Refactor command execution into commands module

This patch refactors the command execution.  A command is represented by
a struct implementing the Command trait.  The enum_cmd macro is used to
generate a mapping from the CommandId enum to a Command instance and to
execute the command.  The request and response data is manually
converted from and to raw byte slices.

As we do not have a standard library, we cannot create a Box<Command>
from a CommandId.  Instead, we directly delegate the execute method to
the corresponding Command.

1 files changed, 29 insertions, 0 deletions

diff --git a/src/util.rs b/src/util.rs
index 4fc4448..9325e9e 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -3,6 +3,35 @@
 
 use core::marker::Sized;
 
+macro_rules! enum_cmd {
+    (
+        $(#[$outer:meta])*
+        pub enum $name:ident {
+            $($var:ident($cmd:ident) = $num:expr),+
+            $(,)*
+        }
+    ) => {
+        enum_u8! {
+            $(#[$outer])*
+            pub enum $name {
+                $(
+                    $var = $num,
+                )*
+            }
+        }
+
+        impl $name {
+            pub fn execute(&self, data: &[u8], buf: &mut [u8]) -> CommandStatus {
+                match *self {
+                    $(
+                        $name::$var => $cmd::execute_raw(data, buf),
+                    )*
+                }
+            }
+        }
+    };
+}
+
 macro_rules! enum_u8 {
     (
         $(#[$outer:meta])*