From c400fb5593765a74d7eabc8142a9d7957fd7c51c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=AB=8F=E8=A8=AA=E5=AD=90?= <suwako@076.moe>
Date: Thu, 11 Dec 2025 02:56:15 +0900
Subject: [PATCH] =?UTF-8?q?=E6=9C=80=E5=88=9D=E3=82=B3=E3=83=9F=E3=83=83?=
 =?UTF-8?q?=E3=83=88?=
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---
 .gitignore |  3 +++
 Makefile   | 10 +++++++
 main.s     | 76 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 89 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Makefile
 create mode 100644 main.s

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..3cbf949
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+*.ppm
+*.o
+gen
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..d3034e3
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,10 @@
+all: build run
+
+build:
+	nasm -f elf64 main.s -o main.o
+	ld main.o -o gen
+
+run:
+	./gen
+
+.PHONY: all build run
diff --git a/main.s b/main.s
new file mode 100644
index 0000000..d393451
--- /dev/null
+++ b/main.s
@@ -0,0 +1,76 @@
+; FreeBSDで、死すコール番号を調べるには：/usr/include/sys/syscall.h
+; Linuxで、死すコール番号を調べるには：/usr/include/asm-generic/unistd.h
+; 下記のコードはFreeBSD向けの物です。
+
+bits 64
+default rel
+
+section .data
+  hdr2 db "960 540", 10
+  hdr3 db "255", 10
+
+section .rodata
+  outfile db "output.ppm", 0
+  hdr1 db "P6", 10
+  err db "開くに失敗", 10
+  errlen equ $-err
+
+  w equ 960
+  h equ 540
+
+section .text
+  global _start
+
+_start:
+  mov rax, 5          ; sys_openat
+  lea rdi, [outfile]
+  mov rsi, 0x100601   ; 0x100601 = 0001 0000 0000 0110 0000 0001 = 1048576 + 1024 + 512 + 1 = 1050113
+                      ;   O_WRONLY  = 0x0001
+                      ;   O_CREAT   = 0x0200
+                      ;   O_TRUNC   = 0x0400
+                      ;   O_CLOEXEC = 0x010000
+                      ; /usr/include/sys/fcntl.h
+  mov rdx, 0o666      ; chmod 666
+  syscall
+
+  test rax, rax
+  js error            ; エラーがあれば
+  mov rbx, rax        ; ファイルディスクリプターをrbxに保存
+
+  mov rax, 4          ; sys_write
+  mov rdi, rbx        ; fd
+  lea rsi, [hdr1]
+  mov rdx, 3
+  syscall
+
+  mov rax, 4
+  mov rdi, rbx
+  lea rsi, [hdr2]
+  mov rdx, 8
+  syscall
+
+  mov rax, 4
+  mov rdi, rbx
+  lea rsi, [hdr3]
+  mov rdx, 4
+  syscall
+
+  mov rax, 6          ; sys_close
+  mov rdi, rbx
+  syscall
+
+end:
+  mov rax, 1          ; sys_exit
+  xor rdi, rdi
+  syscall
+
+error:
+  mov rax, 4
+  mov rdi, 2          ; stderr
+  lea rsi, [err]
+  mov rdx, errlen
+  syscall
+
+  mov rax, 1
+  mov rdi, 1
+  syscall