So close...!

Makefile

@@ -8,7 +8,7 @@ DEVICE     = atmega328p
 # DEVICE     = atmega128
 CLOCK      = 16000000UL
 # OBJECTS    = src/arduino_io.o src/alist.o src/main.o src/print_form.o src/read_form.o src/types.o
-OBJECTS    = src/arduino_io.o src/print_form.o src/read_form.o src/types.o src/alist.o src/symbols.o src/gc.o src/main.o
+OBJECTS    = src/arduino_io.o src/print_form.o src/read_form.o src/types.o src/alist.o src/symbols.o src/gc.o src/debug.o src/main.o
 
 UNOTTY = /dev/ttyACM0
 UNOBAUD = 115200

include/uberlisp/debug.h

@@ -0,0 +1,12 @@
+#ifndef _UBERLISP_DEBUG_H
+#define _UBERLISP_DEBUG_H
+
+#include <stdio.h>
+#include <avr/pgmspace.h>
+#include <uberlisp/types.h>
+#include <uberlisp/print_form.h>
+
+void print_mem();
+void print_env(uptr_t env);
+
+#endif

include/uberlisp/gc.h

@@ -4,6 +4,7 @@
 #include <stdio.h>
 #include <avr/pgmspace.h>
 #include <uberlisp/types.h>
+#include <uberlisp/debug.h>
 
 void __GC__();
 

src/debug.c

@@ -0,0 +1,12 @@
+#include <uberlisp/debug.h>
+
+void print_mem() {
+    printf_P(PSTR("Total mem:\t%dB\nFree mem:\t%dB\tUsed mem:\t%dB\nCons mem:\t%dB\tSymbol mem:\t%dB\n"),
+             TOTALMEM(), FREEMEM(), USEDMEM(), CONSMEM(), SYMMEM());
+}
+
+void print_env(uptr_t env) {
+    printf_P(PSTR("env: "));
+    print_form(env);
+    printf_P(PSTR("\n"));
+}

src/gc.c

@@ -6,10 +6,15 @@ void __GC__() {
   do {
     printf_P(PSTR("Top of garbage loop.\n"));
     garbage = 0;
+
     uptr_t *cur = UPTR_PTR(CSTART_p);
     printf_P(PSTR("Marking..."));
     while (cur < PTREND_p) {
-      if (IS_CONS(*cur)) *UPTR_PTR(*cur) |= GC_FLAG;
+      if (IS_CONS(*cur)) {
+        Cons *cons = CONS_PTR(*cur);
+        cons->car |= GC_FLAG;
+        if (! IS_CADR(cons->cdr)) cons->cdr |= GC_FLAG;
+      }
       cur++;
     }
     printf_P(PSTR("Done!\n"));
@@ -18,31 +23,44 @@ void __GC__() {
     cur = UPTR_PTR(CSTART_p);
     printf_P(PSTR("Sweeping...\n"));
     while (cur < UPTR_PTR(CEND_p)) {
-      if (! (*cur & GC_FLAG)) {
+      if (! ((*cur & (GC_FLAG | CADR_FLAG)) || IS_NIL(*cur))) {
         garbage = 1;
         free_st = cur;
-        do {
-          ++cur;
-        } while (IS_CADR(*cur));
-        ++cur;
+
+        while (! (*cur & GC_FLAG) && cur < UPTR_PTR(CEND_p)) cur++;
+
+        if (IS_CADR(*cur)) *cur &= ~CADR_FLAG;
+        else while (IS_NIL(*cur) && cur < UPTR_PTR(CEND_p)) cur++;
+
         free_end = cur;
-        int free_bytes = (intptr_t)free_end - (intptr_t)free_st;
+
+        int free_bytes = (intptr_t)free_end - (intptr_t)free_st,
+          kept_bytes = (intptr_t)free_st - CSTART_p;
+
         printf_P(PSTR("Freeing %i bytes...\n"), free_bytes);
-        memmove(CPTR(CSTART_p + free_bytes), CPTR(CSTART_p), free_bytes);
+        printf_P(PSTR("free_st: %p\t free_end: %p\n"), free_st, free_end);
+
+        memmove(CPTR(CSTART_p + free_bytes), CPTR(CSTART_p), kept_bytes);
         memset(CPTR(CSTART_p), 0, free_bytes);
         CSTART_p += free_bytes;
-        for (; cur < PTREND_p; ++cur)
-          if (IS_CONS(*cur) && TO_PTR(*cur) < CSTART_p) *cur += free_bytes;
+
+        for (cur = UPTR_PTR(CSTART_p); cur < PTREND_p; ++cur)
+          if (IS_CONS(*cur) && TO_PTR(*cur) < UPTR(free_end)) *cur += free_bytes;
         cur = free_end;
+
       } else
-        ++cur;
+        cur++;
     }
     printf_P(PSTR("Done!\n"));
 
     printf_P(PSTR("Clearing GC bits..."));
     for (cur = UPTR_PTR(CSTART_p); cur < UPTR_PTR(CEND_p); ++cur)
       *cur &= ~GC_FLAG;
     printf_P(PSTR("Done!\n"));
+
   } while (garbage);
   printf_P(PSTR("GC Complete!\n"));
+  print_mem();
+  print_form(*UPTR_PTR(CEND_p + 2));
+  printf_P(PSTR("\n"));
 }

src/main.c

@@ -8,6 +8,7 @@
 #include <uberlisp/read_form.h>
 #include <uberlisp/print_form.h>
 #include <uberlisp/gc.h>
+#include <uberlisp/debug.h>
 
 #include <stdio.h>
 
@@ -262,20 +263,19 @@ int main() {
   uptr_t *env = refer(NIL);
   init_syms(env);
 
-  printf_P(PSTR("env: "));
-  print_form(*env);
-  printf_P(PSTR("\n"));
-
   uptr_t *form_p = refer(NIL);
   while(1) {
-    printf_P(PSTR("Total mem:\t%dB\nFree mem:\t%dB\tUsed mem:\t%dB\nCons mem:\t%dB\tSymbol mem:\t%dB\n"),
-             TOTALMEM(), FREEMEM(), USEDMEM(), CONSMEM(), SYMMEM());
+    print_env(*env);
+    print_mem();
+
     printf_P(PSTR("> "));
     *form_p = read_form(stdin);
     while(getc(stdin) != '\r');
     print_form(eval(env, *form_p));
     printf_P(PSTR("\n"));
-    //__GC__();
+
+    print_mem();
+    __GC__();
   }
 
   release(2); // Just a formality really...

src/types.c

@@ -104,7 +104,7 @@ void unhash_sym(char *buf, uptr_t sym_p) {
 uptr_t *refer(uptr_t uptr) {
   *PTREND_p = uptr;
   PTREND_p++;
-  printf_P(PSTR("SP: %p\tPTREND_p %p\n"), SP, PTREND_p);
+  //  printf_P(PSTR("SP: %p\tPTREND_p %p\n"), SP, PTREND_p);
   return PTREND_p - 1;
 }