SharedScratchCtx shared_scratch_ctx = ZI;

/* NOTE: Application will exit if arena fails to reserve or commit initial memory. */
Arena *AllocArena(u64 reserve)
{
    __prof;
    reserve += ArenaHeaderSize;

    /* Round up to nearest block size */
    u64 block_remainder = reserve % ArenaBlockSize;
    if (block_remainder > 0)
    {
        reserve += ArenaBlockSize - block_remainder;
    }

    u8 *base = ReserveMemory(reserve);
    if (!base)
    {
        /* Hard fail on memory reserve failure for now */
        /* FIXME: Enable this */
        //P_Panic(Lit("Failed to reserve memory"));
        (*(volatile int *)0) = 0;
    }
    u64 reserved = reserve;
    AddGstat(GSTAT_MEMORY_RESERVED, reserve);

    /* Commit initial block */
    base = CommitMemory(base, ArenaBlockSize);
    if (!base)
    {
        /* Hard fail on commit failure */
        /* FIXME: Enable this */
        //P_Panic(Lit("Failed to commit initial memory block: System may be out of memory"));
        (*(volatile int *)0) = 0;
    }

    Assert(((u64)base & 0xFFF) == 0);  /* Base should be 4k aligned */
    StaticAssert(ArenaHeaderSize <= ArenaBlockSize);  /* Header must fit in first block */
    StaticAssert(sizeof(Arena) <= ArenaHeaderSize);  /* Arena struct must fit in header */

    __profalloc(base, ArenaBlockSize);
    AsanPoison(base + sizeof(Arena), ArenaBlockSize - sizeof(Arena));
    AddGstat(GSTAT_MEMORY_COMMITTED, ArenaBlockSize);
    AddGstat(GSTAT_NUM_ARENAS, 1);

    /* Create & return arena header at beginning of block */
    Arena *arena = (Arena *)base;
    ZeroStruct(arena);
    arena->committed = ArenaBlockSize - ArenaHeaderSize;
    arena->reserved = reserved;
    return arena;
}

void ReleaseArena(Arena *arena)
{
    AsanUnpoison(arena, arena->committed + ArenaHeaderSize);
    __prof;
    __proffree(arena);
    AddGstat(GSTAT_MEMORY_COMMITTED, -(i64)(arena->committed - ArenaHeaderSize));
    AddGstat(GSTAT_MEMORY_RESERVED, -(i64)(arena->reserved));
    AddGstat(GSTAT_NUM_ARENAS, -1);
    ReleaseMemory(arena);
}

/* NOTE: Application will exit if arena fails to commit memory */
void *PushBytesNoZero(Arena *arena, u64 size, u64 align)
{
    Assert(align > 0);
    Assert(!arena->readonly);

    void *ptr = 0;
    u8 *base = ArenaBase(arena);

    /* Check to avoid aligning when size = 0 */
    if (size > 0)
    {
        u64 aligned_start_pos = (arena->pos + (align - 1));
        aligned_start_pos -= aligned_start_pos % align;

        u64 new_pos = aligned_start_pos + size;
        if (new_pos > arena->committed)
        {
            __profn("Arena commit");
            /* Commit new block(s) */
            u64 blocks_needed = (new_pos - arena->committed + ArenaBlockSize - 1) / ArenaBlockSize;
            u64 commit_bytes = blocks_needed * ArenaBlockSize;
            u64 new_capacity = arena->committed + commit_bytes;
            if (new_capacity > arena->reserved)
            {
                /* Hard fail if we overflow reserved memory for now */
                /* FIXME: Enable this */
                //P_Panic(Lit("Failed to commit new memory block: Overflow of reserved memory"));
                (*(volatile int *)0) = 0;
            }
            void *commit_address = base + arena->committed;
            if (!CommitMemory(commit_address, commit_bytes))
            {
                /* Hard fail on memory allocation failure for now */
                /* FIXME: Enable this */
                //P_Panic(Lit("Failed to commit new memory block: System may be out of memory"));
                (*(volatile int *)0) = 0;
            }
            arena->committed += commit_bytes;
            AddGstat(GSTAT_MEMORY_COMMITTED, commit_bytes);
            __proffree(arena);
            __profalloc(arena, arena->committed + ArenaHeaderSize);
            AsanPoison(commit_address, commit_bytes);
        }

        ptr = base + aligned_start_pos;
        AsanUnpoison(ptr, new_pos - aligned_start_pos);
        arena->pos = new_pos;
    }
    else
    {
        ptr = base + arena->pos;
    }

    return ptr;
}

/* Copies the memory from the source arena into the destination arena,
 * replacing old contents. Destination arena will be expanded if necessary. */
void CopyArena(Arena *dst, Arena *src)
{
    ResetArena(dst);
    u64 data_size = src->pos;
    u8 *data_src = ArenaBase(src);
    u8 *data_dst = PushBytesNoZero(dst, data_size, 1);
    CopyBytes(data_dst, data_src, data_size);
}

void ShrinkArena(Arena *arena)
{
    /* Not implemented */
    Assert(0);
    LAX arena;
}

void SetArenaReadonly(Arena *arena)
{
#if RtcIsEnabled
    arena->readonly = 1;
#endif
    SetMemoryReadonly(arena, arena->committed + ArenaHeaderSize);
}

void SetArenaReadWrite(Arena *arena)
{
    SetMemoryReadWrite(arena, arena->committed + ArenaHeaderSize);
#if RtcIsEnabled
    arena->readonly = 0;
#endif
}