From 14d71a07dafa023ba83c2bdc6837d4ecc9de12ba Mon Sep 17 00:00:00 2001
From: Irene Knapp <ireneista@irenes.space>
Date: Sun, 5 Oct 2025 22:07:40 -0700
Subject: hello works! yay

Force-Push: yes
Change-Id: I6c70991d16bd27da2b75ee0666203f043714a685
---
 hello.asm | 104 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 104 insertions(+)
 create mode 100644 hello.asm

(limited to 'hello.asm')

diff --git a/hello.asm b/hello.asm
new file mode 100644
index 0000000..ed5dd57
--- /dev/null
+++ b/hello.asm
@@ -0,0 +1,104 @@
+; fasmg hello.asm hello && chmod 755 hello && ./hello; echo $?
+
+macro mov.d target, source
+  match =eax?, target
+    db 0xB8
+    dd source
+  else match =edi?, target
+    db 0xBF
+    dd source
+  else match =rax?, target
+    db 0x48, 0xC7, 0xC0
+    dd source
+  else match =rdi, target
+    db 0x48, 0xC7, 0xC7
+    dd source
+  else
+    assert 0
+  end match
+end macro
+
+
+macro mov.q target, source
+  match =rdi, target
+    db 0x48, 0xBF
+    dq source
+  else match =rsi, target
+    db 0x48, 0xBE
+    dq source
+  else match =rdx, target
+    db 0x48, 0xBA
+    dq source
+  else
+    assert 0
+  end match
+end macro
+
+
+macro syscall
+  db 0x0F, 0x05
+;        0f                      two-byte escape
+;           05                   syscall ^ o64
+end macro
+
+
+
+
+org 0x08048000
+
+elf_header:
+; * denotes mandatory fields according to breadbox
+  db 0x7F, "ELF"                 ; *magic number
+  db 2                           ; 64-bit
+  db 1                           ; little-endian
+  db 1                           ; ELF header format version 1
+  db 0                           ; System-V ABI
+  db 8 dup 0                     ; (padding)
+
+  dw 2                           ; *executable
+  dw 0x3E                        ; *Intel x86-64
+  dd 1                           ; ELF format version
+
+  dq _start                      ; *entry point
+  dq program_header - $$         ; *program header offset
+  dq 0                           ; section header offset
+  dd 0                           ; processor flags
+  dw elf_header_size
+  dw program_header_entry_size   ; *
+  dw 1                           ; *number of program header entries
+  dw 0                           ; section header entry size
+  dw 0                           ; number of section header entries
+  dw 0                           ; section name string table index
+elf_header_size = $ - elf_header
+
+program_header:
+  dd 1                           ; *"loadable" segment type
+  dd 0x05                        ; *read+execute permission
+  dq 0                           ; *offset in file
+  dq $$                          ; *virtual address
+                                 ;   required, but can be anything, subject to
+                                 ;   alignment
+  dq 0                           ; physical address (ignored)
+  dq file_size                   ; *size in file
+  dq file_size                   ; *size in memory
+  dq 0                           ; segment alignment
+                                 ;   for relocation - will we be ASLR'd?
+program_header_entry_size = $ - program_header
+
+_start:
+  mov.d eax, 1
+  mov.q rdi, 1
+  mov.q rsi, greeting
+  mov.q rdx, greeting_size
+  syscall
+
+  mov.d eax, 60
+  mov.d edi, 0
+  syscall
+
+greeting:
+  db "Hello, Irenes!", 0x0A
+greeting_size = $ - greeting
+
+file_size = $ - $$
+
-- 
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