From b825931ce596080979b67575828f8f4a84a23b51 Mon Sep 17 00:00:00 2001
From: Anthony Foxclaw <35226681+tonytins@users.noreply.github.com>
Date: Sun, 9 Feb 2020 16:41:13 -0500
Subject: [PATCH] Support for memory allocation

- Corten now has basic support for memory allocation through with the ALOC code.
---
 src/assembler.rs                    |  5 +++++
 src/assembler/instruction_parser.rs |  2 +-
 src/vm.rs                           | 21 ++++++++++++++++++++-
 3 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/src/assembler.rs b/src/assembler.rs
index f4a9499..fd0a75d 100644
--- a/src/assembler.rs
+++ b/src/assembler.rs
@@ -44,6 +44,8 @@ pub enum Opcode {
     JMPF,
     /// Jump backward
     JMPB,
+    /// Allocate memory
+    ALOC,
     NOP,
 }
 
@@ -67,6 +69,7 @@ impl From<u8> for Opcode {
             14 => Opcode::LT,
             15 => Opcode::JMPE,
             16 => Opcode::NOP,
+            17 => Opcode::ALOC,
             _ => Opcode::IGL,
         }
     }
@@ -92,6 +95,7 @@ impl From<Opcode> for u8 {
             Opcode::GT => 14,
             Opcode::JMPE => 15,
             Opcode::NOP => 16,
+            Opcode::ALOC => 17,
             Opcode::IGL => 100,
         }
     }
@@ -116,6 +120,7 @@ impl<'a> From<CompleteStr<'a>> for Opcode {
             CompleteStr("lte") => Opcode::LTE,
             CompleteStr("lt") => Opcode::LT,
             CompleteStr("jmpe") => Opcode::JMPE,
+            CompleteStr("aloc") => Opcode::ALOC,
             CompleteStr("nop") => Opcode::NOP,
             _ => Opcode::IGL,
         }
diff --git a/src/assembler/instruction_parser.rs b/src/assembler/instruction_parser.rs
index 21b1d83..0c9cd1a 100644
--- a/src/assembler/instruction_parser.rs
+++ b/src/assembler/instruction_parser.rs
@@ -140,4 +140,4 @@ mod instruction_parser_test {
             ))
         );
     }
-}
+}
\ No newline at end of file
diff --git a/src/vm.rs b/src/vm.rs
index 6bb1595..9dfe1c8 100644
--- a/src/vm.rs
+++ b/src/vm.rs
@@ -8,7 +8,9 @@ pub struct VM {
     pc: usize,
     /// The byte of the program being ran
     pub program: Vec<u8>,
-    /// The remainer of the module used in the division opcode
+    /// Memory allocation
+    heap: Vec<u8>,
+    /// The remainder of the module used in the division opcode
     remainder: u32,
     /// The result of the last comparison operation
     equal_flag: bool,
@@ -21,6 +23,7 @@ impl VM {
             registers: [0; 32],
             pc: 0,
             program: vec![],
+            heap: vec![],
             remainder: 0,
             equal_flag: false,
         }
@@ -204,6 +207,12 @@ impl VM {
                 self.next_8_bits();
                 self.next_8_bits();
             }
+            Opcode::ALOC => {
+                let reg = self.next_8_bits() as usize;
+                let bytes = self.registers[reg];
+                let new_end = self.heap.len() as i32 + bytes;
+                self.heap.resize(new_end as usize, 0);
+            }
         }
         true
     }
@@ -260,6 +269,16 @@ mod vm_tests {
         assert_eq!(vm.registers[2], 2);
     }
 
+    #[test]
+    fn test_aloc_opcode()
+    {
+        let mut vm = get_test_vm();
+        vm.registers[0] = 1024;
+        vm.program = vec![17, 0, 0, 0];
+        vm.run_once();
+        assert_eq!(vm.heap.len(), 1024);
+    }
+
     #[test]
     fn test_eq_opcode() {
         let mut vm = get_test_vm();