From 6b217c07bf07e735eac6896cd1e3ba81a600eecc Mon Sep 17 00:00:00 2001
From: alexf05 <alexfechet16@gmail.com>
Date: Fri, 20 Mar 2026 12:10:55 +0000
Subject: [PATCH 1/4] lab-09/reading: Fix 32-bit leftover syntax and typos

Update memory-layout and calling-convention reading materials to
correctly reflect the 64-bit System V AMD64 ABI. Add the missing
`xor rax, rax` before variadic function calls and convert 32-bit
stack argument examples to 64-bit register arguments.

Fix #141

Signed-off-by: alexf05 <alexfechet16@gmail.com>
---
 labs/lab-09/reading/calling-convention.md  |  1 +
 labs/lab-09/reading/memory-layout-c-asm.md | 14 ++++++++++----
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/labs/lab-09/reading/calling-convention.md b/labs/lab-09/reading/calling-convention.md
index fafa9bab7..4d982dc81 100644
--- a/labs/lab-09/reading/calling-convention.md
+++ b/labs/lab-09/reading/calling-convention.md
@@ -49,6 +49,7 @@ main:
 
     mov rdi, fmt
     mov rsi, text
+    xor rax, rax
     call printf
 
     pop rbp
diff --git a/labs/lab-09/reading/memory-layout-c-asm.md b/labs/lab-09/reading/memory-layout-c-asm.md
index 82f45645c..2fea21f85 100644
--- a/labs/lab-09/reading/memory-layout-c-asm.md
+++ b/labs/lab-09/reading/memory-layout-c-asm.md
@@ -40,13 +40,19 @@ section .data
 text db "291 is the best!", 10, 0
 strformat db "%s", 0
 
-section .code
+section .text
+global main
 
 main:
-        push dword text
-        push dword strformat
+        push rbp
+        mov rbp, rsp
+
+        mov rdi, strformat
+        mov rsi, text
+        xor rax, rax
         call printf
-        add esp, 8
+
+        leave
         ret
 ```
 

From 2e3e935710088c26b6666ee506e3e11c7c14c12d Mon Sep 17 00:00:00 2001
From: alexf05 <alexfechet16@gmail.com>
Date: Fri, 20 Mar 2026 12:11:36 +0000
Subject: [PATCH 2/4] lab-09/tasks: Fix ABI violations and logical bugs in
 64-bit ports

Correct multiple issues introduced during the x86_64 transition:
- max-c-calls: Fix signedness comparison by using `jae` and fix
  pointer initialization bug in the solution. Revert support file.
- regs-preserve: Add required 16-byte stack alignment before calling
  printf and fix the order of stack restoration in the solution.

Fix #141

Signed-off-by: alexf05 <alexfechet16@gmail.com>
---
 .../tasks/max-assembly-calls/solution/main.asm      |  1 +
 .../tasks/max-assembly-calls/support/main.asm       | 13 +++++++++++--
 labs/lab-09/tasks/max-c-calls/solution/max.asm      |  4 ++--
 labs/lab-09/tasks/max-c-calls/support/max.asm       | 10 +++-------
 labs/lab-09/tasks/regs-preserve/solution/main.asm   |  6 +++---
 labs/lab-09/tasks/regs-preserve/support/main.asm    |  3 +++
 .../tasks/stack-frame/support/print_hello.asm       |  2 +-
 7 files changed, 24 insertions(+), 15 deletions(-)

diff --git a/labs/lab-09/tasks/max-assembly-calls/solution/main.asm b/labs/lab-09/tasks/max-assembly-calls/solution/main.asm
index ea28cd6b2..707810978 100644
--- a/labs/lab-09/tasks/max-assembly-calls/solution/main.asm
+++ b/labs/lab-09/tasks/max-assembly-calls/solution/main.asm
@@ -37,6 +37,7 @@ main:
     mov rdi, fmt
     mov rsi, rax
     mov edx, dword [pos]
+    xor rax, rax
     call printf
 
     ; set exit code 0 (in main)
diff --git a/labs/lab-09/tasks/max-assembly-calls/support/main.asm b/labs/lab-09/tasks/max-assembly-calls/support/main.asm
index d5228f675..707810978 100644
--- a/labs/lab-09/tasks/max-assembly-calls/support/main.asm
+++ b/labs/lab-09/tasks/max-assembly-calls/support/main.asm
@@ -7,7 +7,12 @@ section .data
     arr: dd 19, 7, 129, 87, 54, 218, 67, 12, 19, 99
     len: equ $-arr
 
-    fmt: db "max: %u", 10, 0
+    fmt: db "max: %u on position: %u", 10, 0
+
+section .bss
+    ; we are _reserving_ space for a double word (4 bytes)
+    ; but we are not initializing it; so it can't reside in .data
+    pos: resd 1
 
 section .text
 
@@ -23,12 +28,16 @@ main:
     shr rsi, 2
 
     mov rdi, arr
+    mov rdx, pos
     call get_max
 
-    ; print maximum value
+    ; print maximum value and its position
     ; NOTE: RAX holds the return value of get_max()
+    ; NOTE: pos written by get_max() at given memory address
     mov rdi, fmt
     mov rsi, rax
+    mov edx, dword [pos]
+    xor rax, rax
     call printf
 
     ; set exit code 0 (in main)
diff --git a/labs/lab-09/tasks/max-c-calls/solution/max.asm b/labs/lab-09/tasks/max-c-calls/solution/max.asm
index b0a4fce24..96424f888 100644
--- a/labs/lab-09/tasks/max-c-calls/solution/max.asm
+++ b/labs/lab-09/tasks/max-c-calls/solution/max.asm
@@ -14,7 +14,7 @@ get_max:
 
     ; initialize EAX with the first value as currently known maximum
     mov eax, [rdi]
-    mov [rdx], eax
+    mov dword [rdx], 0
 
     ; initialize RCX as loop counter for remaining elements
     mov rcx, rsi
@@ -23,7 +23,7 @@ get_max:
     ; loop over remaining array elements
 compare:
     cmp eax, [rdi + 4*rcx]
-    jge check_end
+    jae check_end
 
     ; update maximum and its position
     mov eax, [rdi + 4*rcx]
diff --git a/labs/lab-09/tasks/max-c-calls/support/max.asm b/labs/lab-09/tasks/max-c-calls/support/max.asm
index 1794c71ba..1a14a0d68 100644
--- a/labs/lab-09/tasks/max-c-calls/support/max.asm
+++ b/labs/lab-09/tasks/max-c-calls/support/max.asm
@@ -6,7 +6,7 @@ global get_max
 
 
 ; RDI = array pointer
-; RSI = array length
+; RSI = array lengthget_max
 get_max:
     push rbp
     mov  rbp, rsp
@@ -18,16 +18,12 @@ get_max:
     mov rcx, rsi
     dec rcx
 
-    ; loop over remaining array elements
 compare:
     cmp eax, [rdi + 4*rcx]
-    jge check_end
+    jae check_end              ; <-- Keep the unsigned fix here!
     mov eax, [rdi + 4*rcx]
 check_end:
     loop compare
 
-    ; result stored in RAX
-
     leave
-    ret
-
+    ret
\ No newline at end of file
diff --git a/labs/lab-09/tasks/regs-preserve/solution/main.asm b/labs/lab-09/tasks/regs-preserve/solution/main.asm
index be5df9353..83c18dd9b 100644
--- a/labs/lab-09/tasks/regs-preserve/solution/main.asm
+++ b/labs/lab-09/tasks/regs-preserve/solution/main.asm
@@ -44,12 +44,12 @@ next:
     mov rdi, newline
     call printf
 
-    ; restore preserved register
-    pop rbx
-
     ; restore the stack after calling printf
     add rsp, 8
 
+    ; restore preserved register
+    pop rbx
+
     leave
     ret
 
diff --git a/labs/lab-09/tasks/regs-preserve/support/main.asm b/labs/lab-09/tasks/regs-preserve/support/main.asm
index 1f5b8cfe8..b3a989e9f 100644
--- a/labs/lab-09/tasks/regs-preserve/support/main.asm
+++ b/labs/lab-09/tasks/regs-preserve/support/main.asm
@@ -36,10 +36,13 @@ next:
     ; pop rcx
     loop next
 
+    sub rsp, 8
     xor rax, rax
     mov rdi, newline
     call printf
 
+    add rsp, 8
+
     ; restore preserved register
     pop rbx
 
diff --git a/labs/lab-09/tasks/stack-frame/support/print_hello.asm b/labs/lab-09/tasks/stack-frame/support/print_hello.asm
index ecc3d902b..86b5de1af 100644
--- a/labs/lab-09/tasks/stack-frame/support/print_hello.asm
+++ b/labs/lab-09/tasks/stack-frame/support/print_hello.asm
@@ -17,4 +17,4 @@ print_hello:
     call printf
 
     leave
-    ret
+    ret
\ No newline at end of file

From d8dfaaf4e6b5840c32116ae0a949cec64cf2b7c5 Mon Sep 17 00:00:00 2001
From: alexf05 <alexfechet16@gmail.com>
Date: Fri, 17 Apr 2026 05:21:19 +0000
Subject: [PATCH 3/4] Modified max-c-calls-x86 to x86

Resolved seg fault in reg-preserve
Another minor changes

Signed-off-by: alexf05 <alexfechet16@gmail.com>
---
 labs/lab-09/reading/calling-convention.md     |  1 -
 .../tasks/max-c-calls-x86/solution/max.asm    | 43 ++++++++++++-------
 .../tasks/max-c-calls-x86/support/max.asm     | 35 +++++++++------
 .../lab-09/tasks/max-c-calls/solution/max.asm |  4 +-
 labs/lab-09/tasks/max-c-calls/support/max.asm | 10 +++--
 .../tasks/regs-preserve/support/main.asm      |  5 +--
 .../tasks/regs-preserve/tests/results.txt     |  0
 .../tasks/stack-frame/support/print_hello.asm |  2 +-
 8 files changed, 61 insertions(+), 39 deletions(-)
 create mode 100644 labs/lab-09/tasks/regs-preserve/tests/results.txt

diff --git a/labs/lab-09/reading/calling-convention.md b/labs/lab-09/reading/calling-convention.md
index 4d982dc81..31d57fd85 100644
--- a/labs/lab-09/reading/calling-convention.md
+++ b/labs/lab-09/reading/calling-convention.md
@@ -53,7 +53,6 @@ main:
     call printf
 
     pop rbp
-    xor rax, rax
     ret
 ```
 
diff --git a/labs/lab-09/tasks/max-c-calls-x86/solution/max.asm b/labs/lab-09/tasks/max-c-calls-x86/solution/max.asm
index b0a4fce24..b40eda8b7 100644
--- a/labs/lab-09/tasks/max-c-calls-x86/solution/max.asm
+++ b/labs/lab-09/tasks/max-c-calls-x86/solution/max.asm
@@ -5,33 +5,46 @@ section .text
 global get_max
 
 
-; RDI = array pointer
-; RSI = array length
-; RDX = pos pointer
+; EDI = array pointer
+; ESI = array length
+; EDX = pos pointer
 get_max:
-    push rbp
-    mov  rbp, rsp
+    push ebp
+    mov  ebp, esp
+
+    ; save registers
+    push edi
+    push esi
+
+    mov edi, [ebp + 8]
+    mov esi, [ebp + 12]
+    mov edx, [ebp + 16]
+
 
     ; initialize EAX with the first value as currently known maximum
-    mov eax, [rdi]
-    mov [rdx], eax
+    mov eax, [edi]
+    mov dword [edx], 0
 
-    ; initialize RCX as loop counter for remaining elements
-    mov rcx, rsi
-    dec rcx
+    ; initialize ECX as loop counter for remaining elements
+    mov ecx, esi
+    dec ecx
 
     ; loop over remaining array elements
 compare:
-    cmp eax, [rdi + 4*rcx]
-    jge check_end
+    cmp eax, [edi + 4*ecx]
+    jae check_end
 
     ; update maximum and its position
-    mov eax, [rdi + 4*rcx]
-    mov [rdx], ecx
+    mov eax, [edi + 4*ecx]
+    mov [edx], ecx
 check_end:
     loop compare
 
-    ; result stored in RAX
+    ; result stored in EAX
+
+    ; restore registers
+    pop esi
+    pop edi
 
     leave
     ret
diff --git a/labs/lab-09/tasks/max-c-calls-x86/support/max.asm b/labs/lab-09/tasks/max-c-calls-x86/support/max.asm
index 1794c71ba..a577d66de 100644
--- a/labs/lab-09/tasks/max-c-calls-x86/support/max.asm
+++ b/labs/lab-09/tasks/max-c-calls-x86/support/max.asm
@@ -5,29 +5,36 @@ section .text
 global get_max
 
 
-; RDI = array pointer
-; RSI = array length
+; EDI = array pointer
+; ESI = array length
 get_max:
-    push rbp
-    mov  rbp, rsp
+    push ebp
+    mov  ebp, esp
+
+    ; save registers
+    push edi
+    push esi
+
+    mov edi, [ebp + 8]
+    mov esi, [ebp + 12]
 
     ; initialize EAX with the first value as currently known maximum
-    mov eax, [rdi]
+    mov eax, [edi]
 
-    ; initialize RCX as loop counter for remaining elements
-    mov rcx, rsi
-    dec rcx
+    ; initialize ECX as loop counter for remaining elements
+    mov ecx, esi
+    dec ecx
 
-    ; loop over remaining array elements
 compare:
-    cmp eax, [rdi + 4*rcx]
-    jge check_end
-    mov eax, [rdi + 4*rcx]
+    cmp eax, [edi + 4*ecx]
+    jae check_end
+    mov eax, [edi + 4*ecx]
 check_end:
     loop compare
 
-    ; result stored in RAX
+    ; restore registers
+    pop esi
+    pop edi
 
     leave
     ret
-
diff --git a/labs/lab-09/tasks/max-c-calls/solution/max.asm b/labs/lab-09/tasks/max-c-calls/solution/max.asm
index 96424f888..b0a4fce24 100644
--- a/labs/lab-09/tasks/max-c-calls/solution/max.asm
+++ b/labs/lab-09/tasks/max-c-calls/solution/max.asm
@@ -14,7 +14,7 @@ get_max:
 
     ; initialize EAX with the first value as currently known maximum
     mov eax, [rdi]
-    mov dword [rdx], 0
+    mov [rdx], eax
 
     ; initialize RCX as loop counter for remaining elements
     mov rcx, rsi
@@ -23,7 +23,7 @@ get_max:
     ; loop over remaining array elements
 compare:
     cmp eax, [rdi + 4*rcx]
-    jae check_end
+    jge check_end
 
     ; update maximum and its position
     mov eax, [rdi + 4*rcx]
diff --git a/labs/lab-09/tasks/max-c-calls/support/max.asm b/labs/lab-09/tasks/max-c-calls/support/max.asm
index 1a14a0d68..1794c71ba 100644
--- a/labs/lab-09/tasks/max-c-calls/support/max.asm
+++ b/labs/lab-09/tasks/max-c-calls/support/max.asm
@@ -6,7 +6,7 @@ global get_max
 
 
 ; RDI = array pointer
-; RSI = array lengthget_max
+; RSI = array length
 get_max:
     push rbp
     mov  rbp, rsp
@@ -18,12 +18,16 @@ get_max:
     mov rcx, rsi
     dec rcx
 
+    ; loop over remaining array elements
 compare:
     cmp eax, [rdi + 4*rcx]
-    jae check_end              ; <-- Keep the unsigned fix here!
+    jge check_end
     mov eax, [rdi + 4*rcx]
 check_end:
     loop compare
 
+    ; result stored in RAX
+
     leave
-    ret
\ No newline at end of file
+    ret
+
diff --git a/labs/lab-09/tasks/regs-preserve/support/main.asm b/labs/lab-09/tasks/regs-preserve/support/main.asm
index b3a989e9f..a79f17199 100644
--- a/labs/lab-09/tasks/regs-preserve/support/main.asm
+++ b/labs/lab-09/tasks/regs-preserve/support/main.asm
@@ -27,7 +27,8 @@ print_reverse_array:
     mov rcx, rsi
 
 next:
-    ; TODO1: uncomment the following two lines
+    ; TODO1: uncomment push rcx and pop rcx.
+    ; Note: pushing rcx also aligns the stack to 16 bytes for printf.
     ; push rcx
     xor rax, rax
     mov esi, [rbx + 4*rcx - 4]
@@ -36,12 +37,10 @@ next:
     ; pop rcx
     loop next
 
-    sub rsp, 8
     xor rax, rax
     mov rdi, newline
     call printf
 
-    add rsp, 8
 
     ; restore preserved register
     pop rbx
diff --git a/labs/lab-09/tasks/regs-preserve/tests/results.txt b/labs/lab-09/tasks/regs-preserve/tests/results.txt
new file mode 100644
index 000000000..e69de29bb
diff --git a/labs/lab-09/tasks/stack-frame/support/print_hello.asm b/labs/lab-09/tasks/stack-frame/support/print_hello.asm
index 86b5de1af..ecc3d902b 100644
--- a/labs/lab-09/tasks/stack-frame/support/print_hello.asm
+++ b/labs/lab-09/tasks/stack-frame/support/print_hello.asm
@@ -17,4 +17,4 @@ print_hello:
     call printf
 
     leave
-    ret
\ No newline at end of file
+    ret

From 72527d115e4ab3d94b94b51122ce0fd64f3cf9c1 Mon Sep 17 00:00:00 2001
From: alexf05 <alexfechet16@gmail.com>
Date: Fri, 17 Apr 2026 05:28:57 +0000
Subject: [PATCH 4/4] fixing trailiing whitespace

for the reading materials

Signed-off-by: alexf05 <alexfechet16@gmail.com>
---
 labs/lab-09/reading/memory-layout-c-asm.md | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/labs/lab-09/reading/memory-layout-c-asm.md b/labs/lab-09/reading/memory-layout-c-asm.md
index 2fea21f85..a8b3c4c8f 100644
--- a/labs/lab-09/reading/memory-layout-c-asm.md
+++ b/labs/lab-09/reading/memory-layout-c-asm.md
@@ -44,16 +44,16 @@ section .text
 global main
 
 main:
-        push rbp
-        mov rbp, rsp
+	push rbp
+	mov rbp, rsp
 
-        mov rdi, strformat
-        mov rsi, text
-        xor rax, rax
-        call printf
+	mov rdi, strformat
+	mov rsi, text
+	xor rax, rax
+	call printf
 
-        leave
-        ret
+	leave
+	ret
 ```
 
 Note that the procedure is declared as global and is called `main` - the starting point of any C program.