最初コミット

u64todec.s

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+section .text
+
+u64_to_dec:
+  mov rcx, 10
+  mov r8, rdi
+  lea rdi, [rdi + 0x13]
+
+  test rax, rax
+  jnz .convert
+  mov byte [rdi], '0'
+  dec rdi
+  jmp .pad
+
+.convert:
+  xor rdx, rdx
+  div rcx
+  add dl, '0'
+  mov [rdi], dl
+  dec rdi
+  test rax, rax
+  jnz .convert
+
+.pad:
+  inc rdi
+.pad_loop:
+  cmp rdi, r8
+  jbe .done
+  mov byte [rdi], ' '
+  inc rdi
+  jb .pad_loop
+
+.done:
+  ret