From 218546d26f02a87372f83f8775dbe9e5007521de Mon Sep 17 00:00:00 2001
From: Rodolfo Barcelli Jo <rodolfo.barcelli@gmail.com>
Date: Fri, 16 Jan 2026 17:36:44 +0800
Subject: [PATCH] initial commit

---
 .clangd     |  14 +++++++
 .gitignore  |   1 +
 becs.h      | 104 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 build.bat   |   1 +
 build.sh    |   1 +
 test/main.c |  34 +++++++++++++++++
 6 files changed, 155 insertions(+)
 create mode 100644 .clangd
 create mode 100644 .gitignore
 create mode 100644 becs.h
 create mode 100644 build.bat
 create mode 100644 build.sh
 create mode 100644 test/main.c

diff --git a/.clangd b/.clangd
new file mode 100644
index 0000000..fa3677e
--- /dev/null
+++ b/.clangd
@@ -0,0 +1,14 @@
+CompileFlags:
+  Add: [
+    "-Wall",
+    "-Wextra",
+    "-Werror",
+    "-DBECS_IMPLEMENTATION=1"]
+Diagnostics:
+  Suppress: [
+    "-Wunused-function",
+    "-Wunused-but-set-parameter",
+    "-Wunused-parameter",
+    "-Wunused-variable",
+    "-Wuninitialized",
+    "-Wunused-but-set-variable"]
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..a007fea
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+build/*
diff --git a/becs.h b/becs.h
new file mode 100644
index 0000000..503c355
--- /dev/null
+++ b/becs.h
@@ -0,0 +1,104 @@
+#ifndef BECS_H
+#define BECS_H
+
+
+#ifdef BECS_IMPLEMENTATION
+#include <stdint.h>
+
+typedef struct BECS_ComponentArray {
+    uint32_t lastEntityAdded;
+    size_t unitSize;
+    uint32_t length;
+    uint32_t capacity;
+    void *array;
+} BECS_ComponentArray;
+
+typedef struct BECS_Properties {
+    uint32_t maxEntities;
+    uint32_t numComponents;
+    size_t *componentSizes;
+} BECS_Properties;
+
+typedef struct BECS_ECS {
+    uint64_t *bitMasks;
+    BECS_Properties props;
+    BECS_ComponentArray *componentSets;
+} BECS_ECS;
+
+size_t BECS_GetMinMemorySize
+(BECS_Properties props)
+{
+    size_t totalSize = 0;
+    totalSize += sizeof(BECS_ECS);
+    totalSize += sizeof(BECS_ComponentArray) * props.numComponents;
+    for (uint32_t i = 0; i < props.numComponents; i++)
+    {
+        totalSize += props.componentSizes[i] * props.maxEntities;
+        totalSize += sizeof(uint64_t);
+    }
+    return totalSize;
+}
+
+BECS_ECS *BECS_Init
+(void *memory, size_t size, BECS_Properties *props)
+{
+    BECS_ECS *ecs = (BECS_ECS *)memory;
+    uint64_t *bitMasks = (uint64_t *)(ecs + 1);
+    BECS_ComponentArray *componentSets = (BECS_ComponentArray *)(bitMasks + props->maxEntities);
+    ecs->bitMasks = bitMasks;
+    ecs->componentSets = componentSets;
+    ecs->props = *props;
+
+    ecs->bitMasks = 0;
+    for (uint32_t i = 0; i < props->numComponents; i++)
+    {
+        ecs->componentSets[i].length = 0;
+    }
+    return ecs;
+}
+
+int32_t
+BECS_AddComponent(BECS_ECS *ecs, uint32_t entityID, uint64_t componentBitMask, void *component)
+{
+    int32_t result = 0;
+    if (componentBitMask == 0)
+    {
+        return result;
+    }
+
+    uint32_t componentType = 0;
+    while (!(componentBitMask & 1))
+    {
+        componentBitMask >>= 1;
+        componentType++;
+    }
+
+    ecs->bitMasks[entityID] = ecs->bitMasks[entityID] | componentBitMask;
+    uint32_t insertIndex = ecs->componentSets[componentType].length;
+    if (insertIndex > ecs->props.maxEntities)
+    {
+        return result;
+    }
+
+    size_t componentSize = ecs->props.componentSizes[componentType];
+    uint8_t *componentArray = (uint8_t *)ecs->componentSets[componentType].array;
+    uint8_t *source = (uint8_t *)component;
+    componentArray += componentSize;
+    while (componentSize > 0)
+    {
+        *componentArray = *source;
+        componentSize--;
+    }
+    ecs->componentSets[componentType].length++;
+    result = 1;
+
+    return result;
+}
+
+// int32_t
+// BECS_RemoveComponent()
+// {
+// }
+#endif
+
+#endif
diff --git a/build.bat b/build.bat
new file mode 100644
index 0000000..825ed05
--- /dev/null
+++ b/build.bat
@@ -0,0 +1 @@
+REM Build Script for BECS
diff --git a/build.sh b/build.sh
new file mode 100644
index 0000000..72cbea7
--- /dev/null
+++ b/build.sh
@@ -0,0 +1 @@
+# Build script for BECS
diff --git a/test/main.c b/test/main.c
new file mode 100644
index 0000000..d562a71
--- /dev/null
+++ b/test/main.c
@@ -0,0 +1,34 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#define BECS_IMPLEMENTATION
+#include "becs.h"
+
+typedef struct compA {
+	uint32_t thing;
+} compA;
+
+typedef struct compB {
+	uint32_t thing;
+} compB;
+
+int main(void) {
+	BECS_Properties EcsProps = {};
+
+	size_t componentSizes[2] = { 
+		sizeof(compA),
+		sizeof(compB),
+	};
+
+	EcsProps.componentSizes = componentSizes;
+	EcsProps.numComponents = 2;
+	EcsProps.maxEntities = 100;
+
+	size_t MinMemorySize = BECS_GetMinMemorySize(EcsProps);
+	printf("%llu\n", MinMemorySize);
+
+	BECS_ECS *ecs = malloc(MinMemorySize);
+	BECS_Init(ecs, MinMemorySize, &EcsProps);
+
+	printf("Initialized\n");
+}