From 483e149b32419d26af55a7359b7f24dcaa03d3b6 Mon Sep 17 00:00:00 2001
From: Rekai Musuka <rekai@musuka.dev>
Date: Mon, 17 Jan 2022 14:19:40 -0400
Subject: [PATCH] feat(cpu): implement RRX for Barrel Shifter

---
 src/cpu/arm/barrel_shifter.zig | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/cpu/arm/barrel_shifter.zig b/src/cpu/arm/barrel_shifter.zig
index a7f28d4..b1827f1 100644
--- a/src/cpu/arm/barrel_shifter.zig
+++ b/src/cpu/arm/barrel_shifter.zig
@@ -91,3 +91,12 @@ pub fn rotateRight(comptime S: bool, cpsr: *CPSR, rm: u32, amount: u8) u32 {
 
     return result;
 }
+
+pub fn rotateRightExtended(comptime S: bool, cpsr: *CPSR, rm: u32) u32 {
+    if (!S) std.debug.panic("[BarrelShifter] Turns out I don't know how RRX works", .{});
+
+    const carry: u32 = @boolToInt(cpsr.c.read());
+    cpsr.c.write(rm & 1 == 1);
+
+    return (carry << 31) | (rm >> 1);
+}