Formatting issue

src/arena.c

@@ -5,49 +5,50 @@
 
 static MemoryBlock *memoryblock_allocate(U32 size, U32 commit_size, U32 page_size)
 {
-    U32 aligned_size        = AlignUpPow2(size, page_size);
+    Assert(IsAlignedTo(size, page_size));
-    U32 aligned_commit_size = AlignUpPow2(commit_size, page_size);
+    Assert(IsAlignedTo(commit_size, page_size));
 
-    MemoryBlock *block = memory_reserve(aligned_size);
+    MemoryBlock *block = memory_reserve(size);
     Assert(block != NULL);
-    memory_commit(block, aligned_commit_size);
+    memory_commit(block, commit_size);
+
+    ASAN_POISON_MEMORY_REGION(block, size);
+    ASAN_UNPOISON_MEMORY_REGION(block, MemoryBlock_Header_Size);
 
     block->base          = (U8 *)block;
-    block->size          = aligned_size;
+    block->size          = size;
-    block->pos           = MemoryBlock_Header_Size;
+    block->first_free    = MemoryBlock_Header_Size;
-    block->base_pos      = 0;
+    block->arena_offset  = 0;
     block->prev          = NULL;
-    block->committed_end = aligned_commit_size;
+    block->committed_end = commit_size;
-
-    ASAN_POISON_MEMORY_REGION(block->base, block->size);
-    ASAN_UNPOISON_MEMORY_REGION(block, MemoryBlock_Header_Size);
     return block;
 }
 
-void arena_init(Arena *arena, const ArenaParams *params)
+void arena_init(Arena *arena, const ArenaOptions *opts)
 {
     U32 page_size = platform_page_size();
-    Assert(params->size > MemoryBlock_Header_Size);
+    Assert(opts->size > MemoryBlock_Header_Size);
-    Assert(params->size < (U32_Max -  page_size)); // Reserving last piece so our math doesn't overflow
+    Assert(opts->size < (U32_Max -  page_size)); // Reserving last piece so our math doesn't overflow
-    Assert(params->commit_size > 0);
+    Assert(opts->commit_size > 0);
-    Assert(params->commit_size <= params->size);
 
+    U32 aligned_commit_size = AlignUp(opts->commit_size, page_size);
+    U32 aligned_size        = AlignUp(opts->size, page_size);
+    Assert(aligned_commit_size <= aligned_size);
 
-    MemoryBlock *block = memoryblock_allocate(params->size, params->commit_size, page_size);
+    MemoryBlock *block  = memoryblock_allocate(aligned_size, aligned_commit_size, page_size);
 
-    arena->flags            = params->flags;
+    arena->flags            = opts->flags;
-    arena->checkpoint_level = 0;
+    arena->temp_level = 0;
     arena->current          = block;
-    arena->block_size       = params->size;
+    arena->block_size       = aligned_size;
-    arena->commit_size      = params->commit_size;
+    arena->commit_size      = aligned_commit_size;
     arena->page_size        = page_size;
-
 }
 
 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);
@@ -58,29 +59,32 @@ void arena_free(Arena *arena)
 
 void *arena_push(Arena *arena, U32 size, U32 align)
 {
-    Assert(size < (U32_Max - platform_page_size()));
     Assert(IsPow2(align));
 
+
     MemoryBlock *block = arena->current;
-    U32 start_pos = AlignUpPow2(block->pos, align);  // might align past block->size, handled in below check
+    U32 start_pos = AlignUp(block->first_free, align);  // might align past block->size, handled in below check
     U32 available = block->size - start_pos;
 
     if (start_pos > block->size || available < size) {
-        U32 block_size = arena->block_size; // original user requested size
+        U32 pad = AlignUp(MemoryBlock_Header_Size, align);
+        Assert(size <= (U32_Max - arena->page_size) - pad);
+        U32 needed = pad + size;
+        U32 new_block_size = arena->block_size;
         U32 new_commit_size = arena->commit_size;
-        if (size > block_size - MemoryBlock_Header_Size) {
+        if (needed > new_block_size) {
-            block_size = AlignUpPow2(size + MemoryBlock_Header_Size,align);
+            new_block_size = AlignUp(needed, arena->page_size);
-            new_commit_size = block_size;
+            new_commit_size = new_block_size;
         }
 
-        MemoryBlock *new_block  = memoryblock_allocate(block_size, new_commit_size, arena->page_size);
+        MemoryBlock *new_block = memoryblock_allocate(new_block_size, new_commit_size, arena->page_size);
-        // base_pos tracks the virtual absolute position within an arena
+        // arena_offset tracks the virtual absolute position within an arena
         // This is not a contiguous space, we use it to free blocks when popping the arena
-        new_block->base_pos     = block->base_pos + block->size;
+        new_block->arena_offset = block->arena_offset + block->size;
         new_block->prev         = block;
         arena->current          = new_block;
         block                   = new_block;
-        start_pos               = AlignUpPow2(block->pos, align);
+        start_pos               = AlignUp(block->first_free, align);
     }
 
     U32 end_pos = start_pos + size;
@@ -89,7 +93,7 @@ void *arena_push(Arena *arena, U32 size, U32 align)
     U8 *mem = &block->base[start_pos];
     if (block->committed_end < end_pos) {
         // Commit more memory
-        U32 aligned_end_pos   = AlignUpPow2(start_pos + size, arena->page_size);
+        U32 aligned_end_pos   = AlignUp(start_pos + size, arena->page_size);
         U32 aligned_size      = RoundUpToMultiple(aligned_end_pos - block->committed_end, arena->commit_size);
         aligned_size = Min(aligned_size, block->size - block->committed_end);
 
@@ -97,30 +101,36 @@ void *arena_push(Arena *arena, U32 size, U32 align)
         block->committed_end  += aligned_size;
         Assert(block->committed_end <= block->size);
     }
-    block->pos  = end_pos;
+    block->first_free  = end_pos;
 
     ASAN_UNPOISON_MEMORY_REGION(mem, size);
     return mem;
 }
 
-void arena_pop_to(Arena *arena, U64 abs_pos)
+void arena_reset_to(Arena *arena, U64 total_offset)
 {
     MemoryBlock *block = arena->current;
-    abs_pos = Max(MemoryBlock_Header_Size, abs_pos);
+    total_offset = Max(MemoryBlock_Header_Size, total_offset);
     while (block) {
         MemoryBlock *prev = block->prev;
 
-        if (block->base_pos >= abs_pos) {
+        if (block->arena_offset >= total_offset) {
-            ASAN_UNPOISON_MEMORY_REGION(block->base, block->size);
+            ASAN_UNPOISON_MEMORY_REGION(block->base, block->committed_end);
             memory_free(block->base, block->size);
             arena->current = prev;
         } else {
-            U64 new_pos = abs_pos - block->base_pos;
+            U64 new_pos = total_offset - block->arena_offset;
             new_pos = Max(MemoryBlock_Header_Size, new_pos);
-            // Disallow arbirary pops to positions that previously were not commited.
+            // Disallow arbitrary pops to positions that previously were not commited.
             Assert(new_pos <= block->committed_end);
-            block->pos = new_pos;
+            Assert(new_pos <= block->size);
-            ASAN_POISON_MEMORY_REGION(&block->base[block->pos], memoryblock_available(block));
+            block->first_free = new_pos;
+            ASAN_POISON_MEMORY_REGION(&block->base[block->first_free], memoryblock_available(block));
+
+            if ((arena->flags & ArenaFlag_NoDecommit) == 0) {
+                arena_trim(arena);
+            }
+
             break;
         }
 
@@ -128,25 +138,39 @@ void arena_pop_to(Arena *arena, U64 abs_pos)
     }
 }
 
-ArenaCheckpoint arena_temp_begin(Arena *arena)
+void arena_trim(Arena *arena)
 {
-    ArenaCheckpoint checkpoint = {};
+    MemoryBlock *block = arena->current;
+    U32 aligned_pos = RoundUpToMultiple(block->first_free, arena->commit_size);
+    if (aligned_pos < block->committed_end) {
+        void *trim_start = &block->base[aligned_pos];
+        // Note(nos): Should we unpoision ?
+        //ASAN_UNPOISON_MEMORY_REGION(trim_start, block->committed_end);
+        memory_decommit(trim_start, block->committed_end - aligned_pos);
+        block->committed_end = aligned_pos;
+    }
+}
+
+ATemp arena_temp_begin(Arena *arena)
+{
+    ATemp checkpoint = {};
     checkpoint.arena           = arena;
-    checkpoint.absolute_pos    = arena_used(arena);
+    checkpoint.total_offset    = arena_used(arena);
-    arena->checkpoint_level++;
+    arena->temp_level++;
 
     return checkpoint;
 }
 
-void arena_temp_end(ArenaCheckpoint *checkpoint)
+void arena_temp_end(ATemp *checkpoint)
 {
     Arena *arena = checkpoint->arena;
-    Assert(arena->checkpoint_level > 0);
+    Assert(arena->temp_level > 0);
-    arena_pop_to(arena, checkpoint->absolute_pos);
+    arena_reset_to(arena, checkpoint->total_offset);
-    arena->checkpoint_level--;
+    arena->temp_level--;
 }
 
 void arena_reset(Arena *arena)
 {
-    arena_pop_to(arena, 0);
+    arena_reset_to(arena, 0);
 }
+

src/arena.h

@@ -2,10 +2,12 @@
 #include "base_core.h"
 
 
-typedef U32 ArenaFlags; // no flags defined yet
+typedef U32 ArenaFlags;
-
+typedef struct ArenaOptions ArenaOptions;
-typedef struct ArenaParams ArenaParams;
+enum {
-struct ArenaParams {
+    ArenaFlag_NoDecommit, // arena_ temp_end/reset/reset_to doesn't decommit memory
+};
+struct ArenaOptions {
     U32 size;
     U32 commit_size;
     ArenaFlags flags; // No flags defined yet
@@ -15,8 +17,8 @@ typedef struct MemoryBlock MemoryBlock;
 struct MemoryBlock {
     U8 *base;
     U32 size;           // Block size, page aligned
-    U32 pos;            // start of next allocation
+    U32 first_free;     // start of next allocation
-    U64 base_pos;       // absolute position of base relative to the first linked arena
+    U64 arena_offset;   // absolute offset of base relative to the first linked arena
     U32 committed_end;  // end of committed region. Will be page aligned
     MemoryBlock *prev;
 };
@@ -28,23 +30,23 @@ struct Arena {
     U32 commit_size;    // requested commit size
     U32 page_size;      // cached page size
     ArenaFlags flags;
-    S32 checkpoint_level;
+    S32 temp_level;
 };
 
-typedef struct ArenaCheckpoint ArenaCheckpoint;
+typedef struct ATemp ATemp;
-struct ArenaCheckpoint {
+struct ATemp {
     Arena *arena;
-    U64 absolute_pos;
+    U64 total_offset;
 };
-#ifndef ArenaParams_Default
+#ifndef ArenaOptions_Default
-#define ArenaParams_Default { .size = MB(32), .commit_size = KB(64) }
+#define ArenaOptions_Default ((ArenaOptions){ .size = MB(32), .commit_size = KB(64) })
 #endif
 
 StaticAssert(sizeof(MemoryBlock) <= 64);
 // Try keep start of user memory at a cacheline
 #define MemoryBlock_Header_Size 64u
 
-void arena_init(Arena *arena, const ArenaParams *params);
+void arena_init(Arena *arena, const ArenaOptions *params);
 void arena_free(Arena *arena);
 void *arena_push(Arena *arena, U32 size, U32 align);
 
@@ -52,18 +54,47 @@ void *arena_push(Arena *arena, U32 size, U32 align);
 // Invalid for arrays > U32
 #define arena_push_array_of(arena, type, len) arena_push(arena, (U32) (sizeof(type) * (len)), alignof(type))
 
-ArenaCheckpoint arena_temp_begin(Arena *arena);
+void arena_trim(Arena *arena);
-void arena_temp_end(ArenaCheckpoint *checkpoint);
+
-void arena_pop_to(Arena *arena, U64 abs_pos);
+ATemp arena_temp_begin(Arena *arena);
+void arena_temp_end(ATemp *checkpoint);
+void arena_reset_to(Arena *arena, U64 total_offset);
 void arena_reset(Arena *arena);
 
 static INLINE U32 memoryblock_available(const MemoryBlock *block)
 {
-    return block->size - block->pos;
+    return block->size - block->first_free;
 }
 
 static INLINE U64 arena_used(const Arena *arena)
 {
     const MemoryBlock *block = arena->current;
-    return block->base_pos + block->pos;
+    return block->arena_offset + block->first_free;
+}
+
+
+static INLINE void *arena_allocator_func(Allocator *allocator, AllocOperation operation , void *memory, U32 size, U32 align)
+{
+    switch (operation) {
+        case Alloc_Op_Aligned:
+            return arena_push(allocator->data, size, align);
+
+        case Alloc_Op_Free: // can't free from  an marena
+            return NULL;
+
+        case Alloc_Op_Free_All:
+            arena_free(allocator->data);
+            return NULL;
+    }
+
+    Assert(false);
+}
+
+static INLINE Allocator arena_allocator(Arena *arena)
+{
+    Allocator allocator = {};
+    allocator.op_func_ptr = arena_allocator_func;
+    allocator.data = arena;
+
+    return allocator;
 }

src/base_core.h

@@ -104,11 +104,43 @@ typedef unsigned __int128 U128;
     (const type *)((const void *)(const unsigned char *)__mptr - offsetof(const type, member));                     \
   })
 
-#define AlignUpPow2(val, align)     (((val) + (align) - 1UL) & ~((align) - 1UL))
+// `align` must be a power of two.
-#define AlignDownPow2(val, align)   ((val) & ~((align) - 1UL))
+//
-#define IsPow2(x)                   ((x) && !((x) & ((x) - 1UL)))
+// These keep the result in the *same integer type as the first argument*
-#define IsPow2OrZero(x)             (!((x) & ((x) - 1UL)))
+#define AlignUp(val, align)                                                \
-#define IsAlignedTo(x, y)           (IsPow2(y) && !((x) & ((y) - 1UL)))
+  ({                                                                       \
+    __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
@@ -145,7 +177,8 @@ typedef unsigned __int128 U128;
 #define CeilDiv(x, y) (((x) + ((y) - 1)) / (y))
 
 /**
- * Round x up to nearest multiple of y
+ * Round x up to nearest multiple of y:
+ * (((x) + (y) - 1) - (((x) + (y) - 1) % (y)))
  * e.g. RoundUp(30,48) == 48
  * e.g. RoundUp(49,48) == 96
  *
@@ -153,7 +186,15 @@ typedef unsigned __int128 U128;
  * @param y denominator
  * @return x rounded up to nearest multiple of y
  */
-#define RoundUpToMultiple(x, y) (CeilDiv((x), (y)) * (y))
+#define RoundUpToMultiple(x, y)       \
+({                                    \
+    __typeof__(x) _x   = (x);         \
+    __typeof__(y) _y   = (y);         \
+    Assert(_y         != 0);          \
+    __typeof__(x) _tmp = _x + _y - 1; \
+    _tmp - _tmp % _y;                 \
+})
+
 
 /**
  * Round x down to nearest multiple of y
@@ -303,6 +344,46 @@ static INLINE U64 SaturatingMult64(U64 a, U64 b)
     return SaturatingMult(a, b, U64, U64_Max);
 }
 
+// Allocators
+typedef enum AllocOperation AllocOperation;
+enum AllocOperation {
+    Alloc_Op_Aligned = 1,
+    Alloc_Op_Free,
+    Alloc_Op_Free_All,
+};
+
+typedef struct Allocator Allocator;
+typedef void *(*AllocOpFunc)(Allocator *allocator, AllocOperation operation, void *memory, U32 size, U32 align);
+struct Allocator {
+    AllocOpFunc op_func_ptr;
+    void *data;
+};
+
+static INLINE void *allocator_alloc_aligned(Allocator *allocator, U32 size, U32 align)
+{
+    return allocator->op_func_ptr(allocator, Alloc_Op_Aligned, NULL, size, align);
+}
+
+static INLINE void allocator_free(Allocator *allocator, void *memory)
+{
+    allocator->op_func_ptr(allocator, Alloc_Op_Free, memory, 0, 0);
+}
+
+static INLINE void  allocator_free_all(Allocator *allocator)
+{
+    allocator->op_func_ptr(allocator, Alloc_Op_Free_All, NULL, 0, 0);
+}
+
+
+#define allocator_push_type(allocator, type_)\
+    (allocator)->op_func_ptr((allocator), Alloc_Op_Aligned, NULL, sizeof(type_), _Alignof(type_))
+
+#define allocator_push_array(allocator, type_, nr_elements)\
+    (allocator)->op_func_ptr((allocator), Alloc_Op_Aligned, NULL, sizeof(type_) * (nr_elements), _Alignof(type_) )
+
+#define allocator_push(allocator, size, align)\
+    (allocator)->op_func_ptr((allocator), Alloc_Op_Aligned, NULL, size, align)
+
 // address-sanitizer helpers (-fsanitize=address)
 #ifdef USE_ASAN
 #include <sanitizer/asan_interface.h>

src/main.c

@@ -1,8 +1,12 @@
 #include "base_core.h"
 #include "arena.h"
+#include "mini_arena.h"
+#include "platform.h"
+#include "pool.h"
 #include <stdio.h>
 #include <stdlib.h>
 
+
 void arena_dump(const Arena *arena)
 {
     return;
@@ -12,8 +16,8 @@ void arena_dump(const Arena *arena)
         puts("-----Arena-----");
         printf("base:        %p\n", block->base);
         printf("size:        %u\n", block->size);
-        printf("pos:         %u\n", block->pos);
+        printf("first_free:         %u\n", block->first_free);
-        printf("base_pos:    %lu\n",block->base_pos);
+        printf("total_used:    %lu\n",block->arena_offset);
         printf("prev: %p\n", block->prev);
         puts("-----Arena  end-");
         block = block->prev;
@@ -22,7 +26,7 @@ void arena_dump(const Arena *arena)
 static void arena_test_1(void)
 {
     TRACEF("\n");
-    ArenaParams arena_params = {};
+    ArenaOptions arena_params = {};
     U32 arena_size = MB(1) + MemoryBlock_Header_Size;
     U32 commit_size = KB(8);
     arena_params.size = arena_size;
@@ -50,9 +54,9 @@ static void arena_test_2(void)
 {
     TRACEF("\n");
 
-    ArenaParams arena_params = {};
+    ArenaOptions arena_params = {};
-    U32 arena_size = MB(1) + MemoryBlock_Header_Size;
+    U32 arena_size = MB(3) + MemoryBlock_Header_Size;
-    U32 commit_size = KB(16);
+    U32 commit_size = KB(72);
     U32 push_size = KB(32);
     arena_params.size = arena_size;
     arena_params.commit_size = commit_size;
@@ -65,8 +69,8 @@ static void arena_test_2(void)
     printf("Allocated ptr %p\n", ptr);
 
     arena_dump(&arena);
-    ArenaCheckpoint checkpoint = arena_temp_begin(&arena);
+    ATemp checkpoint = arena_temp_begin(&arena);
-    ptr = arena_push(&arena, MB(2), 8);
+    ptr = arena_push(&arena, MB(4)+3, 8);
     MemoryZero(ptr, MB(2));
 
     ptr = arena_push(&arena, commit_size * 3, 8);
@@ -74,14 +78,14 @@ static void arena_test_2(void)
     ptr = arena_push(&arena, commit_size , 8);
     MemoryZero(ptr, commit_size  );
 
-    ArenaCheckpoint checkpoint2 = arena_temp_begin(&arena);
+    ATemp checkpoint2 = arena_temp_begin(&arena);
     ptr = arena_push(&arena, 64, 8);
     MemoryZero(ptr, 64);
 
     arena_temp_end(&checkpoint2);
 
     arena_temp_end(&checkpoint);
-    arena_pop_to(&arena, 1088);
+    arena_reset_to(&arena, 1088);
     arena_dump(&arena);
     ptr = arena_push(&arena, 1, KB(16));
     ((U8*)ptr)[0] = 0x37;
@@ -89,11 +93,13 @@ static void arena_test_2(void)
     ((U8*)ptr)[0] = 0x73;
     ptr = arena_push(&arena, 0, KB(4));
     //((U8*)ptr)[0] = 0x73;
-    arena_pop_to(&arena, 1089);
+  //  arena_reset_to(&arena, 1089);
     arena_dump(&arena);
-    arena_pop_to(&arena, 0);
+    arena_reset_to(&arena, 0);
-    ptr = arena_push(&arena, MB(1), 8);
+    for (U64 i = 0; i < MB(4); i++) {
-    MemoryZero(ptr, MB(1));
+        ptr = arena_push(&arena,  3, 1);
+        MemoryZero(ptr, 3);
+    }
     arena_free(&arena);
 }
 
@@ -101,7 +107,7 @@ static void arena_test_3(void)
 {
     TRACEF("\n");
 
-    ArenaParams arena_params = {};
+    ArenaOptions arena_params = {};
     U32 arena_size = KB(97) + MemoryBlock_Header_Size;
     U32 commit_size = KB(97);
     arena_params.size = arena_size;
@@ -120,9 +126,303 @@ static void arena_test_3(void)
     arena_free(&arena);
 }
 
+// Exercises the alignment-padding edge case: a fresh block has first_free at
+// MemoryBlock_Header_Size (64), so a large alignment pushes the user pointer
+// well past the header. Requesting (block_size - 64) bytes with page alignment
+// previously tripped the end_pos <= block->size assert because the alignment
+// gap was not accounted for. After the fix this should allocate a larger block.
+static void arena_test_4(void)
+{
+    TRACEF("\n");
+
+    U32 page_size = platform_page_size();
+    ArenaOptions arena_params = {};
+    U32 arena_size  = MB(1) + MemoryBlock_Header_Size;
+    U32 commit_size = KB(64);
+    arena_params.size = arena_size;
+    arena_params.commit_size = commit_size;
+    Arena arena;
+    arena_init(&arena, &arena_params);
+
+    // block_size is the page-aligned arena_size. Request nearly the whole block
+    // but with page alignment, so the alignment gap (a full page) forces a grow.
+    U32 block_size = arena.block_size;
+    U32 push_size  = block_size - MemoryBlock_Header_Size;
+
+    void *ptr = arena_push(&arena, push_size, page_size);
+    Assert(IsAlignedTo((uintptr_t)ptr, page_size));
+    MemoryZero(ptr, push_size);
+    printf("test_4: allocated %u bytes page-aligned at %p\n", push_size, ptr);
+    arena_dump(&arena);
+
+    // A second page-aligned push to make sure the cursor math still holds.
+    ptr = arena_push(&arena, page_size, page_size);
+    Assert(IsAlignedTo((uintptr_t)ptr, page_size));
+    MemoryZero(ptr, page_size);
+    printf("test_4: allocated %u bytes page-aligned at %p\n", page_size, ptr);
+
+    arena_free(&arena);
+}
+
+static void arena_test_allocator_interface(void)
+{
+    TRACEF("\n");
+
+    U32 page_size = platform_page_size();
+    ArenaOptions arena_params = {};
+    U32 arena_size  = MB(1) + MemoryBlock_Header_Size;
+    U32 commit_size = KB(64);
+    arena_params.size = arena_size;
+    arena_params.commit_size = commit_size;
+    Arena arena;
+    arena_init(&arena, &arena_params);
+    Allocator allocator = arena_allocator(&arena);
+
+    // block_size is the page-aligned arena_size. Request nearly the whole block
+    // but with page alignment, so the alignment gap (a full page) forces a grow.
+    U32 block_size = arena.block_size;
+    U32 push_size  = block_size - MemoryBlock_Header_Size;
+
+    void *ptr = allocator_push(&allocator, push_size, page_size);
+    Assert(IsAlignedTo((uintptr_t)ptr, page_size));
+    MemoryZero(ptr, push_size);
+    printf("test_4: allocated %u bytes page-aligned at %p\n", push_size, ptr);
+    arena_dump(&arena);
+
+    // A second page-aligned push to make sure the cursor math still holds.
+    ptr = allocator_push(&allocator, page_size, page_size);
+    Assert(IsAlignedTo((uintptr_t)ptr, page_size));
+    MemoryZero(ptr, page_size);
+    printf("test_4: allocated %u bytes page-aligned at %p\n", page_size, ptr);
+
+    allocator_free_all(&allocator);
+    arena_free(&arena);
+
+}
+
+static void arena_test_decommit(void)
+{
+    TRACEF("\n");
+
+    U32 page_size = platform_page_size();
+    ArenaOptions arena_params = {};
+    U32 arena_size  = MB(1) + MemoryBlock_Header_Size;
+    U32 commit_size = KB(64);
+    arena_params.size = arena_size;
+    arena_params.commit_size = commit_size;
+    Arena arena;
+    arena_init(&arena, &arena_params);
+    void *ptr = arena_push(&arena, commit_size * 10, 8);
+    MemoryZero(ptr, commit_size * 10);
+    arena_reset(&arena);
+
+    void *pre_ptr = arena_push(&arena, 5, 4);
+
+    ATemp tmp = arena_temp_begin(&arena);
+    ptr = arena_push(&arena, commit_size * 2 + 13, 8);
+    MemoryZero(ptr, commit_size * 2 + 13);
+    arena_temp_end(&tmp);
+    MemoryZero(pre_ptr, 5);
+
+    arena_free(&arena);
+}
+
+void miniarena_test1(void)
+{
+    TRACEF("\n");
+
+    #define  arena_size  4096
+    MARENA_DEFINE(arena, arena_size, 8);
+    int i;
+    for (i = 0; ; i++) {
+        void *ptr = marena_push(&arena, 1);
+        if (ptr == NULL) {
+            break;
+        }
+    }
+
+    printf("miniarena_test1,size %u pushed %d bytes first_free %u\n", arena.size, i, arena.first_free);
+    marena_reset(&arena);
+    MTemp checkpoint = marena_temp_begin(&arena);
+
+    void *ptr = marena_push(&arena, arena_size);
+    Assert(ptr != NULL);
+    Assert(arena.first_free == arena_size);
+    MemoryZero(ptr, arena_size);
+    marena_temp_end(&checkpoint);
+    Assert(arena.first_free == 0);
+    U32 *val = marena_push_type(&arena, U32);
+    *val = 0xa0b0c0d0;
+    printf("marena val 0x%x\n", *val);
+
+    printf("miniarena_test1,size %u bytes first_free %u\n", arena.size, arena.first_free);
+    Assert(arena.first_free == sizeof(U32));
+}
+
+typedef struct PoolTest PoolTest;
+struct PoolTest{
+    U32 n;
+    PoolTest *next;
+    char name[12];
+};
+
+void apool_test(void)
+{
+    TRACEF("\n");
+
+    Arena arena;
+    arena_init(&arena, &ArenaOptions_Default);
+    Allocator allocator = arena_allocator(&arena);
+    APool *pool = apool_create_ex(&allocator, 16, sizeof(PoolTest), alignof(PoolTest));
+    PoolTest *list = NULL;
+    for (U32 i = 0; i < U32_Max; i++) {
+        PoolTest *pt = apool_alloc(pool);
+        if (pt == NULL){
+            break;
+        }
+        pt->n = i;
+        pt->next = list;
+        list = pt;
+    }
+    for (PoolTest *p = list; p; p = p->next){
+        printf("Pooltest %u\n",p->n);
+    }
+
+    PoolTest *next;
+    U32 count = 0;
+    for (PoolTest *p = list; count < 7 && p; p = next){
+        count++;
+        next = p->next;
+        printf("Pooltest freeing %u\n",p->n);
+        apool_free(pool, p);
+    }
+    list = NULL;
+    for (U32 i = 0; i < U32_Max; i++) {
+        PoolTest *pt = apool_alloc(pool);
+        if (pt == NULL){
+            break;
+        }
+        pt->n = i;
+        pt->next = list;
+        list = pt;
+    }
+    for (PoolTest *p = list; p; p = p->next){
+        printf("Pooltest %u\n",p->n);
+    }
+    allocator_free_all(&allocator);
+    arena_free(&arena);
+}
+
+void apool_test_miniarena(void)
+{
+    TRACEF("\n");
+
+    MArena arena;
+    U8 data[4096];
+    marena_init(&arena, data, sizeof data);
+    Allocator allocator = marena_allocator(&arena);
+    APool *pool = apool_create_ex(&allocator, 16, sizeof(PoolTest), alignof(PoolTest));
+    PoolTest *list = NULL;
+    for (U32 i = 0; i < U32_Max; i++) {
+        PoolTest *pt = apool_alloc(pool);
+        if (pt == NULL){
+            break;
+        }
+        pt->n = i;
+        pt->next = list;
+        list = pt;
+    }
+    for (PoolTest *p = list; p; p = p->next){
+        printf("Pooltest %u\n",p->n);
+    }
+
+    PoolTest *next;
+    U32 count = 0;
+    for (PoolTest *p = list; count < 7 && p; p = next){
+        count++;
+        next = p->next;
+        printf("Pooltest freeing %u\n",p->n);
+        apool_free(pool, p);
+    }
+    list = NULL;
+    for (U32 i = 0; i < U32_Max; i++) {
+        PoolTest *pt = apool_alloc(pool);
+        if (pt == NULL){
+            break;
+        }
+        pt->n = i;
+        pt->next = list;
+        list = pt;
+    }
+    for (PoolTest *p = list; p; p = p->next){
+        printf("Pooltest %u\n",p->n);
+    }
+    allocator_free_all(&allocator);
+}
+
+
+void apool_test_autogrow(void)
+{
+    TRACEF("\n");
+
+    Arena arena;
+    arena_init(&arena, &ArenaOptions_Default);
+    Allocator allocator = arena_allocator(&arena);
+
+    APool *pool = apool_create(&allocator, APOOL_AUTOGROW, PoolTest);
+    PoolTest *list = NULL;
+    for (U32 i = 0; i < 4; i++) {
+        PoolTest *pt = apool_alloc(pool);
+        if (pt == NULL){
+            break;
+        }
+        pt->n = i;
+        pt->next = list;
+        list = pt;
+    }
+    for (PoolTest *p = list; p; p = p->next){
+        printf("Pooltest %u\n",p->n);
+    }
+
+    PoolTest *next;
+    U32 count = 0;
+    for (PoolTest *p = list; count < 3 && p; p = next){
+        count++;
+        next = p->next;
+        printf("Pooltest freeing %u\n",p->n);
+        apool_free(pool, p);
+    }
+    list = NULL;
+    for (U32 i = 0; i < 5; i++) {
+        PoolTest *pt = apool_alloc(pool);
+        if (pt == NULL){
+            break;
+        }
+        pt->n = i;
+        pt->next = list;
+        list = pt;
+    }
+    for (PoolTest *p = list; p; p = p->next){
+        printf("Pooltest %u\n",p->n);
+    }
+
+    allocator_free_all(&allocator);
+    arena_free(&arena);
+
+}
+
 int main(int argc, char *argv[])
 {
     arena_test_1();
     arena_test_2();
     arena_test_3();
+    arena_test_4();
+    arena_test_decommit();
+    arena_test_allocator_interface();
+    miniarena_test1();
+    apool_test();
+    apool_test_autogrow();
+    apool_test_miniarena();
+
 }
+

src/mini_arena.h

@@ -0,0 +1,121 @@
+#pragma once
+#include "base_core.h"
+
+// Mini Arena for arena allocations from a supplied buffer
+
+typedef struct MArena MArena;
+struct MArena {
+    U8 *base;         // start of buffer
+    U32 first_free;
+    U32 size;
+    S32 temp_level;  // level of marena_temp_begin nesting
+};
+
+typedef struct MTemp MTemp;
+struct MTemp {
+    U32 offset;
+    MArena *arena;
+};
+
+#define MARENA_STATIC_INITIALIZER(data) MARENA_INITIALIZER((data), sizeof(data))
+#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];\
+    } var_name##_marena_memory; \
+    MArena var_name = MARENA_STATIC_INITIALIZER(var_name##_marena_memory.memory)
+
+
+
+static INLINE void marena_init(MArena *arena, void *memory, U32 size)
+{
+    Assert(memory != NULL);
+    arena->base       = (U8 *)memory;
+    arena->first_free = 0;
+    arena->size       = size;
+}
+
+static INLINE MTemp marena_temp_begin(MArena *arena)
+{
+    MTemp checkpoint = {};
+
+    checkpoint.arena  = arena;
+    checkpoint.offset = arena->first_free;
+    arena->temp_level++;
+
+    return checkpoint;
+}
+
+static INLINE void marena_temp_end(MTemp *state)
+{
+    MArena *arena = state->arena;
+    Assert(arena->temp_level > 0);
+    arena->first_free = state->offset;
+    arena->temp_level--;
+}
+
+static INLINE void *marena_push(MArena *arena, U32 size)
+{
+    if (size > arena->size - arena->first_free) {
+        return NULL;
+    }
+    void *base = &arena->base[arena->first_free];
+    arena->first_free += size;
+    return base;
+}
+
+[[gnu::alloc_align(3)]]
+static INLINE void *marena_push_aligned(MArena *arena, U32 size, U32 align)
+{
+    Assert(IsPow2(align));
+
+    U32 aligned = AlignUp(arena->first_free, align);
+    if (aligned < arena->first_free) { // aligned wrapped around
+        return NULL;
+    }
+
+    if (aligned > arena->size || size > arena->size - aligned) {
+        return NULL;
+    }
+
+    void *base = &arena->base[aligned];
+    arena->first_free = aligned + size;
+
+    return base;
+}
+
+#define marena_push_type(arena, type_)\
+        marena_push_aligned((arena), sizeof(type_), _Alignof(type_))
+#define marena_push_array(arena, type_, nr_elements_)\
+        marena_push_aligned((arena), (nr_elements_) * (U32)sizeof(type_), _Alignof(type_))
+
+
+static INLINE void marena_reset(MArena *arena)
+{
+    arena->first_free = 0;
+}
+
+static INLINE void *marena_allocator_func(Allocator *allocator, AllocOperation operation , void *memory, U32 size, U32 align)
+{
+    switch (operation) {
+        case Alloc_Op_Aligned:
+            return marena_push_aligned(allocator->data, size, align);
+
+        case Alloc_Op_Free: // can't free/Free_all from  an marena
+            return NULL;
+
+        case Alloc_Op_Free_All:
+            return NULL;
+    }
+
+    Assert(false);
+}
+
+static INLINE Allocator marena_allocator(MArena *arena)
+{
+    Allocator allocator = {};
+    allocator.op_func_ptr = marena_allocator_func;
+    allocator.data = arena;
+
+    return allocator;
+}

src/platform.c

@@ -10,7 +10,7 @@
 
 U32 platform_page_size(void)
 {
-    return getpagesize();
+    return sysconf(_SC_PAGESIZE);
 }
 
 void *platform_malloc(size_t size)
@@ -23,6 +23,34 @@ void platform_free(void *mem)
     free(mem);
 }
 
+
+static void *platform_allocator_func(Allocator *allocator, AllocOperation operation , void *memory, U32 size, U32 align)
+{
+    switch (operation) {
+        case Alloc_Op_Aligned:
+            return aligned_alloc(size, align);
+
+        case Alloc_Op_Free: // can't free/Free_all from  an marena
+            free(memory);
+            return NULL;
+
+        case Alloc_Op_Free_All:
+            NotImplemented;
+            return NULL;
+    }
+
+    Assert(false);
+}
+
+Allocator platform_allocator(void)
+{
+    Allocator allocator = {};
+    allocator.op_func_ptr = platform_allocator_func;
+    allocator.data = NULL;
+
+    return allocator;
+}
+
 void *memory_allocate_and_commit(size_t size)
 {
     Assert(IsPageAligned(size));

src/platform.h

@@ -1,12 +1,16 @@
 #pragma once
 #include <stdlib.h>
+#include "base_core.h"
 
 void *platform_malloc(size_t size);
+void platform_free(void *mem);
+Allocator platform_allocator(void);
+
 U32 platform_page_size(void);
 
+// Memory functions expect mem and size to be page aligned
 void *memory_allocate_and_commit(size_t size);
 void *memory_reserve(size_t size);
 void memory_commit(void *mem, size_t size);
 void memory_decommit(void *mem, size_t size);
-
 void memory_free(void *mem, size_t size);

src/pool.c

@@ -0,0 +1,54 @@
+#include "pool.h"
+
+APool *apool_create_ex(Allocator *allocator, U32 n_elements, U32 element_size, U32 element_align)
+{
+    Assert(IsPow2(element_align));
+    U32 align = element_align;
+    if (element_align < alignof(APoolElement)) {
+        element_align = alignof(APoolElement);
+    }
+    U32 size = AlignUp(element_size, element_align);
+
+    APool *pool = allocator_push_type(allocator, APool);
+    Assert(pool != NULL);
+    pool->align = align;
+    pool->element_size = size;
+    pool->allocator = allocator;
+    pool->n_elements = n_elements;
+    pool->free_list = NULL;
+    pool->start = NULL;
+
+    if (size != APOOL_AUTOGROW) {
+        U32 total_size = n_elements * size; // Note(nos): guard against unreasonable sizes
+        U8 * start = allocator_push(allocator, total_size, align);
+        for (U32 i = 0; i < total_size; i += size) {
+            APoolElement *element = (APoolElement *)&start[i];
+            element->next = pool->free_list;
+            pool->free_list = element;
+        }
+        pool->start = start;
+    }
+
+    return pool;
+}
+
+void *apool_alloc(APool *pool)
+{
+    APoolElement *element = pool->free_list;
+    if (element != NULL) {
+        pool->free_list = element->next;
+    } else if(pool->n_elements == APOOL_AUTOGROW) {
+        element = allocator_push(pool->allocator, pool->element_size, pool->align);
+    }
+
+    return element;
+}
+
+void apool_free(APool *pool, void *ptr)
+{
+    if (ptr != NULL) {
+        APoolElement *element = (APoolElement *)ptr;
+        element->next = pool->free_list;
+        pool->free_list = element;
+    }
+}

src/pool.h

@@ -0,0 +1,26 @@
+#pragma once
+#include "base_core.h"
+
+typedef union APoolElement APoolElement;
+union APoolElement {
+    APoolElement *next;       // offset from start to next free block (when not allocated)
+};
+
+typedef struct APool APool;
+struct APool {
+    APoolElement *free_list;  // free list
+    U8 *start;                // start of user buffer
+    Allocator *allocator;
+    U32 element_size;         // aligned size of each block
+    U32 n_elements;           // total number of blocks
+    U32 align;                // alignment
+};
+enum {
+    APOOL_AUTOGROW = 0
+};
+
+#define apool_create(arena, n_elements, type) \
+        apool_create_ex(arena, n_elements, sizeof(type), alignof(type));
+APool *apool_create_ex(Allocator *allocator, U32 n_elements, U32 element_size, uint32_t element_align);
+void *apool_alloc(APool *pool);
+void apool_free(APool *pool, void *element);