From 565d50b639253cb833c6039eab36acd5700c8a6a Mon Sep 17 00:00:00 2001
From: servostar <sven.vogel123@web.de>
Date: Tue, 7 May 2024 15:24:42 +0200
Subject: [PATCH] added gc module

---
 src/ast/ast.c   |   1 +
 src/gc/gc.c     | 113 ++++++++++++++++++++++++++++++++++++++++++++++++
 src/gc/gc.h     |  24 ++++++++++
 src/lex/lexer.l |   1 +
 src/main.c      |   3 ++
 src/sys/log.h   |   2 +-
 6 files changed, 143 insertions(+), 1 deletion(-)
 create mode 100644 src/gc/gc.c
 create mode 100644 src/gc/gc.h

diff --git a/src/ast/ast.c b/src/ast/ast.c
index 6e4c106..a9c820b 100644
--- a/src/ast/ast.c
+++ b/src/ast/ast.c
@@ -3,6 +3,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/log.h>
+#include <gc/gc.h>
 
 struct AST_Node_t *AST_new_node(enum AST_SyntaxElement_t kind, const char* value) {
   DEBUG("creating new AST node: %d \"%s\"", kind, value);
diff --git a/src/gc/gc.c b/src/gc/gc.c
new file mode 100644
index 0000000..7648655
--- /dev/null
+++ b/src/gc/gc.c
@@ -0,0 +1,113 @@
+//
+// Created by servostar on 5/7/24.
+//
+
+#include <gc/gc.h>
+#include <sys/log.h>
+#include <string.h>
+
+#undef malloc
+#undef free
+#undef realloc
+
+#define GC_HEAP_PREALLOC_CNT 10
+
+typedef struct GC_Heap_Statistics_t {
+    size_t bytes;
+} GC_Heap_Statistics;
+
+static struct GC_Heap_t {
+    RAW_PTR* blocks;
+    size_t cap;
+    size_t len;
+    GC_Heap_Statistics statistics;
+} GC_GLOBAL_HEAP;
+
+static void __GC_teardown(void) {
+    INFO("Used %ld bytes in total", GC_GLOBAL_HEAP.statistics.bytes);
+
+    if (GC_GLOBAL_HEAP.blocks == NULL) {
+        return;
+    }
+
+    for (size_t i = 0; i < GC_GLOBAL_HEAP.len; i++) {
+        free(GC_GLOBAL_HEAP.blocks[i]);
+    }
+
+    free(GC_GLOBAL_HEAP.blocks);
+
+    GC_GLOBAL_HEAP.blocks = NULL;
+}
+
+static void __GC_check_init(void) {
+    if (GC_GLOBAL_HEAP.blocks == NULL) {
+        GC_GLOBAL_HEAP.cap = GC_HEAP_PREALLOC_CNT;
+        const size_t bytes = sizeof(RAW_PTR) * GC_GLOBAL_HEAP.cap;
+        GC_GLOBAL_HEAP.blocks = malloc(bytes);
+        GC_GLOBAL_HEAP.len = 0;
+    }
+}
+
+void GC_init(void) {
+    atexit(__GC_teardown);
+}
+
+static void __GC_check_overflow(void) {
+    if (GC_GLOBAL_HEAP.len >= GC_GLOBAL_HEAP.cap) {
+        GC_GLOBAL_HEAP.cap += GC_HEAP_PREALLOC_CNT;
+        const size_t bytes = sizeof(RAW_PTR) * GC_GLOBAL_HEAP.cap;
+        GC_GLOBAL_HEAP.blocks = realloc(GC_GLOBAL_HEAP.blocks, bytes);
+    }
+}
+
+RAW_PTR GC_malloc(const size_t bytes) {
+    const RAW_PTR ptr = malloc(bytes);
+
+    if (ptr == NULL) {
+        FATAL("unable to allocate memory");
+    }
+
+    __GC_check_init();
+    __GC_check_overflow();
+
+    GC_GLOBAL_HEAP.blocks[GC_GLOBAL_HEAP.len++] = ptr;
+
+    GC_GLOBAL_HEAP.statistics.bytes += bytes;
+
+    return ptr;
+}
+
+static void __GC_swap_ptr(RAW_PTR old, RAW_PTR new) {
+    for (size_t i = 0; i < GC_GLOBAL_HEAP.len; i++) {
+        if (GC_GLOBAL_HEAP.blocks[i] == old) {
+            GC_GLOBAL_HEAP.blocks[i] = new;
+        }
+    }
+}
+
+RAW_PTR GC_realloc(RAW_PTR ptr, size_t bytes) {
+    const RAW_PTR new_ptr = (RAW_PTR) realloc(ptr, bytes);
+
+    if (new_ptr == NULL) {
+        FATAL("unable to reallocate memory");
+    }
+
+    __GC_swap_ptr(ptr, new_ptr);
+
+    return new_ptr;
+}
+
+void GC_free(RAW_PTR ptr) {
+    DEBUG("freeing memory: %p", ptr);
+
+    for (size_t i = 0; i < GC_GLOBAL_HEAP.len; i++) {
+
+        if (ptr == GC_GLOBAL_HEAP.blocks[i]) {
+            free(GC_GLOBAL_HEAP.blocks[i]);
+
+            GC_GLOBAL_HEAP.len--;
+
+            memcpy(&GC_GLOBAL_HEAP.blocks[i], &GC_GLOBAL_HEAP.blocks[i + 1], GC_GLOBAL_HEAP.len - i);
+        }
+    }
+}
diff --git a/src/gc/gc.h b/src/gc/gc.h
new file mode 100644
index 0000000..6fe17a3
--- /dev/null
+++ b/src/gc/gc.h
@@ -0,0 +1,24 @@
+//
+// Created by servostar on 5/7/24.
+//
+
+#ifndef GC_H
+#define GC_H
+
+#include <stdlib.h>
+
+#define malloc GC_malloc
+#define free GC_free
+#define realloc GC_realloc
+
+typedef void* RAW_PTR;
+
+void GC_init(void);
+
+RAW_PTR GC_malloc(size_t bytes);
+
+RAW_PTR GC_realloc(RAW_PTR ptr, size_t bytes);
+
+void GC_free(RAW_PTR ptr);
+
+#endif //GC_H
diff --git a/src/lex/lexer.l b/src/lex/lexer.l
index 8823195..129af69 100644
--- a/src/lex/lexer.l
+++ b/src/lex/lexer.l
@@ -2,6 +2,7 @@
 %{
     #include <yacc/parser.tab.h>
     #include <sys/log.h>
+    #include <gc/gc.h>
 
     int yyLineNumber = 1;
     int yylex();
diff --git a/src/main.c b/src/main.c
index 1689ff0..0b56d88 100644
--- a/src/main.c
+++ b/src/main.c
@@ -2,6 +2,7 @@
 #include <sys/log.h>
 #include <yacc/parser.tab.h>
 #include <ast/ast.h>
+#include <gc/gc.h>
 
 #define LOG_LEVEL LOG_LEVEL_DEBUG
 
@@ -47,6 +48,8 @@ void setup(void)
     // actual setup
     AST_init();
 
+    GC_init();
+
     DEBUG("finished starting up gemstone...");
 }
 
diff --git a/src/sys/log.h b/src/sys/log.h
index aa18c88..3b4f7ed 100644
--- a/src/sys/log.h
+++ b/src/sys/log.h
@@ -2,7 +2,7 @@
 #define _SYS_ERR_H_
 
 #include <stdio.h>
-#include <string.h>
+#include <gc/gc.h>
 
 #define LOG_DEFAULT_STREAM stderr