1 files changed, 125 insertions, 0 deletions
diff --git a/src/types/metadata.rs b/src/types/metadata.rs
new file mode 100644
index 0000000..dde86fa
--- /dev/null
+++ b/src/types/metadata.rs
@@ -0,0 +1,125 @@
+use crate::*;
+
+
+const SMALL_ICON_LEN: usize = 3*3*8;
+const LARGE_ICON_LEN: usize = 8*8*8;
+
+pub fn parse_metadata(bytecode: &[u8]) -> Option<ProgramMetadata> {
+    MetadataParser::from_bytecode(bytecode).parse()
+}
+
+
+pub struct ProgramMetadata {
+    pub name: Option<String>,
+    pub version: Option<String>,
+    pub authors: Option<Vec<String>>,
+    pub description: Option<String>,
+    pub bg_colour: Option<Colour>,
+    pub fg_colour: Option<Colour>,
+    pub small_icon: Option<[u8; SMALL_ICON_LEN]>,
+    pub large_icon: Option<[u8; LARGE_ICON_LEN]>,
+}
+
+
+struct MetadataParser<'a> {
+    bytecode: &'a [u8],
+}
+
+impl<'a> MetadataParser<'a> {
+    pub fn from_bytecode(bytecode: &'a [u8]) -> Self {
+        Self { bytecode }
+    }
+
+    pub fn parse(self) -> Option<ProgramMetadata> {
+        // Verify metadata identifier.
+        let identifier = self.vec(0x00, 10);
+        if identifier != &[0x41,0x00,0x18,0x42,0x45,0x44,0x52,0x4F,0x43,0x4B] {
+            return None;
+        }
+
+        let (name, version) = if let Some(pointer) = self.pointer(0x0a) {
+            let string = self.string(pointer);
+            if let Some((name, version)) = string.split_once('/') {
+                 (Some(name.trim().to_string()), Some(version.trim().to_string()))
+            } else {
+                (Some(string.trim().to_string()), None)
+            }
+        } else {
+            (None, None)
+        };
+
+        let authors = self.pointer(0x0c).map(|p| {
+            self.string(p).lines().map(|s| s.trim().to_string()).collect()
+        });
+
+        let description = self.pointer(0x0e).map(|p| self.string(p));
+        let bg_colour = self.pointer(0x10).map(|p| self.colour(p));
+        let fg_colour = self.pointer(0x12).map(|p| self.colour(p));
+
+        let small_icon = if let Some(pointer) = self.pointer(0x14) {
+            let vec = self.vec(pointer, SMALL_ICON_LEN);
+            Some(vec.try_into().unwrap())
+        } else {
+            None
+        };
+
+        let large_icon = if let Some(pointer) = self.pointer(0x16) {
+            let vec = self.vec(pointer, LARGE_ICON_LEN);
+            Some(vec.try_into().unwrap())
+        } else {
+            None
+        };
+
+        let metadata = ProgramMetadata {
+            name, version, authors, description,
+            bg_colour, fg_colour, small_icon, large_icon,
+        };
+        return Some(metadata);
+    }
+
+    fn byte(&self, address: usize) -> u8 {
+        match self.bytecode.get(address) {
+            Some(byte) => *byte,
+            None => 0,
+        }
+    }
+
+    fn double(&self, address: usize) -> u16 {
+        u16::from_be_bytes([
+            self.byte(address),
+            self.byte(address + 1),
+        ])
+    }
+
+    fn pointer(&self, address: usize) -> Option<usize> {
+        match self.double(address) {
+            0 => None,
+            v => Some(v as usize),
+        }
+    }
+
+    fn vec(&self, address: usize, length: usize) -> Vec<u8> {
+        let mut vec = Vec::new();
+        for i in 0..length {
+            vec.push(self.byte(address + i));
+        }
+        return vec;
+    }
+
+    fn string(&self, address: usize) -> String {
+        let mut i = address;
+        while self.byte(i) != 0 {
+            i += 1;
+        }
+        let slice = &self.bytecode[address..i];
+        String::from_utf8_lossy(slice).to_string()
+    }
+
+    fn colour(&self, address: usize) -> Colour {
+        let double = self.double(address);
+        let r = (double >>  8 & 0xf) as u8 * 17;
+        let g = (double >>  4 & 0xf) as u8 * 17;
+        let b = (double       & 0xf) as u8 * 17;
+        Colour::from_rgb(r, g, b)
+    }
+}