From 0b0f407c9cfecf4aaa3511d1a1fb37ef96f380c8 Mon Sep 17 00:00:00 2001
From: Ryan Jones-Ward <sciguyryan@gmail.com>
Date: Fri, 5 Jul 2024 11:39:51 +0100
Subject: [PATCH] Some notes on the next chunk of compiler work.

---
 redox-core/src/compiling/compiler.rs   | 15 ++++++++++++++-
 redox-core/src/compiling/executable.rs | 12 ++++++++++++
 redox-core/src/compiling/mod.rs        |  1 +
 redox-terminal/src/main.rs             |  6 ++----
 4 files changed, 29 insertions(+), 5 deletions(-)
 create mode 100644 redox-core/src/compiling/executable.rs

diff --git a/redox-core/src/compiling/compiler.rs b/redox-core/src/compiling/compiler.rs
index 6d6193d..c7a4589 100644
--- a/redox-core/src/compiling/compiler.rs
+++ b/redox-core/src/compiling/compiler.rs
@@ -7,11 +7,14 @@ use crate::{
     utils,
 };
 
+use super::executable::Executable;
+
 pub struct Compiler {
     /// A vector containing the compiled bytecode.
     bytes: Vec<u8>,
 
     local_labels: Vec<String>,
+    data_labels: Vec<String>,
     global_labels: Vec<String>,
     label_positions: HashMap<String, usize>,
 }
@@ -21,6 +24,7 @@ impl Compiler {
         Self {
             bytes: Vec::new(),
             local_labels: Vec::new(),
+            data_labels: Vec::new(),
             global_labels: Vec::new(),
             label_positions: HashMap::new(),
         }
@@ -57,6 +61,12 @@ impl Compiler {
         let mut parser = AsmParser::new();
         parser.parse(assembly);
 
+        // TODO - the data section(s) should be compiled first because their size, once computed, is invariant.
+        // TODO - references to the contained data may be made in the labels found within the code.
+        // TODO - the data items should be added as labels to the data_labels list.
+
+        // TODO - all labelled jumps MUST to be offset by the size of the data sections!
+
         let mut instructions = parser.parsed_instructions;
 
         self.load_labels(&instructions);
@@ -64,7 +74,7 @@ impl Compiler {
         self.calculate_label_positions(&instructions);
 
         if optimize {
-            // TODO - optimizations should ideally go here.
+            // TODO - optimizations should go here.
         }
 
         // TODO - the calculate label positions method should be called here again.
@@ -76,6 +86,9 @@ impl Compiler {
 
         self.compile(&instructions);
 
+        // TODO - package the bytecode into an executable.
+        let executable = Executable::new();
+
         &self.bytes
     }
 
diff --git a/redox-core/src/compiling/executable.rs b/redox-core/src/compiling/executable.rs
new file mode 100644
index 0000000..c5ea2d9
--- /dev/null
+++ b/redox-core/src/compiling/executable.rs
@@ -0,0 +1,12 @@
+// The structure of the executable file is as follows:
+// [READ-ONLY DATA]
+// [DATA]
+// [CODE]
+
+pub struct Executable {}
+
+impl Executable {
+    pub fn new() -> Self {
+        Self {}
+    }
+}
diff --git a/redox-core/src/compiling/mod.rs b/redox-core/src/compiling/mod.rs
index 562c9f3..6659819 100644
--- a/redox-core/src/compiling/mod.rs
+++ b/redox-core/src/compiling/mod.rs
@@ -1,2 +1,3 @@
 pub mod compiler;
 pub mod decompiler;
+pub mod executable;
diff --git a/redox-terminal/src/main.rs b/redox-terminal/src/main.rs
index 3bded2e..4dcb8dc 100644
--- a/redox-terminal/src/main.rs
+++ b/redox-terminal/src/main.rs
@@ -65,21 +65,19 @@ fn main() {
     if cfg!(target_endian = "big") {
         panic!("currently unsupported");
     }
+
     let code = "section .text\r\npush 0\r\ncall :LABEL_1\r\nhlt\r\n:LABEL_1\r\nmov 0xdeadbeef, EAX\r\niret";
     let mut compiler = Compiler::new();
     let data = compiler.compile_assembly(code, true);
 
     /*let instructions = &[
-        /*// Indicate that we want to make a seeded random number generator.
+        // Indicate that we want to make a seeded random number generator.
         Instruction::OutU8Imm(0x1, 0x0),
         // Specify our seed.
         Instruction::OutU32Imm(0xdeadbeef, 0x0),
         // Read a PRNG from the device.
         Instruction::InU32Reg(0x0, RegisterId::EAX),
         Instruction::PushU32Imm(0xdeadbeef),
-        Instruction::Halt,*/
-        Instruction::MovU32ImmU32Reg(0x1, RegisterId::EAX),
-        //Instruction::AddU32ImmU32Reg(0x2, RegisterId::EAX),
         Instruction::Halt,
     ];