From c308aa8ecce00fb0dd2606cbf482084876dc4910 Mon Sep 17 00:00:00 2001
From: Maciej Samborski <parys@hskl.org>
Date: Mon, 25 Nov 2024 17:38:47 +0100
Subject: [PATCH] Add cgc support

---
 cgc.h     | 114 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 da.h      |  34 +++++++++++++++-
 example.c |  19 ++++-----
 3 files changed, 157 insertions(+), 10 deletions(-)
 create mode 100644 cgc.h

diff --git a/cgc.h b/cgc.h
new file mode 100644
index 0000000..faba34d
--- /dev/null
+++ b/cgc.h
@@ -0,0 +1,114 @@
+#ifndef CGC_H_
+#define CGC_H_
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#define GC_DEFAULT_CAP 16
+#include <string.h>
+
+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 elemNo, size_t elemSize);
+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 = gc->capacity * 2;
+
+    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 elemNo, size_t elemSize)
+{
+    void * ptr = calloc(elemNo, elemSize);
+    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_
diff --git a/da.h b/da.h
index 37a1b9a..f9e9a56 100644
--- a/da.h
+++ b/da.h
@@ -10,6 +10,9 @@
 #define EHAN_IMPLEMENTATION
 #include "ehan.h"
 
+#define CGC_IMPLEMENTATION
+#include "cgc.h"
+
 enum daFields {
     SIZE          = 0,
     CAPACITY      = 1,
@@ -73,11 +76,29 @@ void daBzero(dynarr da);
 
 #ifdef DA_IMPLEMENTATION 
 
+#ifdef DA_GC
+GC daGarbageCollector = {0};
+
+void daInitGC()
+{
+    daGarbageCollector = gcInit();
+}
+
+void daDeinitGC()
+{
+    gcDeinit(daGarbageCollector);
+}
+#endif
+
 dynarr _daCreate(size_t cap, size_t type, size_t size)
 {
     size_t realCap = (((int)(cap / 8)) + 1 ) * 8;
-    
+#ifdef DA_GC
+    size_t * da = (size_t *) gcAlloc(&daGarbageCollector, 1, type * realCap + DATA * sizeof(size_t));
+#else
     size_t * da = (size_t *) calloc(1, type * realCap + DATA * sizeof(size_t));
+#endif
+    
     if (da == NULL)
         return NULL;
 
@@ -118,7 +139,18 @@ dynarr daResize(dynarr da)
         return NULL;
 
     memcpy(newArr, da, daSize(da) * daType(da));
+
+    // TODO: Make use of the GCIndex returned from gcAlloc !
+    for (size_t i = 0; i < daGarbageCollector.size; ++i)
+    {
+        if (daGarbageCollector.items[i].ptr == da)
+            gcUpdateItem(&daGarbageCollector, i, newArr);
+    }
+
+#ifndef DA_GC
     daFree(da);
+#endif
+
     return newArr;
 }
 
diff --git a/example.c b/example.c
index ce2f945..10ac9da 100644
--- a/example.c
+++ b/example.c
@@ -1,6 +1,7 @@
 #include <errno.h>
 #include <stdio.h>
 
+#define DA_GC
 #define DA_IMPLEMENTATION
 #include "da.h"
 
@@ -9,12 +10,14 @@
 
 int main(void)
 {
+    daInitGC();
+
     dynarr(int) da = daCreate(int, 8);
     dynarr(char *) da2 = daCreate(char *, 8);
     dynarr(float) da3 = daCreate(float, 1);
-    if (!da) goto cleanup;
-    if (!da2) goto cleanup;
-    if (!da3) goto cleanup;
+    if (!da) goto exit;
+    if (!da2) goto exit;
+    if (!da3) goto exit;
 
     printf("%zu %zu %zu\n", daSize(da), daCap(da), daType(da));
     printf("errno: %d\n", errno);
@@ -24,7 +27,7 @@ int main(void)
     printf("%zu %zu %zu\n", daSize(da), daCap(da), daType(da));
 
     da = daResize(da);
-    if (!da) goto cleanup;
+    if (!da) goto exit;
     printf("%zu %zu %zu\n", daSize(da), daCap(da), daType(da));
 
     printf("DA2 -----\n");
@@ -36,7 +39,7 @@ int main(void)
     for (size_t i = 0; i < N; ++i)
     {
         daAppend(da2, "AAA");
-        if (errno == 1) goto cleanup;
+        if (errno == 1) goto exit;
     }
 
     printf("%s%s\n", da2[0], da2[1]);
@@ -48,10 +51,8 @@ int main(void)
     daAppend(da3, 420.420);
     printf("%.2f:%.3f\n", da3[0], da3[1]);
 
-cleanup:
-    daFree(da3);
-    daFree(da2);
-    daFree(da);
+exit:
+    daDeinitGC();
 
     return 0;
 }