diff --git a/assert.h b/assert.h
new file mode 100644
index 0000000..48beede
--- /dev/null
+++ b/assert.h
@@ -0,0 +1,7 @@
+#pragma once
+
+#if defined(__dreamcast__)
+#include "assert_dreamcast.h"
+#else
+#include "assert_hosted.h"
+#endif
diff --git a/assert_dreamcast.h b/assert_dreamcast.h
new file mode 100644
index 0000000..62158df
--- /dev/null
+++ b/assert_dreamcast.h
@@ -0,0 +1,41 @@
+#pragma once
+
+#include "printf.h"
+#include "class_file.h"
+
+#define assert(b)                                                       \
+  do {                                                                  \
+    if (!(b)) {                                                         \
+      printf("%s:%d %s: assertion `%s` failed\n", __FILE__, __LINE__, __func__, #b); \
+      while (1);                                                        \
+    }                                                                   \
+  } while (0);
+
+static inline void assert_print_string(struct constant * constant)
+{
+  for (int i = 0; i < constant->utf8.length; i++) {
+    printc(constant->utf8.bytes[i]);
+  }
+  printc('\n');
+}
+
+#define assertvm(vm, b) \
+do { \
+  if (!(b)) { \
+    printf("%s:%d %s: vm assertion `%s` failed\n", __FILE__, __LINE__, __func__, #b); \
+ \
+    struct class_entry * class_entry = vm->current_frame->class_entry; \
+    struct constant * class_constant = &class_entry->class_file->constant_pool[class_entry->class_file->this_class - 1]; \
+    assert(class_constant->tag == CONSTANT_Class); \
+    struct constant * class_name_constant = &class_entry->class_file->constant_pool[class_constant->class.name_index - 1]; \
+    assert(class_name_constant->tag == CONSTANT_Utf8); \
+    assert_print_string(class_name_constant); \
+ \
+    struct method_info * method_info = vm->current_frame->method; \
+    struct constant * method_name_constant = &class_entry->class_file->constant_pool[method_info->name_index - 1]; \
+    assert(method_name_constant->tag == CONSTANT_Utf8); \
+    assert_print_string(method_name_constant);               \
+ \
+    while (1); \
+  } \
+   } while (0);
diff --git a/assert_hosted.h b/assert_hosted.h
new file mode 100644
index 0000000..09dc5c0
--- /dev/null
+++ b/assert_hosted.h
@@ -0,0 +1,16 @@
+#pragma once
+
+extern void __assert_fail (const char *__assertion, const char *__file,
+			   unsigned int __line, const char *__function)
+     __attribute__ ((__noreturn__));
+
+#define __ASSERT_FUNCTION __func__
+
+#define assert(expr)							\
+  ({                                                                    \
+    if (!(expr))                                                        \
+      __assert_fail (#expr, __FILE__, __LINE__, __ASSERT_FUNCTION);	\
+  })
+
+#define fail(expr) \
+  (__assert_fail (#expr, __FILE__, __LINE__, __ASSERT_FUNCTION);)
diff --git a/ast.h b/ast.h
new file mode 100644
index 0000000..982c95d
--- /dev/null
+++ b/ast.h
@@ -0,0 +1,47 @@
+#pragma once
+
+struct token;
+
+struct expression {
+  struct token * constant;
+};
+
+enum statement_type {
+  STATEMENT_RETURN,
+  STATEMENT_IF,
+  STATEMENT_IF_ELSE,
+};
+
+struct statement;
+
+struct statement_return {
+  struct expression * expression;
+};
+
+struct statement_if {
+  struct expression * expression;
+  struct statement * statement;
+};
+
+struct statement_if_else {
+  struct expression * expression;
+  struct statement * statement;
+};
+
+struct statement {
+  enum statement_type type;
+  union {
+    struct statement_return * statement_return;
+    struct statement_if * statement_if;
+    struct statement_if_else * statement_if_else;
+  };
+};
+
+struct function_definition {
+  struct token * name;
+  struct statement * statements;
+};
+
+struct program {
+  struct function_definition * function_definition;
+};
diff --git a/grammar.txt b/grammar.txt
new file mode 100644
index 0000000..35763a8
--- /dev/null
+++ b/grammar.txt
@@ -0,0 +1,7 @@
+<program> ::= <function>
+<function> ::= "int" <identifier> "(" "void" ")" "{" <statement> "}"
+<statement> ::= "return" <exp> ";" | "if" "(" <exp> ")" <statement> [ "else" <statement> ]
+<statement> ::= "return" <exp> ";"
+<exp> ::= <int>
+<identifier> ::= ? An identifier token ?
+<int> ::= ? A constant token ?
diff --git a/malloc.c b/malloc.c
new file mode 100644
index 0000000..88433d4
--- /dev/null
+++ b/malloc.c
@@ -0,0 +1,33 @@
+#include "assert.h"
+#include "malloc.h"
+
+struct arena {
+  uint8_t * mem;
+  uint32_t size;
+  uint32_t ix;
+};
+
+static uint8_t class_mem[0x100000];
+
+struct arena class_arena = {
+  .mem = class_mem,
+  .size = (sizeof (class_mem)),
+  .ix = 0,
+};
+
+void malloc_class_arena_reset()
+{
+  class_arena.ix = 0;
+}
+
+void * malloc_class_arena(uint32_t size)
+{
+  if (size == 0)
+    return nullptr;
+
+  assert((class_arena.ix & (~3)) == class_arena.ix);
+  void * ptr = &class_arena.mem[class_arena.ix];
+  size = (size + 3) & (~3);
+  class_arena.ix += size;
+  return ptr;
+}
diff --git a/parser.c b/parser.c
new file mode 100644
index 0000000..2de949d
--- /dev/null
+++ b/parser.c
@@ -0,0 +1,35 @@
+#include "parser.h"
+#include "lexer.h"
+#include "assert.h"
+
+struct token_reader {
+  bool have_token;
+  struct token token;
+  struct lexer_state lexer_state;
+};
+
+struct token peek(struct token_reader * reader)
+{
+  if (reader->have_token) {
+    return reader->token;
+  } else {
+    reader->token = lexer_next_token(reader->lexer_state);
+    reader->have_token = true;
+    return reader->token;
+  }
+}
+
+struct token consume(struct token_reader * reader)
+{
+  struct token token = peek(reader);
+  reader->have_token = false;
+}
+
+void expect_type(struct token_reader * reader, enum token_type token_type)
+{
+  struct token token = consume(reader);
+  if (!(token->type == token_type)) {
+    printf("token->type=%d token_type=%d\n", token->type, token_type);
+    fail(token->type == token_type);
+  }
+}