From 50cd63aa387eb15f43215947777cba4254b38e4c Mon Sep 17 00:00:00 2001
From: SimonFJ20 <simonfromjakobsen@gmail.com>
Date: Sun, 30 Jul 2023 04:33:14 +0200
Subject: [PATCH] some gc stuff

---
 src/runtime.c | 116 ++++++++++++++++++++++++++++++++++++++++++++++++++
 src/runtime.h |  26 ++++++++---
 2 files changed, 135 insertions(+), 7 deletions(-)

diff --git a/src/runtime.c b/src/runtime.c
index ef3f730..a58f4c0 100644
--- a/src/runtime.c
+++ b/src/runtime.c
@@ -1,5 +1,6 @@
 #include "runtime.h"
 #include "lexer.h"
+#include <stdlib.h>
 #include <string.h>
 
 void value_vec_construct(ValueVec* vec, Allocator* allocator)
@@ -133,3 +134,118 @@ void value_stringify(const Value* value, String* acc)
             break;
     }
 }
+
+void gc_buffer_construct(GCBuffer* buffer, size_t capacity)
+{
+    void* data = malloc(capacity);
+    ASSERT(buffer != NULL);
+    *buffer = (GCBuffer) {
+        .data = data,
+        .capacity = capacity,
+    };
+}
+
+void gc_buffer_destroy(GCBuffer* buffer) { free(buffer->data); }
+
+void gc_buffer_resize(GCBuffer* buffer, size_t minimum_capacity)
+{
+    if (buffer->capacity >= minimum_capacity) {
+        return;
+    }
+    while (buffer->capacity < minimum_capacity) {
+        buffer->capacity *= 2;
+    }
+    void* new_buffer = realloc(buffer->data, buffer->capacity);
+    ASSERT(new_buffer);
+    buffer->data = new_buffer;
+}
+
+void gc_construct(GC* allocator, size_t start_capacity)
+{
+    GCBuffer buffer_a;
+    gc_buffer_construct(&buffer_a, start_capacity);
+    GCBuffer buffer_b;
+    gc_buffer_construct(&buffer_b, start_capacity);
+    *allocator = (GC) {
+        .alloc = gc_alloc,
+        .realloc = gc_realloc,
+        .buffer_a = buffer_a,
+        .buffer_b = buffer_b,
+        .select = GCBufferA,
+        .index = 0,
+    };
+}
+
+void gc_destroy(GC* allocator)
+{
+    gc_buffer_destroy(&allocator->buffer_a);
+    gc_buffer_destroy(&allocator->buffer_b);
+}
+
+void* gc_alloc(GC* allocator, size_t size)
+{
+    GCBuffer* buffer = gc_selected_buffer(allocator);
+    if (buffer->capacity < allocator->index + size) {
+        return NULL;
+    }
+    void* ptr = &buffer->data[allocator->index];
+    allocator->index += size;
+    return ptr;
+}
+
+void* gc_realloc(GC* allocator, void* data, size_t size)
+{
+    void* new_ptr = gc_alloc(allocator, size);
+    if (new_ptr == NULL) {
+        return NULL;
+    }
+    memcpy(new_ptr, data, size);
+    return new_ptr;
+}
+
+void* gc_collect(GC* allocator, ValueVec* stack, size_t to_be_allocated)
+{
+    GCBuffer* selected = gc_selected_buffer(allocator);
+    GCBuffer* other = gc_other_buffer(allocator);
+}
+
+GCBuffer* gc_selected_buffer(GC* allocator)
+{
+    switch (allocator->select) {
+        case GCBufferA:
+            return &allocator->buffer_a;
+        case GCBufferB:
+            return &allocator->buffer_b;
+    }
+}
+
+GCBuffer* gc_other_buffer(GC* allocator)
+{
+    switch (allocator->select) {
+        case GCBufferA:
+            return &allocator->buffer_b;
+        case GCBufferB:
+            return &allocator->buffer_a;
+    }
+}
+
+void gc_select_other(GC* allocator)
+{
+    switch (allocator->select) {
+        case GCBufferA:
+            allocator->select = GCBufferB;
+            break;
+        case GCBufferB:
+            allocator->select = GCBufferA;
+            break;
+    }
+}
+
+void runtime_construct(Runtime* runtime, Allocator* allocator)
+{
+    *runtime = (Runtime) {
+        .allocator = allocator,
+    };
+}
+
+void runtime_destroy(Runtime* runtime) { }
diff --git a/src/runtime.h b/src/runtime.h
index 93fcda9..712f093 100644
--- a/src/runtime.h
+++ b/src/runtime.h
@@ -52,27 +52,39 @@ struct Value {
 void value_destroy(Value* value);
 void value_stringify(const Value* value, String* acc);
 
+typedef struct {
+    void* data;
+    size_t capacity;
+} GCBuffer;
+
+void gc_buffer_construct(GCBuffer* buffer, size_t capacity);
+void gc_buffer_destroy(GCBuffer* buffer);
+void gc_buffer_resize(GCBuffer* buffer, size_t minimum_capacity);
+
 typedef enum {
     GCBufferA,
     GCBufferB,
-} GCBuffer;
+} SelectedGCBuffer;
 
 typedef struct GC GC;
 struct GC {
     void* (*alloc)(GC* allocator, size_t size);
     void* (*realloc)(GC* allocator, void* data, size_t size);
-    void* a_buffer;
-    size_t a_capacity;
-    void* b_buffer;
-    size_t b_capacity;
-    size_t alloc_ptr;
-    GCBuffer selected_buffer;
+    GCBuffer buffer_a;
+    GCBuffer buffer_b;
+    SelectedGCBuffer select;
+    size_t index;
 };
 
 void gc_construct(GC* allocator, size_t start_capacity);
 void gc_destroy(GC* allocator);
 void* gc_alloc(GC* allocator, size_t size);
 void* gc_realloc(GC* allocator, void* data, size_t size);
+void* gc_collect(GC* allocator, ValueVec* stack, size_t to_be_allocated);
+
+GCBuffer* gc_selected_buffer(GC* allocator);
+GCBuffer* gc_other_buffer(GC* allocator);
+void gc_select_other(GC* allocator);
 
 typedef struct {
     Allocator* allocator;