From 4c0d93398fbac9a83db040fdb05aaf88d4dea558 Mon Sep 17 00:00:00 2001
From: jmug <u.g.a.mariano@gmail.com>
Date: Fri, 31 Jan 2025 22:22:53 -0800
Subject: [PATCH] Implement readquad, writequad, fetchins and crack.

Signed-off-by: jmug <u.g.a.mariano@gmail.com>
---
 hw2/bin/simulator.ml     | 24 ++++++++++++++++++------
 hw2/test/studenttests.ml | 26 ++++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 6 deletions(-)

diff --git a/hw2/bin/simulator.ml b/hw2/bin/simulator.ml
index 673a10b..1d5ce5a 100644
--- a/hw2/bin/simulator.ml
+++ b/hw2/bin/simulator.ml
@@ -210,13 +210,20 @@ let map_addr_segfault (addr : quad) : int =
    are glued together.
 *)
 
-let readquad (m : mach) (addr : quad) : quad = failwith "readquad not implemented"
+let readquad (m : mach) (addr : quad) : quad =
+  int64_of_sbytes @@ Array.to_list @@ Array.sub m.mem (map_addr_segfault addr) 8
 
 let writequad (m : mach) (addr : quad) (w : quad) : unit =
-  failwith "writequad not implemented"
-;;
+  Array.blit (Array.of_list @@ sbytes_of_int64 w) 0 m.mem (map_addr_segfault addr) 8
+
+exception InvalidInstructinAlignment
+
+let fetchins (m : mach) (addr : quad) : ins =
+  let ins_byte = m.mem.(map_addr_segfault addr) in
+  match ins_byte with
+  | InsB0 i -> i
+  | _ -> raise InvalidInstructinAlignment
 
-let fetchins (m : mach) (addr : quad) : ins = failwith "fetchins not implemented"
 
 (* Compute the instruction result.
  * NOTE: See int64_overflow.ml for the definition of the return type
@@ -239,11 +246,16 @@ let interp_operands (m : mach) : ins -> int64 list =
 ;;
 
 let validate_operands : ins -> unit = function
-  | _ -> failwith "validate_operands not implemented"
+  (* TODO: Add validations, leaq can only take indirect operands for example *)
+  | _ -> ()
 ;;
 
 let crack : ins -> ins list = function
-  | _ -> failwith "crack not implemented"
+  | Pushq, [ op ] -> [Subq, [Imm (Lit 8L); Reg Rsp]; Movq, [op; Ind2 Rsp]]
+  | Popq, [ op ] -> [Movq, [Ind2 Rsp; op]; Addq, [Imm (Lit 8L); Reg Rsp]]
+  | Callq, [ op ] -> [Subq, [Imm (Lit 8L); Reg Rsp]; Movq, [Reg Rip; Ind2 Rsp]; Jmp, [op]]
+  | Retq, [] -> [Movq, [Ind2 Rsp; Reg Rip]; Addq, [Imm (Lit 8L); Reg Rsp]]
+  | i -> [ i ]
 ;;
 
 (* TODO: double check against spec *)
diff --git a/hw2/test/studenttests.ml b/hw2/test/studenttests.ml
index c8639f8..e77eb8a 100644
--- a/hw2/test/studenttests.ml
+++ b/hw2/test/studenttests.ml
@@ -44,12 +44,38 @@ let mov_ri =
  InsFrag;
  ]
 
+let crack_tests =
+  let open Asm in
+  let pu = (Pushq, [~$42]) in
+  let po = (Popq, [~%Rax]) in
+  let ca = (Callq, [Ind2 Rax]) in
+  let re = (Retq, []) in
+  [
+    ("crack_pushq", assert_eqf (fun() ->
+      crack pu) ([ Subq, [Imm (Lit 8L); Reg Rsp]
+                ; Movq, [~$42; Ind2 Rsp] ]));
+    ("crack_pop", assert_eqf (fun() ->
+      crack po) ([ Movq, [Ind2 Rsp; Reg Rax]
+                ; Addq, [Imm (Lit 8L); Reg Rsp] ]));
+    ("crack_call", assert_eqf (fun() ->
+      crack ca) ([ Subq, [Imm (Lit 8L); Reg Rsp]
+                ; Movq, [Reg Rip; Ind2 Rsp]
+                ; Jmp, [Ind2 Rax] ]));
+    ("crack retq", assert_eqf (fun() ->
+      crack re) ([ Movq, [Ind2 Rsp; Reg Rip]
+                ; Addq, [Imm (Lit 8L); Reg Rsp] ]));
+
+  ]
+
 let provided_tests : suite = [
   
   Test ("My Tests", [
     ("assert", test_my)
   ]);
 
+  Test ("Student provided crack tests", crack_tests);
+
+
   Test ("Student-Provided Big Test for Part III: Score recorded as PartIIITestCase", [
     
   ]);