1 files changed, 74 insertions, 7 deletions

diff --git a/src/gas_assembly_generator.c b/src/gas_assembly_generator.c
index f09b60d..5091120 100644
--- a/src/gas_assembly_generator.c
+++ b/src/gas_assembly_generator.c
@@ -17,8 +17,10 @@
 #include "gas_assembly_generator.h"
 
 #include <assert.h>
+#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 static void
 gas_assembly_generator_binary_operation(gas_assembly_generator_t *gen, ast_binary_operation_t *binary_operation);
@@ -32,11 +34,41 @@ gas_assembly_generator_compile_literal(gas_assembly_generator_t *gen, ast_litera
 static void
 gas_assembly_generator_compile_return_stmt(gas_assembly_generator_t *gen, ast_return_stmt_t *return_stmt);
 
+static void
+gas_assembly_generator_compile_variable_declaration(gas_assembly_generator_t *gen,
+                                                    ast_variable_declaration_t *variable_declaration);
+
+static void
+gas_assembly_generator_compile_variable(gas_assembly_generator_t *gen, ast_variable_t *variable);
+
+typedef struct ref_entry_t
+{
+  ast_identifier_t *id;
+  int stack_offset;
+} ref_entry_t;
+
+// TODO: We need a destroy function for ref_entry.
+static ref_entry_t *
+ref_entry_new(void)
+{
+  ref_entry_t *entry = (ref_entry_t *)malloc(sizeof(ref_entry_t));
+
+  if (entry == NULL) {
+    fprintf(stderr, "ref_entry_new: Out of memory: %s\n", strerror(errno));
+    exit(EXIT_FAILURE);
+  }
+
+  return entry;
+}
+
+
 void
 gas_assembly_generator_init(gas_assembly_generator_t *gen, FILE *stream)
 {
   assert(gen && stream);
   gen->stream = stream;
+  gen->refs = vector_new();
+  gen->stack_offset = 0;
 }
 
 void
@@ -59,10 +91,10 @@ gas_assembly_generator_compile(gas_assembly_generator_t *gen, ast_node_t *ast)
       assert(false && "TODO: ast identifier not implemented yet");
       break;
     case AST_VARIABLE_DECLARATION:
-      assert(false && "TODO: ast variable declaration not implemented yet");
+      gas_assembly_generator_compile_variable_declaration(gen, &ast->data.variable_declaration);
       break;
     case AST_VARIABLE:
-      assert(false && "TODO: ast variable not implemented yet");
+      gas_assembly_generator_compile_variable(gen, &ast->data.variable);
       break;
     case AST_UNKOWN_NODE:
       assert(false && "unreachable");
@@ -82,10 +114,14 @@ gas_assembly_generator_compile_function(gas_assembly_generator_t *gen, ast_funct
   fprintf(gen->stream, ".global _start\n");
   fprintf(gen->stream, ".text\n");
   fprintf(gen->stream, "_start:\n");
+  fprintf(gen->stream, "  push %%rbp\n");
+  fprintf(gen->stream, "  mov %%rsp, %%rbp\n");
 
   for (size_t i = 0; i < func->body->size; i++) {
     gas_assembly_generator_compile(gen, vector_at(func->body, i));
   }
+
+  fprintf(gen->stream, "  pop %%rbp\n");
 }
 
 static void
@@ -95,9 +131,38 @@ gas_assembly_generator_compile_return_stmt(gas_assembly_generator_t *gen, ast_re
 
   gas_assembly_generator_compile(gen, return_stmt->argument);
 
-  fprintf(gen->stream, "  mov %%rax, %%rbx\n");
-  fprintf(gen->stream, "  mov $1, %%al\n");
-  fprintf(gen->stream, "  int $0x80\n");
+  fprintf(gen->stream, "  mov %%rax, %%rdi\n");
+  fprintf(gen->stream, "  mov $60, %%rax\n");
+  fprintf(gen->stream, "  syscall\n");
+}
+
+static void
+gas_assembly_generator_compile_variable_declaration(gas_assembly_generator_t *gen,
+                                                    ast_variable_declaration_t *variable_declaration)
+{
+  gen->stack_offset -= 8;
+  gas_assembly_generator_compile(gen, variable_declaration->value);
+
+  ref_entry_t *entry = ref_entry_new();
+  *entry = (ref_entry_t){ .id = &variable_declaration->identifier, .stack_offset = gen->stack_offset };
+  vector_push_back(gen->refs, entry);
+
+  fprintf(gen->stream, "  mov %%rax, %d(%%rbp)\n", entry->stack_offset);
+}
+
+static void
+gas_assembly_generator_compile_variable(gas_assembly_generator_t *gen, ast_variable_t *variable)
+{
+  ref_entry_t *entry = NULL;
+  for (int i = gen->refs->size - 1; i >= 0; --i) {
+    ref_entry_t *entry_tmp = (ref_entry_t *)vector_at(gen->refs, i);
+    if (entry_tmp->id == variable->identifier) {
+      entry = entry_tmp;
+      break;
+    }
+  }
+  assert(entry && "reference not found");
+  fprintf(gen->stream, "  mov %d(%%rbp), %%rax\n", entry->stack_offset);
 }
 
 static void
@@ -117,11 +182,13 @@ gas_assembly_generator_binary_operation(gas_assembly_generator_t *gen, ast_binar
 {
   gas_assembly_generator_compile(gen, binary_operation->right);
 
-  fprintf(gen->stream, "  push %%rax\n");
+  gen->stack_offset -= 8;
+  fprintf(gen->stream, "  mov %%rax, %d(%%rbp)\n", gen->stack_offset);
 
   gas_assembly_generator_compile(gen, binary_operation->left);
 
-  fprintf(gen->stream, "  pop %%rcx\n");
+  fprintf(gen->stream, "  mov %d(%%rbp), %%rcx\n", gen->stack_offset);
+  gen->stack_offset += 8;
 
   if (binary_operation->kind == AST_BINOP_ADITION) {
     fprintf(gen->stream, "  add %%rcx, %%rax\n");