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diff --git a/src/arm32/instruction_codec/mod.rs b/src/arm32/instruction_codec/mod.rs
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+// Copyright 2024 Gabriel Bjørnager Jensen.
+//
+// This file is part of Pollex.
+//
+// Pollex is free software: you can redistribute it
+// and/or modify it under the terms of the GNU Af-
+// fero General Public License as published by the
+// Free Software Foundation, either version 3 of
+// the License, or (at your option) any later ver-
+// sion.
+//
+// Pollex is distributed in the hope that it will
+// be useful, but WITHOUT ANY WARRANTY; without
+// even the implied warranty of MERCHANTABILITY or
+// FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Af-
+// fero General Public License along with Pollex.
+// If not, see <https://www.gnu.org/licenses/>.
+
+#[cfg(test)]
+mod test;
+
+mod encode_arm;
+
+use core::num::Wrapping;
+
+/// Codec for encoding and decoding instruction.
+///
+/// Arm instructions can be encoded/decoded using the [`encode_arm`](InstructionCodec::encode_arm) and `decode_arm` (soon).
+/// Thumb instruction will similarly be manipulated using `encode_thumb` and `decode_thumb`.
+///
+/// This structure keeps track of the adress at which instructions are to be placed (see *Rationale*).
+/// If encoding causes this internal address to go past `0xFFFFFFFF`, the value is safely wrapped to the origin (i.e. `0x00000000`).
+///
+/// # Rationale
+///
+/// This structure is useful for the few functions that encode differently according to their position.
+///
+/// For example `B 0x08000000` encodes the immediate (in this case `0x08000000`) as an offset from `PC`.
+/// This is despite taking an address as its operand in assembly.
+#[derive(Clone, Debug)]
+pub struct InstructionCodec {
+ address: Wrapping<u32>,
+}
+
+impl InstructionCodec {
+ /// Constructs a new codec with a given starting address.
+ #[inline(always)]
+ #[must_use]
+ pub const fn new_at(address: u32) -> Self {
+ Self { address: Wrapping(address) }
+ }
+}
+
+impl Default for InstructionCodec {
+ #[inline(always)]
+ fn default() -> Self { Self::new_at(0x00000000) }
+}