1 files changed, 126 insertions, 0 deletions
diff --git a/src/debug.rs b/src/debug.rs
new file mode 100644
index 0000000..b007d9f
--- /dev/null
+++ b/src/debug.rs
@@ -0,0 +1,126 @@
+use crate::*;
+
+use inked::{ink, InkedString};
+
+
+pub struct DebugState {
+    pub enabled: bool,
+    last_cycle: usize,
+    mark: Instant,
+    symbols: DebugSymbols,
+}
+
+impl DebugState {
+    pub fn new<P: AsRef<Path>>(enabled: bool, symbols_path: Option<P>) -> Self {
+        Self {
+            enabled,
+            last_cycle: 0,
+            mark: Instant::now(),
+            symbols: DebugSymbols::from_path(symbols_path),
+        }
+    }
+
+    pub fn debug_full(&mut self, core: &BedrockCore) {
+        if self.enabled {
+            let prev_pc = core.mem.pc.wrapping_sub(1);
+            let cycle = core.cycle;
+            let delta = core.cycle.saturating_sub(self.last_cycle);
+            let elapsed = self.mark.elapsed();
+
+            eprintln!(" PC: 0x{prev_pc:04x}    Cycle: {cycle} (+{delta} in {elapsed:.2?})");
+            eprint!("WST: "); debug_stack(&core.wst);
+            eprint!("RST: "); debug_stack(&core.rst);
+            // Print information about the nearest symbol.
+            if let Some(symbol) = self.symbols.for_address(prev_pc) {
+                let name = &symbol.name;
+                let address = &symbol.address;
+                let mut string = InkedString::new();
+                string.push(ink!("SYM: "));
+                string.push(ink!("@{name}").blue());
+                string.push(ink!(" 0x{address:04X}"));
+                if let Some(location) = &symbol.location {
+                    string.push(ink!(" "));
+                    string.push(ink!("{location}").dim());
+                }
+                string.eprintln();
+            }
+        }
+        self.last_cycle = core.cycle;
+        self.mark = Instant::now();
+    }
+
+    pub fn debug_timing(&mut self, core: &BedrockCore) {
+        if self.enabled {
+            let cycle = core.cycle;
+            let delta = core.cycle.saturating_sub(self.last_cycle);
+            let elapsed = self.mark.elapsed();
+
+            eprintln!("Cycle: {cycle} (+{delta} in {elapsed:.2?})");
+        }
+        self.last_cycle = core.cycle;
+        self.mark = Instant::now();
+    }
+}
+
+
+fn debug_stack(stack: &Stack) {
+    for i in 0..(stack.sp as usize) {
+        eprint!("{:02X} ", stack.mem[i]);
+    }
+    eprintln!();
+}
+
+
+
+pub struct DebugSymbols {
+    pub symbols: Vec<DebugSymbol>
+}
+
+impl DebugSymbols {
+    /// Load debug symbols from a symbols file.
+    pub fn from_path<P: AsRef<Path>>(path: Option<P>) -> Self {
+        let mut symbols = Vec::new();
+        if let Some(path) = path {
+            if let Ok(string) = std::fs::read_to_string(path) {
+                for line in string.lines() {
+                    if let Some(symbol) = DebugSymbol::from_line(line) {
+                        symbols.push(symbol);
+                    }
+                }
+            }
+        }
+        symbols.sort_by_key(|s| s.address);
+        Self { symbols }
+    }
+
+    /// Return the symbol matching a given program address.
+    pub fn for_address(&self, address: u16) -> Option<&DebugSymbol> {
+        if self.symbols.is_empty() { return None; }
+        match self.symbols.binary_search_by_key(&address, |s| s.address) {
+            Ok(index) => self.symbols.get(index),
+            Err(index) => self.symbols.get(index.checked_sub(1)?),
+        }
+    }
+}
+
+
+pub struct DebugSymbol {
+    pub address: u16,
+    pub name: String,
+    pub location: Option<String>,
+}
+
+impl DebugSymbol {
+    pub fn from_line(line: &str) -> Option<Self> {
+        let (address, line) = line.split_once(' ')?;
+        let address = u16::from_str_radix(address, 16).ok()?;
+        if let Some((name, location)) = line.split_once(' ') {
+            let name = name.to_string();
+            let location = Some(location.to_string());
+            Some( DebugSymbol { address, name, location } )
+        } else {
+            let name = line.to_string();
+            Some( DebugSymbol { address, name, location: None } )
+        }
+    }
+}