1 files changed, 21 insertions, 9 deletions

diff --git a/src/x86_64/prelude.asm b/src/x86_64/prelude.asm
index c314ba4..6bb6627 100644
--- a/src/x86_64/prelude.asm
+++ b/src/x86_64/prelude.asm
@@ -1,12 +1,3 @@
-;; Value types.
-%define NIL_VAL      1
-%define BOOL_MASK    3
-%define BOOL_TAG     3
-%define BOOL_SHIFT   2
-%define FIXNUM_MASK  1
-%define FIXNUM_TAG   0
-%define FIXNUM_SHIFT 1
-
 printdln:
     sar     rdi, FIXNUM_SHIFT
     sub     rsp, 40
@@ -84,6 +75,27 @@ true_str:
 false_str:
     db      "false", 10
 
+display:
+    ;; is nil?
+    mov     rax, rdi
+    cmp     rax, NIL_VAL
+    je      display_end
+
+    ; ;; is boolean?
+    mov     rax, rdi
+    and     rax, BOOL_MASK
+    cmp     rax, BOOL_TAG
+    jne     not_bool
+    call    printbool
+    ret
+not_bool:
+
+    ;; is fixnum?
+    mov     rax, rdi
+    call    printdln
+display_end:
+    ret
+
 global  _start
 _start:
     push NIL_VAL