From 6447db5df7b0d2d8fbac39acd25c3f2eb485a9a3 Mon Sep 17 00:00:00 2001
From: Nick Krichevsky <nick@ollien.com>
Date: Wed, 6 Dec 2023 15:44:56 -0500
Subject: [PATCH] Refactor bit manipulation HL instructions

---
 src/cpu/run/manip.rs | 73 +++++++++++++++++++++++---------------------
 1 file changed, 38 insertions(+), 35 deletions(-)

diff --git a/src/cpu/run/manip.rs b/src/cpu/run/manip.rs
index 9af119d..16a2ed3 100644
--- a/src/cpu/run/manip.rs
+++ b/src/cpu/run/manip.rs
@@ -20,41 +20,7 @@ impl Run for BitManipulationInstruction {
             }
 
             BitManipulationInstruction::SetHLValueBit { bit } => {
-                // TODO: wow this code kinda sucks, I kinda wanna make a better to deal with the HL values
-
-                let hl_addr = processor
-                    .registers
-                    .get_combined_register(register::Combined::HL);
-
-                #[allow(clippy::match_wildcard_for_single_variants)]
-                let hl_value = processor
-                    .memory
-                    .get(hl_addr.into())
-                    .map_err(|err| match err {
-                        memory::Error::GetInvalidAddress(addr) => {
-                            run::Error::InvalidRegisterAddress(
-                                register::SixteenBit::Combined(register::Combined::HL),
-                                addr,
-                            )
-                        }
-                        err => run::Error::Unknown(Box::new(err)),
-                    })?;
-
-                let upd_value = set_nth_bit(hl_value, bit);
-
-                #[allow(clippy::match_wildcard_for_single_variants)]
-                processor
-                    .memory
-                    .set(hl_addr.into(), upd_value)
-                    .map_err(|err| match err {
-                        memory::Error::SetInvalidAddress(addr, _value) => {
-                            run::Error::InvalidRegisterAddress(
-                                register::SixteenBit::Combined(register::Combined::HL),
-                                addr,
-                            )
-                        }
-                        err => run::Error::Unknown(Box::new(err)),
-                    })?;
+                transform_hl_value(processor, |value| set_nth_bit(value, bit))?;
 
                 Ok(Cycles(16))
             }
@@ -67,3 +33,40 @@ fn set_nth_bit(value: u8, bit: u8) -> u8 {
 
     value | (0x1 << bit)
 }
+
+fn transform_hl_value<F: Fn(u8) -> u8>(
+    processor: &mut Processor,
+    transform: F,
+) -> Result<(), run::Error> {
+    let hl_addr = processor
+        .registers
+        .get_combined_register(register::Combined::HL);
+
+    #[allow(clippy::match_wildcard_for_single_variants)]
+    let hl_value = processor
+        .memory
+        .get(hl_addr.into())
+        .map_err(|err| match err {
+            memory::Error::GetInvalidAddress(addr) => run::Error::InvalidRegisterAddress(
+                register::SixteenBit::Combined(register::Combined::HL),
+                addr,
+            ),
+            err => run::Error::Unknown(Box::new(err)),
+        })?;
+
+    let upd_value = transform(hl_value);
+
+    #[allow(clippy::match_wildcard_for_single_variants)]
+    processor
+        .memory
+        .set(hl_addr.into(), upd_value)
+        .map_err(|err| match err {
+            memory::Error::SetInvalidAddress(addr, _value) => run::Error::InvalidRegisterAddress(
+                register::SixteenBit::Combined(register::Combined::HL),
+                addr,
+            ),
+            err => run::Error::Unknown(Box::new(err)),
+        })?;
+
+    Ok(())
+}