comments

stages/lisp0/lisp1.asm

@@ -165,6 +165,11 @@ panic_abort:
     mov rax, 60
     syscall
 
+exit:
+    xor edi, edi
+    mov rax, 60
+    syscall
+
 ;; rdi: *u8
 strlen:
     xor rax, rax
@@ -276,6 +281,7 @@ getc_inner:
     xor dl, dl                  ; peeked_some = false
     ret
 
+    ;; returns the next byte from the input without advancing the cursor. returns 1 or 0 in dl depending on EOF
 peekc:
     call getc_inner
     lea rdi, [rel ifile]
@@ -288,6 +294,7 @@ peekc:
     mov word [rdi + 4], cx      ; peeked = Some(Some(c))
     ret
 
+;; returns the next byte from the input. returns 1 or 0 in dl depending on EOF
 getc:
     call getc_inner
     lea rdi, [rel ifile]
@@ -295,6 +302,12 @@ getc:
     and eax, 0xff
     ret
 
+is_eof:
+    call peekc
+    test dl, dl
+    setz al
+    ret
+
 ;; Allocator
 
 ;; allocates $rdi bytes worth of pages via mmap
@@ -500,6 +513,8 @@ heap_dealloc:
 is_ch:
     push rdi
     call peekc
+    test dl, dl
+    je .eof
     pop rdi
     mov dl, al                  ; cl = peekc()
     cmp al, ' '
@@ -511,6 +526,9 @@ is_ch:
     cmp al, dil
     setz al                     ; al = (al == dil)
     ret
+.eof:
+    xor eax, eax
+    ret
 
 ;; converts char $dil to a digit with radix $rsi, returning it in $edx. $al is set to 1 if the char is a valid digit, and 0 otherwise.
 to_digit:
@@ -534,21 +552,42 @@ to_digit:
     xor eax, eax
     ret
 
+skip_whitespaces:
+    call peekc
+    cmp al, ' '
+    ja .done
+    call getc
+    jmp skip_whitespaces
+.done:
+    ret
+
+skip_comment:
+    call peekc
+    cmp al, `;`
+    jne .done
+.loop:
+    call getc
+    cmp al, 10
+    jne .loop
+    call skip_whitespaces
+    jmp skip_comment
+.done:
+    ret
+
 ;; reads the next token from ifile into buf
 next_token:
     push r14
     xor r14, r14
     sub rsp, 8
     mov qword [rsp], 0          ; flags
-.skip_whitespaces:
+
-    mov rdi, ' '
+    call skip_whitespaces
-    call is_ch
+    call skip_comment
-    test al, al
+
-    jz .test_kw
-    call getc
-    jmp .skip_whitespaces
-.test_kw:
     call peekc
+    test dl, dl
+    jz .done
+    
     movzx ecx, al
     sub cl, `'`
     cmp cl, `)` - `'`
@@ -643,15 +682,18 @@ global parse_next_token
 parse_next_token:
     call next_token
 parse_cur_token:
-    cmp byte [rel buf], `(`
+    cmp al, `(`
     je parse_list
-    cmp byte [rel buf], `'`
+    cmp al, `'`
     je parse_quote
-    cmp byte [rel buf], `"`
+    cmp al, `"`
     je parse_string
-    cmp byte [rel buf], `\\`
+    cmp al, `\\`
     je parse_char
-    jmp parse_atom
+    cmp al, 0
+    jne parse_atom
+    xor eax, eax
+    ret
 
 
 parse_list:
@@ -3283,3 +3325,45 @@ p_typeof:
     mov rax, qword [rsp]        ; result
     add rsp, 8
     ret
+
+;; Entry
+
+open_file:
+    mov rax, 2           ; syscall: open
+    mov rsi, 0           ; flags: O_RDONLY
+    mov rdx, 0           ; mode
+    syscall
+    ret
+
+init_ifile:
+    mov esi, edi
+    lea rdi, [rel ifile]
+    jmp init_source
+
+global _interp_entry
+_interp_entry:
+    mov eax, dword [rsp]
+    lea rbx, [rsp + 8]
+    mov edi, 1
+    cmp eax, 2
+    jle .init_ifile
+    mov rdi, qword [rbx + 8]    ; argv[1]
+    call open_file
+    mov edi, eax                ; fd
+.init_ifile:
+    call init_ifile
+
+    call init_env
+    sub rsp, 8
+    mov qword [rsp], rsi        ; env
+
+.loop:
+    call parse_next_token
+    test eax, eax
+    jz .done
+    mov rdi, rax
+    mov rsp, qword [rsp]        ; env
+    call eval
+    jmp .loop
+.done:
+    call exit

stages/lisp0/test.rs

@@ -499,4 +499,18 @@ mod tests {
             eprintln!("{result:?}");
         }
     }
+
+    #[test]
+    fn eval_comment() {
+        let file = ManuallyDrop::new(File::open("tests/comment.l").unwrap());
+        unsafe {
+            init_source(&raw mut IFILE, file.as_raw_fd());
+            let expr = parse_next_token();
+            eprintln!("parsed: {:?}", expr);
+            let env = unsafe { *ENV_INIT };
+            let result = eval(expr, env);
+            eprint!("done: ");
+            eprintln!("{result:?}");
+        }
+    }
 }

stages/lisp0/tests/comment.l

@@ -0,0 +1,2 @@
+;; this is a comment
+(define x 10) ; this is another comment