pointer: rename align as align_up, and add align_down

alloc/raw/linear.hpp

@@ -48,7 +48,7 @@ namespace cruft::alloc::raw {
         {
             auto const bytes = count * sizeof (T);
 
-            auto ptr = cruft::align (m_cursor, alignment);
+            auto ptr = cruft::align_up (m_cursor, alignment);
             if (ptr + bytes > m_end)
                 throw std::bad_alloc ();
 

alloc/raw/stack.hpp

@@ -40,7 +40,7 @@ namespace cruft::alloc::raw {
 
             // align the outgoing pointer if required
             alignment = cruft::max (MIN_ALIGNMENT, alignment);
-            ptr = cruft::align (ptr, alignment);
+            ptr = cruft::align_up (ptr, alignment);
 
             // ensure we haven't overrun our allocated segment
             if (ptr + bytes > m_end)

pointer.hpp

@@ -6,10 +6,7 @@
  * Copyright 2011-2017 Danny Robson <danny@nerdcruft.net>
  */
 
-#ifndef CRUFT_UTIL_POINTER_HPP
-#define CRUFT_UTIL_POINTER_HPP
-
-#include "view.hpp"
+#pragma once
 
 #include <cstddef>
 #include <cstdint>
@@ -18,51 +15,28 @@
 namespace cruft {
     ///////////////////////////////////////////////////////////////////////////
     /// round the pointer upwards to satisfy the provided alignment
-    template <typename T>
-    constexpr T*
-    align (T *_ptr, size_t alignment)
-    {
-        // we perform this as two steps to avoid unnecessarily incrementing when
-        // remainder is zero.
-        auto ptr = reinterpret_cast<uintptr_t> (_ptr);
-        if (ptr % alignment)
-            ptr += alignment - ptr % alignment;
-        return reinterpret_cast<T*> (ptr);
-    }
-
-
-    ///////////////////////////////////////////////////////////////////////////
-    template <typename ValueT>
-    constexpr cruft::view<ValueT*>
-    align (cruft::view<ValueT*> value, size_t alignment)
-    {
-        return {
-            align (value.begin (), alignment),
-            value.end ()
-        };
-    }
-
-
-    ///------------------------------------------------------------------------
-    /// round the pointer upwards to satisfy the provided alignment
     constexpr inline uintptr_t
-    align (uintptr_t ptr, size_t alignment)
+    align_up (uintptr_t ptr, size_t alignment)
     {
         // we perform this as two steps to avoid unnecessarily incrementing when
         // remainder is zero.
-        if (ptr % alignment)
-            ptr += alignment - ptr % alignment;
+        if (auto mod = ptr % alignment; mod)
+            ptr += alignment - mod;
         return ptr;
     }
 
 
-    ///------------------------------------------------------------------------
-    /// round the pointer upwards to the nearest valid alignment for T
+    ///////////////////////////////////////////////////////////////////////////
+    /// round the pointer upwards to satisfy the provided alignment
     template <typename T>
-    constexpr auto
-    align (T *t)
+    constexpr T*
+    align_up (T *_ptr, size_t alignment)
     {
-        return align (t, alignof (T));
+        // we perform this as two steps to avoid unnecessarily incrementing when
+        // remainder is zero.
+        return reinterpret_cast<T*>(
+            align_up (reinterpret_cast<uintptr_t> (_ptr), alignment)
+        );
     }
 
 
@@ -70,10 +44,37 @@ namespace cruft {
     /// round the pointer upwards to the nearest valid alignment for T
     template <typename T>
     constexpr auto
-    align (uintptr_t ptr)
+    align_up (T *t)
     {
-        return align (ptr, alignof (T));
+        return align_up (t, alignof (T));
+    }
+
+
+    ///------------------------------------------------------------------------
+    /// round the pointer upwards to the nearest valid alignment for T
+    template <typename T>
+    constexpr auto
+    align_up (uintptr_t ptr)
+    {
+        return align_up (ptr, alignof (T));
+    }
+
+
+    ///////////////////////////////////////////////////////////////////////////
+    constexpr inline uintptr_t
+    align_down (uintptr_t ptr, size_t alignment)
+    {
+        return ptr - ptr % alignment;
+    }
+
+
+    //-------------------------------------------------------------------------
+    template <typename T>
+    constexpr T*
+    align_down (T *ptr, size_t alignment)
+    {
+        return reinterpret_cast<T*> (
+            align_down (reinterpret_cast<uintptr_t> (ptr), alignment)
+        );
     }
 }
-
-#endif

test/alloc/aligned/foreign.cpp

@@ -12,7 +12,7 @@ main ()
 
     // ensure we have an base pointer that's off-by-one to a likely natural
     // system alignment
-    std::byte* base = cruft::align (
+    std::byte* base = cruft::align_up (
         std::data (buffer),
         alignof (std::max_align_t)
     ) + increment;