add rt_realloc_align for posix_memalign

src/kservice.c

@@ -1698,6 +1698,62 @@ RT_WEAK void *rt_malloc_align(rt_size_t size, rt_size_t align)
 }
 RTM_EXPORT(rt_malloc_align);
 
+/**
+ * This function will change the size of previously allocated memory block,
+ * which address is aligned to the specified alignment size.
+ *
+ * @param rmem is the pointer to memory allocated by rt_malloc_align.
+ *
+ * @param newsize is the required new size.
+ *
+ * @param align is the alignment size.
+ *
+ * @return the changed memory block address.
+ */
+RT_WEAK void *rt_realloc_align(void *rmem, size_t newsize, rt_size_t align)
+{
+    void *real_ptr;
+
+    void *ptr;
+    void *align_ptr;
+    int uintptr_size;
+    rt_size_t align_size;
+
+    /* sizeof pointer */
+    uintptr_size = sizeof(void*);
+    uintptr_size -= 1;
+
+    /* align the alignment size to uintptr size byte */
+    align = ((align + uintptr_size) & ~uintptr_size);
+
+    /* get total aligned size */
+    align_size = ((newsize + uintptr_size) & ~uintptr_size) + align;
+
+    real_ptr = (void *) * (rt_ubase_t *)((rt_ubase_t)rmem - sizeof(void *));
+
+    ptr = rt_realloc(real_ptr, align_size);
+
+    if (ptr != RT_NULL)
+    {
+        /* the allocated memory block is aligned */
+        if (((rt_ubase_t)ptr & (align - 1)) == 0)
+        {
+            align_ptr = (void *)((rt_ubase_t)ptr + align);
+        }
+        else
+        {
+            align_ptr = (void *)(((rt_ubase_t)ptr + (align - 1)) & ~(align - 1));
+        }
+
+        /* set the pointer before alignment pointer to the real pointer */
+        *((rt_ubase_t *)((rt_ubase_t)align_ptr - sizeof(void *))) = (rt_ubase_t)ptr;
+
+        ptr = align_ptr;
+    }
+
+    return ptr;
+}
+
 /**
  * This function release the memory block, which is allocated by
  * rt_malloc_align function and address is aligned.