first file

e61dd9a1db5b6c6df9b7bef21898b9ec81093306 · ovidiucs · Jul 29, 2018 22:47
+27 · 1 file changed
hello.asm +27 −0
diff --git a/hello.asm b/hello.asm
new file mode 100644
index 0000000..5e187f3
--- /dev/null
+++ b/hello.asm
@@ -0,0 +1,27 @@
+format ELF64 executable 3
+
+segment readable executable
+
+entry main
+
+main:
+  lea rdi, [msg]          ; load effective address of msg into rdi - 
+                          ; computes the effective address in memory (offset within a segment)
+                          ; of a source operand and places it in gp register
+                          ; useful for initializing RSI,ESI,RDI,EDI before the exection of
+                          ; string instructions
+  mov rax, 14             ; length of message into 'rax' register
+  mov rdx, rax            ; moving 'rax' value to 'rdx'
+  mov rsi, rdi            ; moving 'rdi' value to 'rsi'
+  mov rdi, 1              ; stdout
+  mov rax, 1              ; syswrite
+  syscall
+  xor rdi, rdi            ; exit code of 0 exclusive or / zeroing out the register
+  mov rax, 60             ; use sys.exit
+  syscall                 ; call OS 
+
+segment readable writable  ; this is where we put our data
+
+  msg db 'Hello World!', 0xA, 0            ; we call it message and declare bytes and say
+                                           ; 'Hello World'. 10 for newline character and end with 0
+                                           ; H e l l o\  W o r l d ! 0xA 0 - 14