From 4273bdaeae1686bd4f411e283b7c9848046ffcae Mon Sep 17 00:00:00 2001
From: Kris Lamoureux <kris@lamoureux.io>
Date: Sun, 12 Oct 2025 21:25:54 -0400
Subject: [PATCH] External include files

---
 Makefile       |  1 +
 README.md      |  2 +-
 functions.asm  | 39 +++++++++++++++++++++++++++++++++++++++
 helloworld.asm | 46 +++++++++++-----------------------------------
 4 files changed, 52 insertions(+), 36 deletions(-)
 create mode 100644 functions.asm

diff --git a/Makefile b/Makefile
index b58f7a6..1d8d4dc 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,7 @@
 .PHONY: all clean
 
 SRC := $(wildcard *.asm)
+SRC := $(filter-out functions.asm, $(SRC))
 OBJDIR := build
 OBJS := $(SRC:%.asm=$(OBJDIR)/%.o)
 BINS := $(SRC:%.asm=$(OBJDIR)/%)
diff --git a/README.md b/README.md
index bb5df86..c1d1ed9 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,3 @@
 # asm
 
-Build x86_64 assembly examples from [asmtutor.com](https://asmtutor.com)
+x86 assembly exercises using [asmtutor.com](https://asmtutor.com)
diff --git a/functions.asm b/functions.asm
new file mode 100644
index 0000000..3f85c2e
--- /dev/null
+++ b/functions.asm
@@ -0,0 +1,39 @@
+SYS_EXIT    equ 1
+SYS_WRITE   equ 4
+STDOUT      equ 1
+
+strlen:
+    push    ebx
+    mov     ebx, eax
+nextchar:
+    cmp     byte[eax], 0
+    jz      finished
+    inc     eax
+    jmp     nextchar
+finished:
+    sub     eax, ebx
+    pop     ebx
+    ret
+
+print:
+    push    ebx
+    push    ecx
+    push    edx
+
+    mov     ebx, eax
+    call    strlen
+    mov     edx, eax
+    mov     ecx, ebx
+    mov     ebx, STDOUT
+    mov     eax, SYS_WRITE
+    int     0x80
+
+    pop     edx
+    pop     ecx
+    pop     ebx
+    ret
+
+quit:
+    mov     ebx, 0
+    mov     eax, SYS_EXIT
+    int     0x80
diff --git a/helloworld.asm b/helloworld.asm
index 67c8edd..4fbd93b 100644
--- a/helloworld.asm
+++ b/helloworld.asm
@@ -1,39 +1,15 @@
-; Hello World Program - asmtutor.com
-; Compile with: nasm -f elf helloworld.asm
-; Link with (64 bit systems require elf_i386 option): ld -m elf_i386 helloworld.o -o helloworld
-; Run with: ./helloworld
+%include        'functions.asm'
 
-SECTION .data
-msg     db      'Hello, brave new world!', 0Ah     ; assign msg variable with your message string
+section .data
+msg1     db      "Hello, world!", 0Ah
+msg2     db      "Display a line of text", 0Ah
 
-SECTION .text
-global  _start
+section .text
+global _start
 
 _start:
-    mov     eax, msg
-    call    strlen
-
-    mov     edx, eax        ; our function leaves the result in EAX
-    mov     ecx, msg
-    mov     ebx, 1          ; STDOUT
-    mov     eax, 4          ; SYS_WRITE
-    int     80h
-
-    mov     ebx, 0          ; return 0
-    mov     eax, 1          ; SYS_EXIT
-    int     80h
-
-strlen:
-    push    ebx             ; preserve EBX while we use in this function
-    mov     ebx, eax        ; move the address in EAX into EBX
-
-nextchar:
-    cmp     byte [eax], 0   ; compare the byte pointed to by EAX at this address against zero (Zero is an end of string delimiter)
-    jz      finished        ; jump (if the zero flagged has been set) to the point in the code labeled 'finished'
-    inc     eax             ; increment the address in EAX by one byte (if the zero flagged has NOT been set)
-    jmp     nextchar        ; jump to the point in the code labeled 'nextchar'
-
-finished:
-    sub     eax, ebx
-    pop     ebx
-    ret
+    mov     eax, msg1
+    call    print
+    mov     eax, msg2
+    call    print
+    call    quit