<Signal>;
@@ -13,70 +12,8 @@ impl Device for () {
     fn wake(&mut self) -> bool { false }
 }
 
-
-pub struct DeviceBus<D0,D1,D2,D3,D4,D5,D6,D7,D8,D9,DA,DB,DC,DD,DE,DF> {
-    pub dev_0: D0,
-    pub dev_1: D1,
-    pub dev_2: D2,
-    pub dev_3: D3,
-    pub dev_4: D4,
-    pub dev_5: D5,
-    pub dev_6: D6,
-    pub dev_7: D7,
-    pub dev_8: D8,
-    pub dev_9: D9,
-    pub dev_a: DA,
-    pub dev_b: DB,
-    pub dev_c: DC,
-    pub dev_d: DD,
-    pub dev_e: DE,
-    pub dev_f: DF,
-}
-
-impl<D0:Device, D1:Device, D2:Device, D3:Device, D4:Device, D5:Device, D6:Device, D7:Device,
-     D8:Device, D9:Device, DA:Device, DB:Device, DC:Device, DD:Device, DE:Device, DF:Device>
-DeviceBus<D0,D1,D2,D3,D4,D5,D6,D7,D8,D9,DA,DB,DC,DD,DE,DF> {
-    pub fn read_u8(&mut self, port: u8) -> u8 {
-        match port & 0xf0 {
-            0x00 => self.dev_0.read(port & 0x0f),
-            0x10 => self.dev_1.read(port & 0x0f),
-            0x20 => self.dev_2.read(port & 0x0f),
-            0x30 => self.dev_3.read(port & 0x0f),
-            0x40 => self.dev_4.read(port & 0x0f),
-            0x50 => self.dev_5.read(port & 0x0f),
-            0x60 => self.dev_6.read(port & 0x0f),
-            0x70 => self.dev_7.read(port & 0x0f),
-            0x80 => self.dev_8.read(port & 0x0f),
-            0x90 => self.dev_9.read(port & 0x0f),
-            0xA0 => self.dev_a.read(port & 0x0f),
-            0xB0 => self.dev_b.read(port & 0x0f),
-            0xC0 => self.dev_c.read(port & 0x0f),
-            0xD0 => self.dev_d.read(port & 0x0f),
-            0xE0 => self.dev_e.read(port & 0x0f),
-            0xF0 => self.dev_f.read(port & 0x0f),
-            _ => unreachable!(),
-        }
-    }
-
-    pub fn write_u8(&mut self, port: u8, value: u8) -> Option<Signal> {
-        match port & 0xf0 {
-            0x00 => self.dev_0.write(port & 0x0f, value),
-            0x10 => self.dev_1.write(port & 0x0f, value),
-            0x20 => self.dev_2.write(port & 0x0f, value),
-            0x30 => self.dev_3.write(port & 0x0f, value),
-            0x40 => self.dev_4.write(port & 0x0f, value),
-            0x50 => self.dev_5.write(port & 0x0f, value),
-            0x60 => self.dev_6.write(port & 0x0f, value),
-            0x70 => self.dev_7.write(port & 0x0f, value),
-            0x80 => self.dev_8.write(port & 0x0f, value),
-            0x90 => self.dev_9.write(port & 0x0f, value),
-            0xA0 => self.dev_a.write(port & 0x0f, value),
-            0xB0 => self.dev_b.write(port & 0x0f, value),
-            0xC0 => self.dev_c.write(port & 0x0f, value),
-            0xD0 => self.dev_d.write(port & 0x0f, value),
-            0xE0 => self.dev_e.write(port & 0x0f, value),
-            0xF0 => self.dev_f.write(port & 0x0f, value),
-            _ => unreachable!(),
-        }
-    }
+pub trait DeviceBus {
+    fn read(&mut self, port: u8) -> u8;
+    fn write(&mut self, port: u8, value: u8) -> Option<Signal>;
+    fn wake(&mut self) -> bool;
 }