diff --git a/README.md b/README.md
index 2ddc384..b2ab87f 100644
--- a/README.md
+++ b/README.md
@@ -21,22 +21,27 @@
 ```mermaid
 flowchart TB
     subgraph low
+        ringbuf[ringbuf<br>小数据或尽量不扩容]
+        rawbuf
+        
         darray
         linklist
         dlinklist
-        ringbuffer[ringbuffer<br>小数据或尽量不扩容]
     end
 
     subgraph hal
-        segarray[segarray<br>大数据扩容优先] --> darray
+        segarray[segarray<br>大数据扩容优先]
+
+        segarray -.-> ringbuf
+        segarray -.-> rawbuf
+
         string --> darray
         hashtable --> darray
     end
 
     subgraph adapter
-        deque -->|仅学习| dlinklist
         deque ==> segarray
-        deque --> ringbuffer
+        deque --> ringbuf
     end
 
     subgraph top
@@ -51,8 +56,8 @@ flowchart TB
     end
 
     subgraph embed
-        estack --> ringbuffer
-        equeue --> ringbuffer
+        estack --> ringbuf
+        equeue --> ringbuf
     end
 ```
 
@@ -62,9 +67,11 @@ flowchart TB
 |数据结构 |名称 |说明 |
 |---|---|---|
 | darray  | 动态数组 | 扩容
-| ringbuf   | 环形缓存区 | 扩容/固定容量
+| ringbuf   | 环形缓存区 | 扩容/外部缓存
 | linlist   | 单链表 | 
 | dlinlist   | 双向链表 |
+| rawbuf | 原始缓冲区 | 动态分配固定容量/外部缓存
+| segarray | 分段数组 | 扩容
 
 ### 容器结构
 |数据结构 |名称 |说明 |
@@ -76,8 +83,8 @@ flowchart TB
 ### 嵌入式结构
 |数据结构 |名称 |说明 |
 |---|---|---|
-| estack | 栈 | 固定容量
-| equeue  | 队列 | 固定容量
+| estack | 栈 | 外部缓存
+| equeue  | 队列 | 外部缓存
 
 
 ## 接口函数原型
@@ -86,7 +93,7 @@ flowchart TB
 struct* new(size_t obj_size, size_t capacity);  // 创建
 void free(struct**);                            // 释放
 
-bool init(size_t obj_size, size_t capacity, void *mem_pool);    // 静态初始化，支持传入内存池，不扩容
+bool init(size_t obj_size, size_t capacity, void *mem_base);    // 静态初始化，支持传入外部缓存
 
 // 外部实现
 int compare(void* obj1, void* obj2);    // 比较函数，若调用了和比较有关的接口，需要在初始化后配置（树、图必须）
diff --git a/doc/notes.md b/doc/notes.md
index 9520494..2f28351 100644
--- a/doc/notes.md
+++ b/doc/notes.md
@@ -1,8 +1,11 @@
 
 # notes
 
-## segarray
+## rawbuf
+> 只对malloc封装，方便对特定目标进行index访问
+- 特点：支持随机访问，不支持扩容
 
+## segarray
 1. 扩容方案1
 ```
 if map.full
diff --git a/include/rawbuf.h b/include/rawbuf.h
new file mode 100644
index 0000000..68c74f9
--- /dev/null
+++ b/include/rawbuf.h
@@ -0,0 +1,43 @@
+/**
+ * @file rawbuf.c
+ * @author wenjf (orig5826@163.com)
+ * @brief 
+ * @version 0.1
+ * @date 2026-05-15
+ * 
+ * @copyright Copyright (c) 2026
+ * 
+ */
+#ifndef _RAWBUF_H_
+#define _RAWBUF_H_
+
+#include "unicstl_internal.h"
+
+struct _rawbuf
+{
+    // -------------------- private --------------------
+    void *obj;
+    size_t _obj_size;
+    size_t _capacity;
+    bool _dynamic;
+    
+    void (*_destory)(struct _rawbuf *self);
+    // -------------------- public --------------------
+    // kernel -> random access
+    bool (*set)(struct _rawbuf *self, size_t index, const void *obj);       // O(1)
+    bool (*get)(struct _rawbuf *self, size_t index, void *obj);             // O(1)
+    const void* (*at)(struct _rawbuf *self, size_t index);                  // O(1)
+
+    // base
+    size_t (*capacity)(struct _rawbuf *self);
+};
+typedef struct _rawbuf *rawbuf_t;
+
+rawbuf_t rawbuf_new(size_t obj_size, size_t capacity);
+void rawbuf_free(rawbuf_t *rawbuf);
+
+#ifdef UNICSTL_STATIC_MEMORY
+bool rawbuf_init(struct _rawbuf *self, size_t obj_size, size_t capacity, void *mem_base);
+#endif
+
+#endif
diff --git a/include/ringbuf.h b/include/ringbuf.h
index 07cc787..b474223 100644
--- a/include/ringbuf.h
+++ b/include/ringbuf.h
@@ -70,7 +70,7 @@ ringbuf_t ringbuf_new(size_t obj_size, size_t capacity);
 void ringbuf_free(ringbuf_t* ringbuf);
 
 #ifdef UNICSTL_STATIC_MEMORY
-bool ringbuf_init(struct _ringbuf *self, size_t obj_size, size_t capacity, void *mem_pool);
+bool ringbuf_init(struct _ringbuf *self, size_t obj_size, size_t capacity, void *mem_base);
 #endif
 
 #endif
diff --git a/include/unicstl.h b/include/unicstl.h
index 7a45756..5176af6 100644
--- a/include/unicstl.h
+++ b/include/unicstl.h
@@ -22,6 +22,7 @@
 #include "linklist.h"
 #include "dlinklist.h"
 #include "ringbuf.h"
+#include "rawbuf.h"
 
 #include "segarray.h"
 
diff --git a/src/rawbuf.c b/src/rawbuf.c
new file mode 100644
index 0000000..41589d2
--- /dev/null
+++ b/src/rawbuf.c
@@ -0,0 +1,129 @@
+/**
+ * @file rawbuf.c
+ * @author wenjf (orig5826@163.com)
+ * @brief 
+ * @version 0.1
+ * @date 2026-05-15
+ * 
+ * @copyright Copyright (c) 2026
+ * 
+ */
+#include "rawbuf.h"
+
+static size_t rawbuf_capacity(struct _rawbuf *self)
+{
+    unicstl_assert(self != NULL);
+    return self->_capacity;
+}
+
+static bool rawbuf_set(struct _rawbuf *self, size_t index, const void *obj)
+{
+    unicstl_assert(self != NULL);
+    if (index >= self->capacity(self) || obj == NULL)
+    {
+        return false;
+    }
+    size_t offset = index * self->_obj_size;
+    memmove((char *)self->obj + offset, obj, self->_obj_size);
+    return true;
+}
+
+static bool rawbuf_get(struct _rawbuf *self, size_t index, void *obj)
+{
+    unicstl_assert(self != NULL);
+    if (index >= self->capacity(self) || obj == NULL)
+    {
+        return false;
+    }
+    size_t offset = index * self->_obj_size;
+    memmove(obj, (char *)self->obj + offset, self->_obj_size);
+    return true;
+}
+
+const void *rawbuf_at(struct _rawbuf *self, size_t index)
+{
+    unicstl_assert(self != NULL);
+    if (index >= self->capacity(self))
+    {
+        return false;
+    }
+    size_t offset = index * self->_obj_size;
+    return (const char *)self->obj + offset;
+}
+
+static void rawbuf_destory(struct _rawbuf *self)
+{
+    unicstl_assert(self != NULL);
+    if (self->obj != NULL && self->_dynamic == true)
+    {
+        free(self->obj);
+    }
+}
+
+bool rawbuf_init(struct _rawbuf *self, size_t obj_size, size_t capacity, void *mem_base)
+{
+    unicstl_assert(self != NULL);
+    unicstl_assert(obj_size > 0);
+    if(capacity == 0)
+    {
+        return false;
+    }
+
+    // -------------------- private --------------------
+    self->_obj_size = obj_size;
+    self->_capacity = capacity;
+
+    self->obj = mem_base;
+    self->_dynamic = false;
+
+    self->_destory = rawbuf_destory;
+    // -------------------- public --------------------
+    // kernel
+    self->set = rawbuf_set;
+    self->get = rawbuf_get;
+    self->at = rawbuf_at;
+
+    self->capacity = rawbuf_capacity;
+
+    // -------------------- malloc --------------------
+    if(self->obj == NULL)
+    {
+        self->obj = unicstl_malloc(capacity * obj_size);
+        if (self->obj == NULL)
+        {
+            return false;
+        }
+        self->_dynamic = true;
+    }
+    return true;
+}
+
+rawbuf_t rawbuf_new(size_t obj_size, size_t capacity)
+{
+    struct _rawbuf *rawbuf = NULL;
+    rawbuf = (struct _rawbuf *)unicstl_malloc(sizeof(struct _rawbuf));
+    if (rawbuf == NULL)
+    {
+        return NULL;
+    }
+
+    if (rawbuf_init(rawbuf, obj_size, capacity, NULL) != true)
+    {
+        free(rawbuf);
+        return NULL;
+    }
+    return rawbuf;
+}
+
+void rawbuf_free(rawbuf_t *rawbuf)
+{
+    if (rawbuf != NULL && *rawbuf != NULL)
+    {
+        if ((*rawbuf)->_destory != NULL)
+        {
+            (*rawbuf)->_destory((*rawbuf));
+        }
+        free(*rawbuf);
+        *rawbuf = NULL;
+    }
+}
diff --git a/src/ringbuf.c b/src/ringbuf.c
index c01a31f..f30e323 100644
--- a/src/ringbuf.c
+++ b/src/ringbuf.c
@@ -366,7 +366,7 @@ iterator_t ringbuf_iter(struct _ringbuf *self, enum _ringbuf_order order)
  * @return true
  * @return false
  */
-bool ringbuf_init(struct _ringbuf *self, size_t obj_size, size_t capacity, void *mem_pool)
+bool ringbuf_init(struct _ringbuf *self, size_t obj_size, size_t capacity, void *mem_base)
 {
     unicstl_assert(self != NULL);
     unicstl_assert(obj_size > 0);
@@ -376,20 +376,8 @@ bool ringbuf_init(struct _ringbuf *self, size_t obj_size, size_t capacity, void
     self->_size = 0;
     self->_capacity = capacity + 1;
 
-    if (mem_pool != NULL)
-    {
-        self->obj = (char *)mem_pool;
-        self->_dynamic = false;
-    }
-    else
-    {
-        self->obj = (char *)unicstl_malloc(self->_obj_size * self->_capacity);
-        if (self->obj == NULL)
-        {
-            return false;
-        }
-        self->_dynamic = true;
-    }
+    self->obj = mem_base;
+    self->_dynamic = false;
 
     self->_head = 0;
     self->_tail = 0;
@@ -427,6 +415,16 @@ bool ringbuf_init(struct _ringbuf *self, size_t obj_size, size_t capacity, void
     // -------------------- debug --------------------
     self->print = ringbuf_print;
 
+    // -------------------- malloc --------------------
+    if (mem_base == NULL)
+    {
+        self->obj = (char *)unicstl_malloc(self->_obj_size * self->_capacity);
+        if (self->obj == NULL)
+        {
+            return false;
+        }
+        self->_dynamic = true;
+    }
     return true;
 }
 
diff --git a/test/test.c b/test/test.c
index 847e542..fbf62c1 100644
--- a/test/test.c
+++ b/test/test.c
@@ -95,7 +95,8 @@ int main(int argc, char const *argv[])
     TEST_ADD(test_tree);
     TEST_ADD(test_graph);
 
-    TEST_ADD(test_segarray);
+    TEST_ADD(test_rawbuf);
+    // TEST_ADD(test_segarray);
     
     return UNITY_END();
 }
diff --git a/test/test.h b/test/test.h
index 14611f3..d2fbca0 100644
--- a/test/test.h
+++ b/test/test.h
@@ -47,10 +47,10 @@ void test_unicstl(void);
 void test_darray(void);
 void test_linklist(void);
 void test_dlinklist(void);
-void test_segarray(void);
-
 void test_ringbuf(void);
+void test_rawbuf(void);
 
+void test_segarray(void);
 void test_deque(void);
 
 void test_queue(void);
diff --git a/test/test_rawbuf.c b/test/test_rawbuf.c
new file mode 100644
index 0000000..d7380bc
--- /dev/null
+++ b/test/test_rawbuf.c
@@ -0,0 +1,204 @@
+/**
+ * @file test_rawbuf.c
+ * @author wenjf (orig5826@163.com)
+ * @brief 
+ * @version 0.1
+ * @date 2026-05-15
+ * 
+ * @copyright Copyright (c) 2026
+ * 
+ */
+#include "test.h"
+
+static void test_rawbuf_new(void)
+{
+    // if obj_size must > 0, illegal. so no test case.
+
+    rawbuf_t rawbuf = rawbuf_new(sizeof(int), 10);
+    TEST_ASSERT_NOT_NULL(rawbuf);
+    rawbuf_free(&rawbuf);
+    TEST_ASSERT_NULL(rawbuf);
+}
+
+static void test_rawbuf_new_invalid(void)
+{
+    rawbuf_t rawbuf = rawbuf_new(sizeof(int), 0);
+    TEST_ASSERT_NULL(rawbuf);
+}
+
+#ifdef UNICSTL_STATIC_MEMORY
+static void test_rawbuf_init(void)
+{
+    size_t i = 0;
+    const size_t len = 10;
+
+    int data[10];
+    int temp = 0;
+
+    struct _rawbuf rawbuf;
+    TEST_ASSERT_TRUE(rawbuf_init(&rawbuf, sizeof(int), len, data));
+    for (i = 0; i < len; i++)
+    {
+        size_t index = len - 1 - i;
+        TEST_ASSERT_TRUE(rawbuf.set(&rawbuf, index, &data[i]));
+
+        TEST_ASSERT_TRUE(rawbuf.get((rawbuf_t)&rawbuf, index, &temp));
+        TEST_ASSERT_EQUAL_INT(data[i], temp);
+    }
+    TEST_ASSERT_TRUE(rawbuf.set(&rawbuf, 0, &data[0]));
+}
+#endif
+
+static void test_rawbuf_set(void)
+{
+    int temp = 0;
+    int data[] = { 1,2,3,4,5,6,7,8,9,10 };
+    size_t len = sizeof(data) / sizeof(data[0]);
+    size_t i = 0;
+
+    rawbuf_t rawbuf = rawbuf_new(sizeof(int), len);
+
+    // set from start to end
+    for(i = 0; i < len; i++)
+    {
+        TEST_ASSERT_TRUE(rawbuf->set(rawbuf, i, &data[i]));
+
+        TEST_ASSERT_TRUE(rawbuf->get(rawbuf, i, &temp));
+        TEST_ASSERT_EQUAL_INT(data[i], temp);
+    }
+
+    temp = 0x11;
+    TEST_ASSERT_TRUE(rawbuf->set(rawbuf, 0, &temp));
+    temp = 0x22;
+    TEST_ASSERT_TRUE(rawbuf->set(rawbuf, 5, &temp));
+    temp = 0x33;
+    TEST_ASSERT_TRUE(rawbuf->set(rawbuf, 9, &temp));
+
+    TEST_ASSERT_TRUE(rawbuf->get(rawbuf, 0, &temp));
+    TEST_ASSERT_EQUAL_INT(0x11, temp);
+    TEST_ASSERT_TRUE(rawbuf->get(rawbuf, 5, &temp));
+    TEST_ASSERT_EQUAL_INT(0x22, temp);
+    TEST_ASSERT_TRUE(rawbuf->get(rawbuf, 9, &temp));
+    TEST_ASSERT_EQUAL_INT(0x33, temp);
+
+    rawbuf_free(&rawbuf);
+}
+
+static void test_rawbuf_set_invalid(void)
+{
+    int temp = 0;
+    int data[] = { 1,2,3,4,5,6,7,8,9,10 };
+    size_t len = sizeof(data) / sizeof(data[0]);
+    size_t i = 0;
+
+    rawbuf_t rawbuf = rawbuf_new(sizeof(int), len);
+    for(i = 0; i < len; i++)
+    {
+        rawbuf->set(rawbuf, i, &data[i]);
+    }
+
+    // ---------- invalid index ----------
+    temp = 0x11;
+    TEST_ASSERT_FALSE(rawbuf->set(rawbuf, -1, &temp));
+    TEST_ASSERT_FALSE(rawbuf->set(rawbuf, len, &temp));
+    TEST_ASSERT_FALSE(rawbuf->set(rawbuf, 999, &temp));
+
+    TEST_ASSERT_FALSE(rawbuf->set(rawbuf, 0, NULL));
+
+    rawbuf_free(&rawbuf);
+}
+
+static void test_rawbuf_at(void)
+{
+    int temp = 0;
+    int data[] = { 1,2,3,4,5,6,7,8,9,10 };
+    size_t len = sizeof(data) / sizeof(data[0]);
+    size_t i = 0;
+
+    rawbuf_t rawbuf = rawbuf_new(sizeof(int), len);
+    for(i = 0; i < len; i++)
+    {
+        rawbuf->set(rawbuf, i, &data[i]);
+    }
+
+    const int *p_int = NULL;
+    p_int = rawbuf->at(rawbuf, 0);
+    TEST_ASSERT_EQUAL_INT(1, *p_int);
+
+    p_int = rawbuf->at(rawbuf, 4);
+    TEST_ASSERT_EQUAL_INT(5, *p_int);
+
+    p_int = rawbuf->at(rawbuf, 9);
+    TEST_ASSERT_EQUAL_INT(10, *p_int);
+
+    TEST_ASSERT_NULL(rawbuf->at(rawbuf, 10));
+    TEST_ASSERT_NULL(rawbuf->at(rawbuf, -1));
+
+
+    //  warning: initialization discards 'const' qualifier from pointer target type
+    // int *p_int_warring = rawbuf->at(rawbuf, 0);
+
+    // !!! you should not do this.
+    int *p_int_warring = (int *)rawbuf->at(rawbuf, 0);
+    *p_int_warring = 100;
+
+    rawbuf->get(rawbuf, 0, &temp);
+    TEST_ASSERT_EQUAL_INT(100, temp);
+
+    rawbuf_free(&rawbuf);
+}
+
+static void test_rawbuf_struct(void)
+{
+    size_t i = 0;
+    struct _student data[] = {
+        "zhao", 1001, "qian", 1002, "sun",   1003, "li",   1004,
+        "zhou", 1005, "wu",   1006, "zheng", 1007, "wang", 1008,
+        "feng", 1009, "cheng",1010,
+    };
+    struct _student temp = {0};
+    size_t len = sizeof(data) / sizeof(data[0]);
+
+    rawbuf_t rawbuf = rawbuf_new(sizeof(struct _student), len);
+    TEST_ASSERT_NOT_NULL(rawbuf);
+    TEST_ASSERT_EQUAL_INT(len, rawbuf->capacity(rawbuf));
+
+    // set from end to start
+    for (i = 0; i < len; i++)
+    {
+        size_t index = len-1-i;
+        TEST_ASSERT_TRUE(rawbuf->set(rawbuf, index,  &data[i]));
+
+        TEST_ASSERT_TRUE(rawbuf->get(rawbuf, index, &temp));
+        TEST_ASSERT_EQUAL_INT(data[i].id, temp.id);
+        TEST_ASSERT_EQUAL_STRING(data[i].name, temp.name);
+    }
+    for (i = 0; i < len; i++)
+    {
+        size_t index = len-1-i;
+        TEST_ASSERT_TRUE(rawbuf->get(rawbuf, i, &temp));
+        TEST_ASSERT_EQUAL_INT(data[index].id, temp.id);
+        TEST_ASSERT_EQUAL_STRING(data[index].name, temp.name);
+    }
+    rawbuf_free(&rawbuf);
+    TEST_ASSERT_NULL(rawbuf);
+}
+
+void test_rawbuf(void)
+{
+    UnitySetTestFile(__FILE__);
+
+    // ---------- kernel ----------
+    RUN_TEST(test_rawbuf_new);
+    RUN_TEST(test_rawbuf_new_invalid);
+
+    RUN_TEST(test_rawbuf_init);
+
+    RUN_TEST(test_rawbuf_set);
+    RUN_TEST(test_rawbuf_set_invalid);
+
+    RUN_TEST(test_rawbuf_at);
+
+    // ---------- ext ----------
+    RUN_TEST(test_rawbuf_struct);
+}
diff --git a/test/test_segarray.c b/test/test_segarray.c
index 3cbe357..0925321 100644
--- a/test/test_segarray.c
+++ b/test/test_segarray.c
@@ -841,8 +841,8 @@ void test_segarray(void)
 //     RUN_TEST(test_segarray_init);
 // #endif
 
-    RUN_TEST(test_segarray_push_back);
-    RUN_TEST(test_segarray_push_back_invalid);
+    // RUN_TEST(test_segarray_push_back);
+    // RUN_TEST(test_segarray_push_back_invalid);
 
 //     RUN_TEST(test_segarray_push_front);
 //     RUN_TEST(test_segarray_push_front_invalid);