diff --git a/Cargo.lock b/Cargo.lock
index 6abd02e..080efbe 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -8,6 +8,14 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
 
+[[package]]
+name = "bits"
+version = "0.1.0"
+dependencies = [
+ "quote",
+ "syn 2.0.18",
+]
+
 [[package]]
 name = "modular-bitfield"
 version = "0.11.2"
@@ -26,7 +34,7 @@ checksum = "5a7d5f7076603ebc68de2dc6a650ec331a062a13abaa346975be747bbfa4b789"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 1.0.109",
 ]
 
 [[package]]
@@ -107,18 +115,18 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.58"
+version = "1.0.60"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fa1fb82fc0c281dd9671101b66b771ebbe1eaf967b96ac8740dcba4b70005ca8"
+checksum = "dec2b086b7a862cf4de201096214fa870344cf922b2b30c167badb3af3195406"
 dependencies = [
  "unicode-ident",
 ]
 
 [[package]]
 name = "quote"
-version = "1.0.27"
+version = "1.0.28"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8f4f29d145265ec1c483c7c654450edde0bfe043d3938d6972630663356d9500"
+checksum = "1b9ab9c7eadfd8df19006f1cf1a4aed13540ed5cbc047010ece5826e10825488"
 dependencies = [
  "proc-macro2",
 ]
@@ -127,6 +135,7 @@ dependencies = [
 name = "riscy-rust"
 version = "0.1.0"
 dependencies = [
+ "bits",
  "modular-bitfield",
  "num",
 ]
@@ -148,6 +157,17 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "syn"
+version = "2.0.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "32d41677bcbe24c20c52e7c70b0d8db04134c5d1066bf98662e2871ad200ea3e"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.8"
diff --git a/Cargo.toml b/Cargo.toml
index 819cea7..09e0ce4 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -3,6 +3,9 @@ name = "riscy-rust"
 version = "0.1.0"
 edition = "2021"
 
+[dependencies.bits]
+path = "lib/bits"
+
 [dependencies]
 modular-bitfield = "0.11.2"
 num = "0.4.0"
diff --git a/lib/bits/Cargo.toml b/lib/bits/Cargo.toml
new file mode 100644
index 0000000..f2e8f73
--- /dev/null
+++ b/lib/bits/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "bits"
+version = "0.1.0"
+edition = "2021"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+quote = "1.0.28"
+syn = {version ="2.0.18", features = ["full"]}
diff --git a/lib/bits/src/lib.rs b/lib/bits/src/lib.rs
new file mode 100644
index 0000000..e7d209b
--- /dev/null
+++ b/lib/bits/src/lib.rs
@@ -0,0 +1,53 @@
+use proc_macro::TokenStream;
+use quote::quote;
+use syn::{Expr, LitStr, Token};
+
+struct ParsedInput {
+    expression: Expr,
+    _comma: Token![,],
+    token_string: LitStr,
+}
+
+fn parse_input(input: syn::parse::ParseStream) -> syn::Result<ParsedInput> {
+    Ok(ParsedInput {
+        expression: input.parse()?,
+        _comma: input.parse()?,
+        token_string: input.parse()?,
+    })
+}
+
+#[proc_macro]
+pub fn match_mask(input: TokenStream) -> TokenStream {
+    let parsed =
+        syn::parse::Parser::parse(parse_input, input).unwrap();
+
+    let input = parsed.expression;
+
+    let tokens: String = parsed
+        .token_string
+        .value()
+        .parse()
+        .expect("Failed to parse token string");
+
+    let mut ones: u32 = 0;
+    let mut zeros: u32 = 0;
+
+    for (idx, bit) in tokens.chars().rev().enumerate() {
+        match bit {
+            '1' => {
+                ones |= 1 << idx;
+                zeros |= 1 << idx;
+            }
+            '0' => {
+                zeros |= 1 << idx;
+            }
+            _ => continue,
+        }
+    }
+
+    let expanded = quote! {
+        #input & #zeros ^ #ones == 0
+    };
+
+    TokenStream::from(expanded)
+}
diff --git a/src/ext/decode.rs b/src/ext/decode.rs
index 7b262f7..221aed2 100644
--- a/src/ext/decode.rs
+++ b/src/ext/decode.rs
@@ -1,36 +1,35 @@
+use bits::match_mask;
+
 use crate::system::rv32;
 use crate::cpu;
 
-macro_rules! match_mask {
-    ($int:expr, $($bit:expr)+) => { 'scope: {
-        let mut int = $int;
-
-        $({
-            let msb = int & (1 << 31);
-            let bit = $bit;
-            if (bit == 0 || bit == 1) && bit != msb.reverse_bits() {
-                break 'scope false;
-            }
-            int <<= 1;
-        })+
-
-        true
-    }};
-}
-
 trait Instruction {
-    fn get_mask() -> rv32::Word;
+    fn match_inst(inst: rv32::Word) -> bool;
     fn step(&self, inst: rv32::Word, state: &mut cpu::CPU);
 }
 
-struct ADDI {}
+struct ADDI;
 impl Instruction for ADDI  {
-    fn get_mask() -> rv32::Word {
+    fn match_inst(inst: rv32::Word) -> bool {
+        match_mask!(inst, "xxxxxxxxxxxxxxxxxx000xxxx0010011")
+    }
+
+    fn step(&self, inst: rv32::Word, state: &mut cpu::CPU) {
     }
 }
 
-pub fn decode_inst(inst: rv32::WORD) -> fn() {
-    // loop over all bitmasks
-    // 
 
+#[derive(Clone, Copy)]
+enum I {
+    ADDI(ADDI),
+}
+
+#[derive(Clone, Copy)]
+enum Extensions {
+    I,
+}
+
+pub fn decode_inst(inst: rv32::Word) -> fn() {
+    // we need to go over every instruction and see if it matches
+    // we can do smarter things with cacheing later - this aint blazin
 }
diff --git a/src/main.rs b/src/main.rs
index 3c3df4a..53a63fb 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -66,7 +66,7 @@ fn main() {
     println!("VM Starting Up");
 
     let mut vm = VMRV32I::new();
-    vm.load_prog("./test/test.bin");
+    vm.load_prog("./test/add.bin");
     vm.dump_prog();
     vm.dispatch();
 }