Add `cons`, `car` and `cdr` primitives

1 files changed, 65 insertions, 7 deletions

diff --git a/src/compiler.h b/src/compiler.h
index 7323f4d..070f24a 100644
--- a/src/compiler.h
+++ b/src/compiler.h
@@ -5,15 +5,24 @@
 #define PRELUDE_FILE "src/x86_64/prelude.asm"
 #define POSTLUDE_FILE "src/x86_64/postlude.asm"
 
-#define NIL_VAL      1
-#define BOOL_MASK    3
-#define BOOL_TAG     3
-#define BOOL_SHIFT   2
+#define HEAP_SIZE   MB(32)
+
+// Immediate constants.
+#define NIL_VAL      47
+#define BOOL_MASK    127
+#define BOOL_TAG     31
+#define BOOL_SHIFT   7
 #define TRUE_VAL     ((1 << BOOL_SHIFT) | BOOL_TAG)
 #define FALSE_VAL    ((0 << BOOL_SHIFT) | BOOL_TAG)
-#define FIXNUM_MASK  1
+#define FIXNUM_MASK  3
 #define FIXNUM_TAG   0
-#define FIXNUM_SHIFT 1
+#define FIXNUM_SHIFT 2
+
+// Heap allocated objects.
+#define STRING_MASK  7
+#define STRING_TAG   3
+#define PAIR_MASK    7
+#define PAIR_TAG     1
 
 void compile_object(Object *obj);
 void compile_fixnum(Object *obj);
@@ -269,6 +278,49 @@ compile_arithmetic_list(OpType op, Object* args) {
 }
 
 void
+compile_cons(Object *obj) {
+    printf("    ;; --> compile_cons\n");
+    // Store objects into the car and cdr.
+    compile_object(obj->head);
+    compile_object(obj->tail->head);
+    printf("    pop     rdx\n");
+    printf("    pop     rax\n");
+    printf("    mov     [rsi], rax\n");
+    printf("    mov     [rsi + 8], rdx\n");
+
+    // Push memory address of cons cell.
+    printf("    mov     rax, rsi\n");
+    printf("    or      rax, %ld\n", PAIR_TAG);
+    printf("    push    rax\n");
+
+    // Bump allocation register.
+    printf("    add     rsi, 16\n");
+    printf("    ;; <-- compile_cons\n");
+}
+
+void
+compile_car(Object *obj) {
+    printf("    ;; <-- compile_car\n");
+    compile_object(obj->head);
+    printf("    pop     rax\n");
+    printf("    and     eax, %ld\n", ~PAIR_MASK);
+    printf("    mov     rdx, [rax]\n");
+    printf("    push    rdx\n");
+    printf("    ;; <-- compile_car\n");
+}
+
+void
+compile_cdr(Object *obj) {
+    printf("    ;; <-- compile_cdr\n");
+    compile_object(obj->head);
+    printf("    pop     rax\n");
+    printf("    and     eax, %ld\n", ~PAIR_MASK);
+    printf("    mov     rdx, [rax + 8]\n");
+    printf("    push    rdx\n");
+    printf("    ;; <-- compile_cdr\n");
+}
+
+void
 compile_proc_call(Object *obj) {
     // TODO: Probably we want to use a hash table for these lookups that is
     // initialized at the start of the compilation procedure.
@@ -310,6 +362,12 @@ compile_proc_call(Object *obj) {
         compile_cmp_list(OP_GREATER_EQ, obj->tail);
     } else if (sv_equal(&obj->head->text, &STRING("<="))) {
         compile_cmp_list(OP_LESS_EQ, obj->tail);
+    } else if (sv_equal(&obj->head->text, &STRING("cons"))) {
+        compile_cons(obj->tail);
+    } else if (sv_equal(&obj->head->text, &STRING("car"))) {
+        compile_car(obj->tail);
+    } else if (sv_equal(&obj->head->text, &STRING("cdr"))) {
+        compile_cdr(obj->tail);
     } else {
         fprintf(stderr, "error: not implemented\n");
         exit(EXIT_FAILURE);
@@ -359,12 +417,12 @@ compile(Root *roots) {
     printf("%%define FIXNUM_MASK  %d\n", FIXNUM_MASK);
     printf("%%define FIXNUM_TAG   %d\n", FIXNUM_TAG);
     printf("%%define FIXNUM_SHIFT %d\n", FIXNUM_SHIFT);
+    printf("%%define HEAP_SIZE    %ld\n", HEAP_SIZE);
     printf("\n");
     emit_file(PRELUDE_FILE);
     for (size_t i = 0; i < array_size(roots); i++) {
         Object *root = roots[i];
         compile_object(root);
-        // OBJ_PRINT(root);
     }
     emit_file(POSTLUDE_FILE);
 }