Formatting issue

src/arena.c

@@ -12,15 +12,15 @@ static MemoryBlock *memoryblock_allocate(U32 size, U32 commit_size, U32 page_siz
     Assert(block != NULL);
     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          = size;
     block->first_free    = MemoryBlock_Header_Size;
     block->arena_offset  = 0;
     block->prev          = NULL;
     block->committed_end = commit_size;
-
-    ASAN_POISON_MEMORY_REGION(block->base, block->size);
-    ASAN_UNPOISON_MEMORY_REGION(block, MemoryBlock_Header_Size);
     return block;
 }
 
@@ -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);
@@ -115,7 +115,7 @@ void arena_reset_to(Arena *arena, U64 total_offset)
         MemoryBlock *prev = block->prev;
 
         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 {
@@ -123,8 +123,14 @@ void arena_reset_to(Arena *arena, U64 total_offset)
             new_pos = Max(MemoryBlock_Header_Size, new_pos);
             // Disallow arbitrary pops to positions that previously were not commited.
             Assert(new_pos <= block->committed_end);
+            Assert(new_pos <= block->size);
             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;
         }
 
@@ -132,25 +138,39 @@ void arena_reset_to(Arena *arena, U64 total_offset)
     }
 }
 
-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.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_reset_to(arena, checkpoint->total_offset);
-    arena->checkpoint_level--;
+    arena->temp_level--;
 }
 
 void arena_reset(Arena *arena)
 {
     arena_reset_to(arena, 0);
 }
+

src/arena.h

@@ -4,6 +4,9 @@
 
 typedef U32 ArenaFlags;
 typedef struct ArenaOptions ArenaOptions;
+enum {
+    ArenaFlag_NoDecommit, // arena_ temp_end/reset/reset_to doesn't decommit memory
+};
 struct ArenaOptions {
     U32 size;
     U32 commit_size;
@@ -27,16 +30,16 @@ 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;
-struct ArenaCheckpoint {
+typedef struct ATemp ATemp;
+struct ATemp {
     Arena *arena;
     U64 total_offset;
 };
-#ifndef ArenaParams_Default
-#define ArenaParams_Default { .size = MB(32), .commit_size = KB(64) }
+#ifndef ArenaOptions_Default
+#define ArenaOptions_Default ((ArenaOptions){ .size = MB(32), .commit_size = KB(64) })
 #endif
 
 StaticAssert(sizeof(MemoryBlock) <= 64);
@@ -51,8 +54,10 @@ 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_temp_end(ArenaCheckpoint *checkpoint);
+void arena_trim(Arena *arena);
+
+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);
 
@@ -66,3 +71,30 @@ static INLINE U64 arena_used(const Arena *arena)
     const MemoryBlock *block = arena->current;
     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

@@ -104,12 +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
@@ -146,7 +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
  *
@@ -154,7 +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
@@ -304,6 +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

@@ -1,6 +1,8 @@
 #include "base_core.h"
 #include "arena.h"
+#include "mini_arena.h"
 #include "platform.h"
+#include "pool.h"
 #include <stdio.h>
 #include <stdlib.h>
 
@@ -67,7 +69,7 @@ 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(4)+3, 8);
     MemoryZero(ptr, MB(2));
 
@@ -76,7 +78,7 @@ 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);
 
@@ -91,12 +93,12 @@ static void arena_test_2(void)
     ((U8*)ptr)[0] = 0x73;
     ptr = arena_push(&arena, 0, KB(4));
     //((U8*)ptr)[0] = 0x73;
-    arena_reset_to(&arena, 1089);
+  //  arena_reset_to(&arena, 1089);
     arena_dump(&arena);
     arena_reset_to(&arena, 0);
-    for (U64 i = 0; i < KB(1); i++) {
-        ptr = arena_push(&arena, MB(1)  + 3, 8);
-        MemoryZero(ptr, MB(1));
+    for (U64 i = 0; i < MB(4); i++) {
+        ptr = arena_push(&arena,  3, 1);
+        MemoryZero(ptr, 3);
     }
     arena_free(&arena);
 }
@@ -162,11 +164,265 @@ static void arena_test_4(void)
     arena_free(&arena);
 }
 
-int main(int argc, char *argv[])
+static void arena_test_allocator_interface(void)
 {
-    // arena_test_1();
-    arena_test_2();
-    // arena_test_3();
-    arena_test_4();
+    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

@@ -1,96 +1,121 @@
 #pragma once
 #include "base_core.h"
 
-typedef struct MiniArena MiniArena;
-struct MiniArena {
-    U8 *start;  // start of user buffer
-    U8 *curr;   // next alloc point
-    U8 *end;    // one past end of user buffer
-    int checkpoint_level;  // level of miniarenatmp_begin stacks
+// 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 MiniArenaCheckpoint MiniArenaCheckpoint;
-struct MiniArenaCheckpoint {
-    U8 *alloc_point;
-    MiniArena *arena;
+typedef struct MTemp MTemp;
+struct MTemp {
+    U32 offset;
+    MArena *arena;
 };
 
-#define LARENA_STATIC_INITIALIZER(data) LARENA_INITIALIZER((data), sizeof(data))
-#define LARENA_INITIALIZER(data, sz) {.start = (data), .curr = (data), .end = (data) + sz, .checkpoint_level = 0}
-#define LARENA_DEFINE(var_name, size_, alignment_)  \
+#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##_arena_memory;                      \
-    MiniArena var_name = LARENA_STATIC_INITIALIZER(var_name##_arena_memory.memory)
-#define LARENA_ALLOC_TYPE(allocator, type_) miniarenaalloc_aligned((allocator), sizeof(type_), _Alignof(type_))
-#define LARENA_ALLOC_ARRAY(allocator, type_, nr_elements_) miniarenaalloc_aligned((allocator), (nr_elements_) * sizeof(type_), _Alignof(type_))
-static INLINE size_t miniarena_size(const MiniArena *arena)
+        _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)
 {
-    return (size_t)(arena->end - arena->start);
+    Assert(memory != NULL);
+    arena->base       = (U8 *)memory;
+    arena->first_free = 0;
+    arena->size       = size;
 }
 
-static INLINE size_t miniarena_used(const MiniArena *arena)
+static INLINE MTemp marena_temp_begin(MArena *arena)
 {
-    return (size_t)(arena->curr - arena->start);
-}
-static INLINE size_t miniarena_available(const MiniArena *arena)
-{
-    return miniarena_size(arena) - miniarena_used(arena);
-}
-
-static INLINE void miniarena_init(MiniArena *arena, void *memory, size_t sz)
-{
-    arena->start = arena->curr = (U8 *)memory;
-    arena->end = arena->start + sz;
-}
-
-static INLINE MiniArenaCheckpoint miniarenatmp_begin(MiniArena *arena)
-{
-    MiniArenaCheckpoint checkpoint = {};
+    MTemp checkpoint = {};
 
     checkpoint.arena  = arena;
-    checkpoint.alloc_point = arena->curr;
-    arena->checkpoint_level++;
+    checkpoint.offset = arena->first_free;
+    arena->temp_level++;
 
     return checkpoint;
 }
 
-static INLINE void miniarenatmp_end(MiniArenaCheckpoint *state)
+static INLINE void marena_temp_end(MTemp *state)
 {
-    MiniArena *arena = state->arena;
-    Assert(arena->checkpoint_level > 0);
-    arena->curr = state->alloc_point;
-    arena->checkpoint_level--;
+    MArena *arena = state->arena;
+    Assert(arena->temp_level > 0);
+    arena->first_free = state->offset;
+    arena->temp_level--;
 }
-static INLINE void *miniarena_push(MiniArena *arena, size_t sz)
+
+static INLINE void *marena_push(MArena *arena, U32 size)
 {
-    if (sz > miniarena_available(arena)) {
+    if (size > arena->size - arena->first_free) {
         return NULL;
     }
-    void *start = arena->curr;
-    arena->curr += sz;
-    return start;
+    void *base = &arena->base[arena->first_free];
+    arena->first_free += size;
+    return base;
 }
 
 [[gnu::alloc_align(3)]]
-static INLINE void *miniaren_push_aligned(MiniArena *arena, size_t sz, unsigned int align)
+static INLINE void *marena_push_aligned(MArena *arena, U32 size, U32 align)
 {
     Assert(IsPow2(align));
 
-    uintptr_t curr = (uintptr_t)arena->curr;
-    uintptr_t aligned = AlignUp(curr, align);
-    U8 *start = (U8 *)aligned;
-
-    if (sz > (size_t)(arena->end - start)) {
+    U32 aligned = AlignUp(arena->first_free, align);
+    if (aligned < arena->first_free) { // aligned wrapped around
         return NULL;
     }
 
-    arena->curr = start + sz;
+    if (aligned > arena->size || size > arena->size - aligned) {
+        return NULL;
+    }
 
-    return start;
+    void *base = &arena->base[aligned];
+    arena->first_free = aligned + size;
+
+    return base;
 }
 
-static INLINE void miniarena_reset(MiniArena *arena)
+#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->curr = arena->start;
+    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

@@ -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);