-;; Read a word from standard input. Returns pointer to string containing word as
-;; well as length.
-;;
-;; Results:
-;; * rdx = Length of string
-;; * rdi = Pointer to string buffer
-;;
-;; Clobbers pretty much everything.
-read_word:
-.skip_whitespace:
- ;; Read characters into .char_buffer until one of them is not whitespace.
- mov rax, 0
- mov rdi, 0
- mov rsi, .char_buffer
- mov rdx, 1
- syscall
-
- ;; We consider newlines and spaces to be whitespace.
- cmp [.char_buffer], ' '
- je .skip_whitespace
- cmp [.char_buffer], $A
- je .skip_whitespace
-
-.alpha:
- ;; We got a character that wasn't whitespace. Now read the actual word.
- mov [.length], 0
-
-.read_alpha:
- mov al, [.char_buffer]
- movzx rbx, [.length]
- mov rsi, .buffer
- add rsi, rbx
- mov [rsi], al
- inc [.length]
-
- mov rax, 0
- mov rdi, 0
- mov rsi, .char_buffer
- mov rdx, 1
- syscall
-
- cmp [.char_buffer], ' '
- je .end
- cmp [.char_buffer], $A
- jne .read_alpha
-
-.end:
- mov rdi, .buffer
- movzx rdx, [.length]
-
- ret
-