diff --git a/.cargo/config.toml b/.cargo/config.toml
new file mode 100644
index 0000000..f042f84
--- /dev/null
+++ b/.cargo/config.toml
@@ -0,0 +1 @@
+build.target-dir = "_build/native"
diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..2fd2d66
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "spicei"
+version = "0.1.0"
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..c7e96cd
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,3 @@
+[workspace]
+members = ["native"]
+resolver = "2"
diff --git a/native/Cargo.toml b/native/Cargo.toml
new file mode 100644
index 0000000..ed315d2
--- /dev/null
+++ b/native/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "spicei"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
diff --git a/native/src/lib.rs b/native/src/lib.rs
new file mode 100644
index 0000000..8189a4e
--- /dev/null
+++ b/native/src/lib.rs
@@ -0,0 +1 @@
+pub mod opcodes;
diff --git a/native/src/main.rs b/native/src/main.rs
new file mode 100644
index 0000000..b49dfb4
--- /dev/null
+++ b/native/src/main.rs
@@ -0,0 +1,2 @@
+
+fn main() {}
diff --git a/native/src/opcodes.rs b/native/src/opcodes.rs
new file mode 100644
index 0000000..ddbdb1d
--- /dev/null
+++ b/native/src/opcodes.rs
@@ -0,0 +1,166 @@
+use std::fmt;
+
+#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
+#[repr(transparent)]
+pub struct Reg(pub u16);
+
+impl fmt::Display for Reg {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "R{}", self.0)
+    }
+}
+
+#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash, Debug)]
+#[repr(transparent)]
+pub struct ConstIdx(pub u16);
+
+impl fmt::Display for ConstIdx {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "({})", self.0)
+    }
+}
+
+#[derive(Copy, Clone, Eq, PartialEq)]
+pub enum ArgV {
+    R(Reg),
+    K(ConstIdx),
+}
+
+impl fmt::Display for ArgV {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::R(r) => r.fmt(f),
+            Self::K(k) => k.fmt(f),
+        }
+    }
+}
+
+#[derive(Copy, Clone, Eq, PartialEq)]
+pub enum ArgL {
+    SubI(Reg, i16),
+    SubR(Reg, Reg),
+}
+
+impl fmt::Display for ArgL {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::SubI(r, l) => write!(f, "{r}[{l}]"),
+            Self::SubR(r, l) => write!(f, "{r}[{l}]"),
+        }
+    }
+}
+
+#[derive(Copy, Clone, Eq, PartialEq)]
+pub enum Ins {
+    O(InsO, i32),
+    V(InsV, ArgV),
+    RV(InsRV, Reg, ArgV),
+    RL(InsRL, Reg, ArgL),
+    LV(InsLV, ArgL, ArgV),
+    RRK(InsRRK, Reg, Reg, ConstIdx),
+}
+
+impl fmt::Display for Ins {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::O(InsO::JMP, o) => write!(f, "jmp {o:+}"),
+            Self::V(InsV::RET, v) => write!(f, "ret {v}"),
+            Self::V(InsV::BTR, v) => write!(f, "btr {v}"),
+            Self::RV(InsRV::Op(opr), r, v) => write!(f, "{opr} {r}, {v}"),
+            Self::RV(InsRV::Br(cmp), r, v) => write!(f, "b{cmp} {r}, {v}"),
+            Self::RL(InsRL::Get(opr), r, l) => write!(f, "{opr} {r}, {l}"),
+            Self::RL(InsRL::CAL(n), r, l) => write!(f, "cal {r}, {l}({r},...{n})"),
+            Self::RL(InsRL::RETCAL(n), r, l) => write!(f, "ret cal {l}({r},...{n})"),
+            Self::LV(InsLV::Set(opr), l, v) => write!(f, "{opr} {l}, {v}"),
+            Self::RRK(InsRRK::LOC, r, v, k) => write!(f, "loc {r}, {v}, {k}"),
+        }
+    }
+}
+
+#[derive(Copy, Clone, Eq, PartialEq)]
+pub enum InsV {
+    RET,
+    BTR,
+}
+
+#[derive(Copy, Clone, Eq, PartialEq)]
+pub enum InsRV {
+    Op(Opr),
+    Br(Cmp),
+}
+
+#[derive(Copy, Clone, Eq, PartialEq)]
+pub enum InsRL {
+    Get(Opr),
+    CAL(u16),
+    RETCAL(u16),
+}
+
+#[derive(Copy, Clone, Eq, PartialEq)]
+pub enum InsLV {
+    Set(Opr),
+}
+
+#[derive(Copy, Clone, Eq, PartialEq)]
+pub enum InsRRK {
+    LOC,
+}
+
+#[derive(Copy, Clone, Eq, PartialEq)]
+pub enum InsO {
+    JMP,
+}
+
+#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash, Debug)]
+pub enum Opr {
+    MOV,
+    CON,
+    NOT,
+    NEG,
+    ADD,
+    SUB,
+    MUL,
+    DIV,
+    MOD,
+    Cmp(Cmp),
+}
+
+impl fmt::Display for Opr {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::MOV => write!(f, "mov"),
+            Self::CON => write!(f, "con"),
+            Self::NOT => write!(f, "not"),
+            Self::NEG => write!(f, "neg"),
+            Self::ADD => write!(f, "add"),
+            Self::SUB => write!(f, "sub"),
+            Self::MUL => write!(f, "mul"),
+            Self::DIV => write!(f, "div"),
+            Self::MOD => write!(f, "mod"),
+            Self::Cmp(cmp) => write!(f, "c{cmp}"),
+        }
+    }
+}
+
+#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash, Debug)]
+pub enum Cmp {
+    EQ,
+    NE,
+    LT,
+    GT,
+    LE,
+    GE,
+}
+
+impl fmt::Display for Cmp {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::EQ => write!(f, "eq"),
+            Self::NE => write!(f, "ne"),
+            Self::LT => write!(f, "lt"),
+            Self::GT => write!(f, "gt"),
+            Self::LE => write!(f, "le"),
+            Self::GE => write!(f, "ge"),
+        }
+    }
+}