From df8acbfa3271dc0dd85b73210ca7a57995684379 Mon Sep 17 00:00:00 2001
From: Alex Janka <alex@alexjanka.com>
Date: Wed, 18 Jan 2023 13:14:22 +1100
Subject: [PATCH] rotate instructions

---
 src/processor.rs | 67 +++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 63 insertions(+), 4 deletions(-)

diff --git a/src/processor.rs b/src/processor.rs
index 3f9c1e5..09ba232 100644
--- a/src/processor.rs
+++ b/src/processor.rs
@@ -13,6 +13,11 @@ enum FLAGS {
     C = 4,
 }
 
+enum Direction {
+    Left,
+    Right,
+}
+
 pub struct CPU {
     pub memory: Memory,
     pub state: State,
@@ -43,7 +48,9 @@ impl CPU {
                 self.state.bc.as_u8s.left = self.sub_u8s(self.state.bc.as_u8s.left, 1)
             },
             0x06 => self.state.bc.as_u8s.left = self.ld_immediate_byte(),
-            0x07 => panic!("RCLA rotate instruction: 0x07"),
+            0x07 => unsafe {
+                self.state.af.as_u8s.left = self.rlc(self.state.af.as_u8s.left, Direction::Left)
+            },
             0x08 => unsafe {
                 let address = self.ld_immediate_word().as_u16;
                 let word = self.state.sp;
@@ -61,7 +68,9 @@ impl CPU {
                 self.state.bc.as_u8s.right = self.sub_u8s(self.state.bc.as_u8s.right, 0x1)
             },
             0x0E => self.state.bc.as_u8s.right = self.ld_immediate_byte(),
-            0x0F => panic!("RRCA rotate instruction: 0x0F"),
+            0x0F => unsafe {
+                self.state.af.as_u8s.left = self.rlc(self.state.af.as_u8s.left, Direction::Right)
+            },
             0x10 => panic!("STOP instruction"),
             0x11 => self.state.de = self.ld_immediate_word(),
             0x12 => unsafe {
@@ -77,7 +86,9 @@ impl CPU {
                 self.state.de.as_u8s.left = self.sub_u8s(self.state.de.as_u8s.left, 0x1)
             },
             0x16 => self.state.de.as_u8s.left = self.ld_immediate_byte(),
-            0x17 => panic!("RLA rotate instruction: 0x17"),
+            0x17 => unsafe {
+                self.state.af.as_u8s.left = self.rl(self.state.af.as_u8s.left, Direction::Left);
+            },
             0x18 => unsafe {
                 let t = (as_signed(self.ld_immediate_byte()) as i16) as u16;
                 self.state.pc.as_u16 = self.add_u16s(self.state.pc.as_u16, t)
@@ -97,7 +108,9 @@ impl CPU {
                 self.state.de.as_u8s.right = self.sub_u8s(self.state.de.as_u8s.right, 1)
             },
             0x1E => self.state.de.as_u8s.right = self.ld_immediate_byte(),
-            0x1F => panic!("RRA rotate instruction: 0x1F"),
+            0x1F => unsafe {
+                self.state.af.as_u8s.left = self.rl(self.state.af.as_u8s.left, Direction::Right);
+            },
             0x20 => {
                 let jump_size = self.ld_immediate_byte();
                 if self.get_flag(FLAGS::Z) == 0 {
@@ -846,6 +859,9 @@ impl CPU {
 
     fn cb_subop(&mut self, subop: u8) {
         match subop {
+            0x11 => unsafe {
+                self.state.bc.as_u8s.right = self.rl(self.state.bc.as_u8s.right, Direction::Left)
+            },
             0x7C => unsafe {
                 self.set_or_clear_flag(FLAGS::Z, !get_bit(self.state.hl.as_u8s.left, 7))
             },
@@ -861,6 +877,27 @@ impl CPU {
         };
     }
 
+    fn rlc(&mut self, byte: u8, direction: Direction) -> u8 {
+        let (mut rotated, carry) = rotate(byte, &direction);
+        if carry {
+            rotated += get_rotation_carry(&direction);
+            self.set_flag(FLAGS::C);
+        }
+        return rotated;
+    }
+
+    fn rl(&mut self, byte: u8, direction: Direction) -> u8 {
+        let old_carry = self.get_flag(FLAGS::C);
+        let (mut rotated, carry) = rotate(byte, &direction);
+        if old_carry > 0 {
+            rotated += get_rotation_carry(&direction);
+        }
+        if carry {
+            self.set_flag(FLAGS::C);
+        }
+        return rotated;
+    }
+
     fn rst(&mut self, address: u16) {
         self.push(self.state.pc);
         self.state.pc.as_u8s.left = 0x0;
@@ -1003,3 +1040,25 @@ fn get_bit(byte: u8, flag: u8) -> bool {
     let got = byte & mask;
     return got > 0x0;
 }
+
+fn rotate(byte: u8, direction: &Direction) -> (u8, bool) {
+    match direction {
+        Direction::Left => {
+            let carry = get_bit(byte, 7);
+            let r = byte << 1;
+            return (r, carry);
+        }
+        Direction::Right => {
+            let carry = get_bit(byte, 0);
+            let r = byte >> 1;
+            return (r, carry);
+        }
+    }
+}
+
+fn get_rotation_carry(direction: &Direction) -> u8 {
+    match direction {
+        Direction::Left => 0b1,
+        Direction::Right => 0b10000000,
+    }
+}