Typesafe align macros

src/arena.c

@@ -38,7 +38,7 @@ void arena_init(Arena *arena, const ArenaOptions *opts)
     MemoryBlock *block  = memoryblock_allocate(aligned_size, aligned_commit_size, page_size);
 
     arena->flags            = opts->flags;
-    arena->checkpoint_level = 0;
+    arena->temp_level = 0;
     arena->current          = block;
     arena->block_size       = aligned_size;
     arena->commit_size      = aligned_commit_size;
@@ -48,7 +48,7 @@ void arena_init(Arena *arena, const ArenaOptions *opts)
 void arena_free(Arena *arena)
 {
     MemoryBlock *block = arena->current;
-    Assert(arena->checkpoint_level == 0);
+    Assert(arena->temp_level == 0);
     while (block != NULL) {
         MemoryBlock *prev = block->prev;
         memory_free(block->base, block->size);
@@ -137,7 +137,7 @@ ATemp arena_temp_begin(Arena *arena)
     ATemp checkpoint = {};
     checkpoint.arena           = arena;
     checkpoint.total_offset    = arena_used(arena);
-    arena->checkpoint_level++;
+    arena->temp_level++;
 
     return checkpoint;
 }
@@ -145,9 +145,9 @@ ATemp arena_temp_begin(Arena *arena)
 void arena_temp_end(ATemp *checkpoint)
 {
     Arena *arena = checkpoint->arena;
-    Assert(arena->checkpoint_level > 0);
+    Assert(arena->temp_level > 0);
     arena_reset_to(arena, checkpoint->total_offset);
-    arena->checkpoint_level--;
+    arena->temp_level--;
 }
 
 void arena_reset(Arena *arena)

src/arena.h

@@ -27,7 +27,7 @@ struct Arena {
     U32 commit_size;    // requested commit size
     U32 page_size;      // cached page size
     ArenaFlags flags;
-    S32 checkpoint_level;
+    S32 temp_level;
 };
 
 typedef struct ATemp ATemp;

src/base_core.h

@@ -104,12 +104,43 @@ typedef unsigned __int128 U128;
     (const type *)((const void *)(const unsigned char *)__mptr - offsetof(const type, member));                     \
   })
 
-// align needs to be pow2
-#define AlignUp(val, align)     (((val) + (align) - 1UL) & ~((align) - 1UL))
-#define AlignDown(val, align)   ((val) & ~((align) - 1UL))
-#define IsPow2(x)                   ((x) && !((x) & ((x) - 1UL)))
-#define IsPow2OrZero(x)             (!((x) & ((x) - 1UL)))
-#define IsAlignedTo(x, align)           (IsPow2(align) && !((x) & ((align) - 1UL)))
+// `align` must be a power of two.
+//
+// These keep the result in the *same integer type as the first argument*
+#define AlignUp(val, align)                                                \
+  ({                                                                       \
+    __typeof__(val) AlignUp_v_ = (val);                                    \
+    __typeof__(val) AlignUp_a_ = (__typeof__(val))(align);                 \
+    (__typeof__(val))((AlignUp_v_ + (AlignUp_a_ - 1)) &                    \
+                      ~(__typeof__(val))(AlignUp_a_ - 1));                 \
+  })
+
+#define AlignDown(val, align)                                              \
+  ({                                                                       \
+    __typeof__(val) AlignDown_v_ = (val);                                  \
+    __typeof__(val) AlignDown_a_ = (__typeof__(val))(align);               \
+    (__typeof__(val))(AlignDown_v_ & ~(__typeof__(val))(AlignDown_a_ - 1));\
+  })
+
+#define IsPow2(x)                                                          \
+  ({                                                                       \
+    __typeof__(x) IsPow2_x_ = (x);                                         \
+    IsPow2_x_ && !(IsPow2_x_ & (__typeof__(x))(IsPow2_x_ - 1));            \
+  })
+
+#define IsPow2OrZero(x)                                                    \
+  ({                                                                       \
+    __typeof__(x) IsPow2OrZero_x_ = (x);                                   \
+    !(IsPow2OrZero_x_ & (__typeof__(x))(IsPow2OrZero_x_ - 1));             \
+  })
+
+#define IsAlignedTo(x, align)                                              \
+  ({                                                                       \
+    __typeof__(x) IsAlignedTo_x_ = (x);                                    \
+    __typeof__(x) IsAlignedTo_a_ = (__typeof__(x))(align);                 \
+    IsPow2(IsAlignedTo_a_) &&                                              \
+        !(IsAlignedTo_x_ & (__typeof__(x))(IsAlignedTo_a_ - 1));           \
+  })
 
 #define GetBit(val, idx) (((val) >> (idx)) & 1)
 // Get n_bits starting at idx going left

src/mini_arena.h

@@ -6,9 +6,9 @@
 typedef struct MArena MArena;
 struct MArena {
     U8 *base;         // start of buffer
-    U32 first_free;   // next alloc point
+    U32 first_free;
     U32 size;
-    S32 checkpoint_level;  // level of marena_temp_begin nesting
+    S32 temp_level;  // level of marena_temp_begin nesting
 };
 
 typedef struct MTemp MTemp;
@@ -18,7 +18,7 @@ struct MTemp {
 };
 
 #define MARENA_STATIC_INITIALIZER(data) MARENA_INITIALIZER((data), sizeof(data))
-#define MARENA_INITIALIZER(data, size_) {.base = (data), .first_free = 0, .size = (U32)size_, .checkpoint_level = 0}
+#define MARENA_INITIALIZER(data, size_) {.base = (data), .first_free = 0, .size = (U32)size_, .temp_level = 0}
 #define MARENA_DEFINE(var_name, size, alignment_)  \
     struct { \
         _Alignas(alignment_) U8 memory[size];\
@@ -41,7 +41,7 @@ static INLINE MTemp marena_temp_begin(MArena *arena)
 
     checkpoint.arena  = arena;
     checkpoint.offset = arena->first_free;
-    arena->checkpoint_level++;
+    arena->temp_level++;
 
     return checkpoint;
 }
@@ -49,13 +49,15 @@ static INLINE MTemp marena_temp_begin(MArena *arena)
 static INLINE void marena_temp_end(MTemp *state)
 {
     MArena *arena = state->arena;
-    Assert(arena->checkpoint_level > 0);
+    Assert(arena->temp_level > 0);
     arena->first_free = state->offset;
-    arena->checkpoint_level--;
+    arena->temp_level--;
 }
 
-#define marena_push_type(allocator, type_) marenaalloc_aligned((allocator), sizeof(type_), _Alignof(type_))
-#define marena_push_array(allocator, type_, nr_elements_) marenaalloc_aligned((allocator), (nr_elements_) * (U32)sizeof(type_), _Alignof(type_))
+#define marena_push_type(allocator, type_)\
+        marenaalloc_aligned((allocator), sizeof(type_), _Alignof(type_))
+#define marena_push_array(allocator, type_, nr_elements_)\
+        marenaalloc_aligned((allocator), (nr_elements_) * (U32)sizeof(type_), _Alignof(type_))
 
 
 static INLINE void *marena_push(MArena *arena, U32 size)
@@ -74,7 +76,7 @@ static INLINE void *maren_push_aligned(MArena *arena, U32 size, U32 align)
     Assert(IsPow2(align));
 
     U32 aligned = AlignUp(arena->first_free, align);
-    if (aligned < arena->first_free) { // align wrapped
+    if (aligned < arena->first_free) { // aligned wrapped around
         return NULL;
     }