From a9d252f758c3978e20cf45c87be63e9b18d66062 Mon Sep 17 00:00:00 2001
From: Denis Nutiu <denis.nutiu@gmail.com>
Date: Tue, 10 Dec 2024 19:05:20 +0200
Subject: [PATCH] c-like struct for Draw instruction

---
 src/emulator.rs    | 12 +++++-------
 src/instruction.rs | 18 +++++++++++-------
 2 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/src/emulator.rs b/src/emulator.rs
index 8a4e414..f245946 100644
--- a/src/emulator.rs
+++ b/src/emulator.rs
@@ -221,18 +221,16 @@ where
                 trace!("Set index register to data {:04x}", data);
                 self.index_register = data;
             }
-            ProcessorInstruction::Draw(vx_register, vy_register, num_rows) => {
-                trace!(
-                    "Draw vx_register={vx_register} vy_register={vy_register} pixels={num_rows}"
-                );
-                let x_coordinate = self.registers[vx_register as usize];
-                let y_coordinate = self.registers[vy_register as usize];
+            ProcessorInstruction::Draw { vx, vy, rows } => {
+                trace!("Draw vx_register={vx} vy_register={vy} pixels={rows}");
+                let x_coordinate = self.registers[vx as usize];
+                let y_coordinate = self.registers[vy as usize];
 
                 // Keep track if any pixels were flipped
                 let mut flipped = false;
 
                 // Iterate over each row of our sprite
-                for y_line in 0..num_rows {
+                for y_line in 0..rows {
                     // Determine which memory address our row's data is stored
                     let addr = self.index_register + y_line as u16;
                     let pixels = self.memory[addr as usize];
diff --git a/src/instruction.rs b/src/instruction.rs
index b59b041..6ece8eb 100644
--- a/src/instruction.rs
+++ b/src/instruction.rs
@@ -25,7 +25,7 @@ pub enum ProcessorInstruction {
     /// Sets the index register
     SetIndexRegister { data: u16 },
     /// Draws to the screen.
-    Draw(u8, u8, u8),
+    Draw { vx: u8, vy: u8, rows: u8 },
     /// Call sets PC to the address and saves the return address on the stack
     Call(u16),
     /// Pops the stack and sets the PC
@@ -152,11 +152,11 @@ impl Instruction {
             // Draw on screen
             (0xD, _, _, _) => {
                 // DXYN
-                ProcessorInstruction::Draw(
-                    Self::grab_first_nibble(data),
-                    Self::grab_middle_nibble(data),
-                    Self::grab_last_nibble(data),
-                )
+                ProcessorInstruction::Draw {
+                    vx: Self::grab_first_nibble(data),
+                    vy: Self::grab_middle_nibble(data),
+                    rows: Self::grab_last_nibble(data),
+                }
             }
             (0x0, 0x0, 0xE, 0xE) => ProcessorInstruction::Return,
             (0x2, _, _, _) => ProcessorInstruction::Call(Self::grab_inner_data(data)),
@@ -529,7 +529,11 @@ mod tests {
         let instruction = Instruction::new([0xDA, 0xBC]);
         assert_eq!(
             instruction.processor_instruction,
-            ProcessorInstruction::Draw(0xA, 0xB, 0xC)
+            ProcessorInstruction::Draw {
+                vx: 0xA,
+                vy: 0xB,
+                rows: 0xC
+            }
         )
     }