From: Dylan Lloyd <dylan@dylansserver.com>
Date: Wed, 17 Oct 2012 05:15:24 +0000 (-0400)
Subject: added macro and function def/call to x32
X-Git-Url: https://disinclined.org/git/?a=commitdiff_plain;h=eb1ad3fd11a26d7a2cc124454e40790ed386d7ff;p=nasm.git

added macro and function def/call to x32
---

diff --git a/hello32.asm b/hello32.asm
index b6178a0..58304db 100644
--- a/hello32.asm
+++ b/hello32.asm
@@ -1,27 +1,39 @@
+%macro print 2           ; Declare a macro to print a string, with two arguments
+    mov eax,4            ; Put magic # for system call sys_write into rax
+    mov edi,1            ; Prepare arg 1 of sys_write, 1 - file descriptor of stdo
+    mov esi,%1           ; Prepare arg 2, a string reference
+    mov edx,%2           ; Prepare arg 3, string length, no deref. b/c constant 
+    int 80h              ; Call the kernel
+%endmacro
+
 section .data
-    hello:     db 'Hello, world.',10   ; declare initialized string with linefeed char
-    helloLen:  equ $-hello             ; declare and init. constant
-    done: db 0
+    hello:     db  'Hello, world.',10   ; declare initialized string with linefeed char
+    helloLen:  equ $-hello              ; declare and init. constant
+    done:      db  0
 
 section .text
-    global _start
+    global _start        ; Declare program entry point
+
+_print:
+    push ebp             ; Prologue, save stack pointer
+    mov ebp,esp          ; Get base pointer (start of arguments)
+    mov ebx,[ebp+8]      ; Get first argument (offset from base by the return address)
+    print ebx,helloLen   ; Macro, replaced inline
+    leave                ; Epilogue, equivalent to mov esp,ebp; pop ebp
+    ret                  ; Return control to caller
 
 _start:
-    movzx eax, byte [done]      ; Pad value of done to one byte and put in eax
-    cmp eax,1                   ; Compare eax with 1
-    jg myFirstASMLabel          ; Jump if greater than to myFirstASMLabel
-
-    mov byte [done], 1
-    
-    mov eax,4            ; Put magic # for system call sys_write into eax
-    mov ebx,1            ; Prepare arg 1 of sys_write, 1 - file descriptor of stdo
-    mov ecx,hello        ; Prepare arg 2, reference to string hello
-    mov edx,helloLen     ; Prepare arg 3, string length, no deref. b/c constant 
-    int 80h              ; Call the kernel
-;
+    cmp byte [done],1    ; Compare byte padded value of done with 1
+    jg exit              ; Jump if greater than to exit
 
-myFirstASMLabel:
+    mov byte [done], 1   ; Put 1 in done
+
+    push hello           ; Push the last argument of _print onto the stack
+    call _print          ; Call the function _print
+
+exit:
     mov eax,1            ; The system call for exit (sys_exit)
-    mov ebx,0            ; Exit with return code of 0 (no error)
+    mov edi,0            ; Exit with return code of 0 (no error)
     int 80h
 
+