X-Git-Url: https://git.rrq.au/?a=blobdiff_plain;f=impl.asm;h=67d11b57ac02a3b7378c6f87d6b0276d39c91b19;hb=4a9ccd4fd3b9b19c696a2f37e0b46eecc1fdd671;hp=9ad22789eb587a03da91ae3773427543006a6253;hpb=24d3a4952e2e2b6db7a64eb2a8caffd2976a02ee;p=rrq%2Fjonasforth.git

diff --git a/impl.asm b/impl.asm
index 9ad2278..67d11b5 100644
--- a/impl.asm
+++ b/impl.asm
@@ -1,14 +1,12 @@
-segment readable executable
+os_code_section
 
 macro printlen msg, len {
   push rsi
   add rsp, 8
 
-  mov rsi, msg
+  mov rcx, msg
   mov rdx, len
-  mov rax, 1
-  mov rdi, 1
-  syscall
+  call os_print_string
 
   sub rsp, 8
   pop rsi
@@ -23,12 +21,6 @@ macro print msg {
   printlen msg, msg#.len
 }
 
-macro exit code {
-  mov rax, $3C
-  mov rdi, code
-  syscall
-}
-
 struc string bytes {
   . db bytes
   .len = $ - .
@@ -75,55 +67,57 @@ find:
 .found:
   ret
 
-;; Read a word from standard input. Returns pointer to string containing word as
-;; well as length.
+;; Read a word from a buffer. Returns the buffer without the word, as well as
+;; the word that was read (including lengths).
 ;;
-;; Results:
-;;   * rdx = Length of string
-;;   * rdi = Pointer to string buffer
+;; Inputs:
+;;   * rsi = Input buffer
+;;   * rcx = Length of buffer
 ;;
-;; Clobbers pretty much everything.
-read_word:
+;; Outputs:
+;;   * rsi = Updated buffer
+;;   * rcx = Length of updated buffer
+;;   * rdi = Word buffer
+;;   * rdx = Length of word buffer
+pop_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
+  mov al, [rsi]
+  cmp al, ' '
+  je .got_whitespace
+  cmp al, $A
+  je .got_whitespace
+  jmp .alpha
+.got_whitespace:
+  ;; The buffer starts with whitespace; discard the first character from the buffer.
+  inc rsi
+  dec rcx
+  jmp .skip_whitespace
 
 .alpha:
   ;; We got a character that wasn't whitespace. Now read the actual word.
-  mov [.length], 0
+  mov rdi, rsi ; This is where the word starts
+  mov rdx, 1   ; Length of word
 
 .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], ' '
+  ;; Extract character from original buffer:
+  inc rsi
+  dec rcx
+
+  ;; When we hit whitespace, we are done with this word
+  mov al, [rsi]
+  cmp al, ' '
+  je .end
+  cmp al, $A
   je .end
-  cmp [.char_buffer], $A
-  jne .read_alpha
+
+  ;; It wasn't whitespace; add it to word buffer
+  inc rdx
+  jmp .read_alpha
 
 .end:
-  mov rdi, .buffer
-  movzx rdx, [.length]
+  ;; Finally, we want to skip one whitespace character after the word.
+  inc rsi
+  dec rcx
 
   ret
 
@@ -187,18 +181,14 @@ parse_number:
   pop rdi
   printlen rdi, [.length]
   newline
-  exit 100
+  mov rax, 100
+  call os_terminate
 
-segment readable writable
+os_data_section
 
 find.search_length dq ?
 find.search_buffer dq ?
 
-read_word.max_size = $FF
-read_word.buffer rb read_word.max_size
-read_word.length db ?
-read_word.char_buffer db ?
-
 parse_number.length dq ?
 parse_number.error_msg string "Invalid number: "