Update mini arena

src/main.c

@@ -1,5 +1,6 @@
 #include "base_core.h"
 #include "arena.h"
+#include "mini_arena.h"
 #include "platform.h"
 #include <stdio.h>
 #include <stdlib.h>
@@ -91,12 +92,12 @@ 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);
 }
@@ -166,7 +167,7 @@ int main(int argc, char *argv[])
 {
     // arena_test_1();
     arena_test_2();
-    // arena_test_3();
+    arena_test_3();
     arena_test_4();
 }
 

src/mini_arena.h

@@ -1,96 +1,94 @@
 #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;   // next alloc point
+    U32 size;
+    S32 checkpoint_level;  // level of marenatmp_begin nesting
 };
 
-typedef struct MiniArenaCheckpoint MiniArenaCheckpoint;
-struct MiniArenaCheckpoint {
-    U8 *alloc_point;
-    MiniArena *arena;
+typedef struct MArenaCheckpoint MArenaCheckpoint;
+struct MArenaCheckpoint {
+    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), .base = (data), .first_free = 0, .size = (U32)sizeof(data), checkpoint_level = 0}
+#define MARENA_DEFINE(var_name, size, alignment_)  \
     struct {                                        \
-        _Alignas(alignment_) U8 memory[size_]; \
+        _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)
+    MArena var_name = MARENA_STATIC_INITIALIZER(var_name##_arena_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 MArenaCheckpoint marenatmp_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 = {};
+    MArenaCheckpoint checkpoint = {};
 
     checkpoint.arena  = arena;
-    checkpoint.alloc_point = arena->curr;
+    checkpoint.offset = arena->first_free;
     arena->checkpoint_level++;
 
     return checkpoint;
 }
 
-static INLINE void miniarenatmp_end(MiniArenaCheckpoint *state)
+static INLINE void marenatmp_end(MArenaCheckpoint *state)
 {
-    MiniArena *arena = state->arena;
+    MArena *arena = state->arena;
     Assert(arena->checkpoint_level > 0);
-    arena->curr = state->alloc_point;
+    arena->first_free = state->offset;
     arena->checkpoint_level--;
 }
-static INLINE void *miniarena_push(MiniArena *arena, size_t sz)
+
+#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)
 {
-    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 *maren_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) { // align wrapped
         return NULL;
     }
 
-    arena->curr = start + sz;
-
-    return start;
+    if (aligned > arena->size || size > arena->size - aligned) {
+        return NULL;
     }
 
-static INLINE void miniarena_reset(MiniArena *arena)
+    void *base = &arena->base[aligned];
+    arena->first_free = aligned + size;
+
+    return base;
+}
+
+static INLINE void marena_reset(MArena *arena)
 {
-    arena->curr = arena->start;
+    arena->first_free = 0;
 }