[dsp] Fix display instruction

README.md

@@ -13,14 +13,15 @@ Chip 8 emulator/interpreter.
 - [X] Registers
 - [X] Stack
 - [X] Display
-- [ ] Instruction Processing
+- [X] Instruction Processing
   - [X] Bare requirements for IBM Logo
-  - [ ] ALU operations
+  - [X] ALU operations
-  - [ ] Procedure related
+  - [X] Procedure related
-  - [ ] Timer
+  - [X] Timer
-  - [ ] Super chip8 compatibility.
+  - [X] Super chip8 compatibility.
-- [ ] Audio
+- [X] Audio
-- [ ] Keyboard
+  - Audio seems to be broken on my device. I will check with other devices.
+- [X] Keyboard
 
 ### More information on CHIP-8
 

src/device/device.rs

@@ -290,10 +290,14 @@ impl Device {
         for i in 0..n as usize {
             let index = Self::get_framebuffer_index(x, y + i);
             let slice_from_memory = self.memory[self.registers.i as usize + i];
-
+            // if we are drawing below the screen
+            if (y+i)>=Self::FRAME_BUFFER_HEIGHT {
+                log::trace!("Overdraw detected, skipping");
+                continue;
+            }
             for bit_index in (0..8).rev() {
-                // if i'm going to the next line, stop
+                // if going out of the screen, stop
-                if Self::get_framebuffer_index(0, y + 1) == index {
+                if Self::get_framebuffer_index(0, y+i + 1) <= (index + (7 - bit_index)) {
                     break;
                 }
                 let bit_is_true = (slice_from_memory & (1 << bit_index)) == (1 << bit_index);