From a95f1ee641c44e2cce57551ffe652286bff418d6 Mon Sep 17 00:00:00 2001
From: Maciej Samborski <parys@hskl.org>
Date: Mon, 25 Nov 2024 16:14:18 +0100
Subject: [PATCH] Initial commit

---
 cgc.h | 112 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 112 insertions(+)
 create mode 100644 cgc.h

diff --git a/cgc.h b/cgc.h
new file mode 100644
index 0000000..86ce103
--- /dev/null
+++ b/cgc.h
@@ -0,0 +1,112 @@
+#ifndef CGC_H_
+#define CGC_H_
+
+#include <stdio.h>
+
+#define GC_DEFAULT_CAP 16
+
+typedef struct {
+    void * ptr;
+    size_t id;
+} GCItem;
+
+typedef struct {
+    GCItem * items;
+    size_t size;
+    size_t capacity;
+} GC;
+
+typedef size_t GCIndex;
+
+GC gcInit(void);
+void gcDeinit(GC gc);
+void gcGrowBuffer(GC * gc);
+GCIndex gcAddItem(GC * gc, void * ptr);
+void * gcAlloc(GC * gc, size_t n);
+void gcUpdateItem(GC * gc, GCIndex id, void * ptr);
+void * gcGetPtrAt(GC gc, GCIndex id);
+
+#ifdef CGC_IMPLEMENTATION
+
+GC gcInit()
+{
+    void * items = calloc(GC_DEFAULT_CAP, sizeof(GCItem));
+    if (items == NULL) {
+        fprintf(stderr, "ERROR: Failed to allocate GC!\n");
+        exit(1);
+    }
+
+    return (GC) {
+        .items = items,
+        .size = 0,
+        .capacity = GC_DEFAULT_CAP,
+    };
+}
+
+void gcDeinit(GC gc)
+{
+    for (size_t i = 0; i < gc.size; ++i)
+        free(gc.items[i].ptr);
+
+    free(gc.items);
+}
+
+void gcGrowBuffer(GC * gc)
+{
+    if (gc->items == NULL)
+    {
+        fprintf(stderr, "ERROR: GC is not initialized!\n");
+        exit(1);
+    }
+
+    size_t newCap = (size_t) (gc->capacity * 1.5);
+
+    void * items = calloc(newCap, sizeof(GCItem));
+    if (items == NULL) {
+        fprintf(stderr, "ERROR: Failed to allocate GC!\n");
+        exit(1);
+    }
+    memcpy(items, gc->items, gc->capacity * sizeof(GCItem));
+    free(gc->items);
+    gc->items = items;
+    gc->capacity = newCap;
+}
+
+GCIndex gcAddItem(GC * gc, void * ptr)
+{
+    if (gc->size >= gc->capacity)
+        gcGrowBuffer(gc);
+
+    gc->size += 1;
+    gc->items[gc->size - 1] = (GCItem) {
+        .id = gc->size - 1,
+        .ptr = ptr,
+    };
+
+    return gc->size - 1;
+}
+
+void * gcAlloc(GC * gc, size_t n)
+{
+    void * ptr = calloc(1, n);
+    if (ptr == NULL) return NULL;
+
+    gcAddItem(gc, ptr);
+
+    return ptr;
+}
+
+void gcUpdateItem(GC * gc, GCIndex id, void * ptr)
+{
+    free(gc->items[id].ptr);
+    gc->items[id].ptr = ptr;
+}
+
+void * gcGetPtrAt(GC gc, GCIndex id)
+{
+    return gc.items[id].ptr;
+}
+
+#endif // CGC_IMPLEMENTATION
+
+#endif // CGC_H_