September 2017 Update

Task/Fork/X86-Assembly/fork.x86

@@ -1,32 +1,71 @@
-extern fork
-extern printf
+; x86_64 linux nasm
+
+%include "/home/james/Desktop/ASM_LIB/Print.asm"
+%include "/home/james/Desktop/ASM_LIB/Sleep.asm"
+
+section .data
+
+parent: db "Parent: "
+child: db "Child: "
+newLine: db 10
 
 section .text
-	global _start
-	
-	_start:
-		call fork
-		cmp eax, 0
-		je _child
-		jg _parent
-		jmp _exit
-		
-		_parent:
-			push p_msg
-			call printf
-			jmp _exit
-		_child:
-			push c_msg
-			call printf
-			jmp _exit
-		
-		_exit:
-			push 0x1
-			mov eax, 1
-			push eax
-			int 0x80
-			ret
-			
-section .data
-c_msg		db "Printed from Child process",13,10,0
-p_msg		db "Printed from Parent process",13,10,0
+
+global _start
+
+_start:
+  mov rax, 57 ; fork syscall
+  syscall
+  cmp rax, 0 ; if the return value is 0, we're in the child process
+  je printChild
+
+  printParent: ; else it's the child's PID, we're in the parent
+
+    mov rax, 1
+    mov rdi, 1
+    mov rsi, parent
+    mov rdx, 8
+    syscall
+
+    mov rax, 39 ; sys_getpid
+    syscall
+    mov rdi, rax
+    call Print_Unsigned
+
+    mov rax, 1
+    mov rdi, 1
+    mov rsi, newLine
+    mov rdx, 1
+    syscall
+
+    mov rdi, 1 ; sleep so the child process can print befor the parent exits
+    call Sleep ; you might not see the child output if you don't do this
+
+    jmp exit
+
+  printChild:
+
+    mov rdi, 1
+    call Sleep ; sleep and wait for parent to print to screen first
+
+    mov rax, 1
+    mov rdi, 1
+    mov rsi, child
+    mov rdx, 7
+    syscall
+
+    mov rax, 39 ; sys_getpid
+    syscall
+    mov rdi, rax
+    call Print_Unsigned
+
+    mov rax, 1
+    mov rdi, 1
+    mov rsi, newLine
+    mov rdx, 1
+    syscall
+
+  exit:
+    mov rax, 60
+    mov rdi, 0
+    syscall