feat: new secure feature

Cargo.toml

@@ -17,6 +17,7 @@ crate-type = ["cdylib", "rlib"]
 [features]
 wasm = ["wasm-bindgen"]
 debug = []
+secure = []
 cpulog = []
 gen-mock = []
 

frontends/sdl/Cargo.toml

@@ -10,6 +10,7 @@ edition = "2018"
 [features]
 slow = []
 debug = ["boytacean/debug"]
+secure = ["boytacean/secure"]
 cpulog = ["boytacean/cpulog"]
 
 [dependencies.boytacean]

frontends/sdl/README.md

@@ -32,8 +32,9 @@ cargo run --features debug
 
 ## Features
 
-| Provider | Description                                                                 |
-| -------- | --------------------------------------------------------------------------- |
-| `debug`  | Activates the base `debug` feature from Boytacean.                          |
-| `slow`   | Runs the emulator at a very slow page 60x slower to allow visual debugging. |
-| `cpulog` | Prints a log of the CPU instruction executed.                               |
+| Provider | Description                                                                                       |
+| -------- | ------------------------------------------------------------------------------------------------- |
+| `debug`  | Activates the base `debug` feature from Boytacean.                                                |
+| `secure` | Additional safety instructions are executed to make sure the machine does no run "out of tracks". |
+| `slow`   | Runs the emulator at a very slow page 60x slower to allow visual debugging.                       |
+| `cpulog` | Prints a log of the CPU instruction executed.                                                     |

src/cpu.rs

@@ -280,7 +280,12 @@ impl Cpu {
         }
 
         #[cfg(feature = "cpulog")]
-        println!("[0x{:04x}] {}", self.pc - 1, inst_str);
+        println!("[0x{:04x}] {}\t({} cycles)", self.pc - 1, inst_str, inst_time);
+
+        #[cfg(feature = "secure")]
+        if self.mmu.boot_active() && self.pc - 1 > 0x08ff {
+            panic!("Invalid boot address: {:04x}", self.pc - 1);
+        }
 
         // calls the current instruction and increments the number of
         // cycles executed by the instruction time of the instruction