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#include <sys/mman.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <assert.h>
#define OK 0
#define ERR_IO 1
#define ERR_PARSE 2
#define ERR_PERM 3
#define ERR_INVALID 4
enum
{
BUFFER_SIZE_SMALL = 128,
BUFFER_SIZE_DEFAULT = 256,
BUFFER_SIZE_LARGE = 512,
PATH_MAX_LEN = 4096
};
typedef uint64_t u64;
typedef uint32_t u32;
typedef uint16_t u16;
typedef uint8_t u8;
typedef int8_t i8;
typedef int16_t i16;
typedef int32_t i32;
typedef int64_t i64;
typedef i16 b16;
typedef i32 b32;
static inline u64
KiB(u64 n)
{
return n << 10;
}
static inline u64
MiB(u64 n)
{
return n << 20;
}
static inline u64
GiB(u64 n)
{
return n << 30;
}
typedef struct mem_arena mem_arena;
mem_arena *
arena_create(u64 capacity);
void
arena_destroy(mem_arena *arena);
void
arena_clear(mem_arena *arena);
/**
* Arena Helper macro's
* */
#define MIN(a, b) (((a) < (b)) ? (a) : (b))
#define MAX(a, b) (((a) > (b)) ? (a) : (b))
#define ALIGN_UP_POW2(n, p) (((u64)(n) + ((u64)(p) - 1)) & (~((u64)(p) - 1)))
/*
* Represents a disk partition with major/minor device numbers and block count.
*/
/**
* replacing malloc/free with arena allocaters
*
* */
#define ARENA_BASE_POS (sizeof(mem_arena))
// void * for the size of a pointer on the machine, 64/32bit comp
#define ARENA_ALIGN (sizeof(void *))
struct mem_arena
{
u64 capacity;
u64 pos;
};
// arena prototypes
mem_arena *
arena_create(u64 capacity);
// make it a void pointer to allow implicit conversion
void
arena_destroy(mem_arena *arena);
void *
arena_push(mem_arena *arena, u64 size, b32 non_zero);
void
arena_pop(mem_arena *arena, u64 size);
void
arena_pop_to(mem_arena *arena, u64 pos);
void
arena_clear(mem_arena *arena);
mem_arena *
arena_create(u64 capacity)
{
mem_arena *arena = mmap(0, capacity, PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_SHARED | MAP_ANONYMOUS, -1, 0);
if (arena == MAP_FAILED)
{
assert(0);
}
arena->capacity = capacity;
arena->pos = ARENA_BASE_POS;
return arena;
}
// make it a void pointer to allow implicit conversion
void
arena_destroy(mem_arena *arena)
{
munmap(arena, arena->capacity);
}
void *
arena_push(mem_arena *arena, u64 size, b32 non_zero)
{
u64 pos_aligned = ALIGN_UP_POW2(arena->pos, ARENA_ALIGN);
u64 new_pos = pos_aligned + size;
if (new_pos > arena->capacity)
{
assert(0);
return NULL;
}
arena->pos = new_pos;
// cast to u8 to be able to do pointer arithemtic
u8 *out = (u8 *)arena + pos_aligned;
if (!non_zero)
{
memset(out, 0, size);
}
return out;
}
void
arena_pop(mem_arena *arena, u64 size)
{
size = MIN(size, arena->pos - ARENA_BASE_POS);
arena->pos -= size;
}
void
arena_pop_to(mem_arena *arena, u64 pos)
{
u64 size = pos < arena->pos ? arena->pos - pos : 0;
arena_pop(arena, size);
}
void
arena_clear(mem_arena *arena)
{
arena_pop_to(arena, ARENA_BASE_POS);
}
#define PUSH_STRUCT(arena, T) (T *)arena_push((arena), sizeof(T), 0)
#define PUSH_STRUCT_NZ(arena, T) (T *)arena_push((arena), sizeof(T), 1)
#define PUSH_ARRAY(arena, T, n) (T *)arena_push((arena), sizeof(T) * (n), 0)
#define PUSH_ARRAY_NZ(arena, T, n) (T *)arena_push((arena), sizeof(T) * (n), 1)
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