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#ifndef ARENA_IMPL
#define ARENA_IMPL
#include "common.h"
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <sys/mman.h>
#include <unistd.h>
#define PAGESIZE 4096
#ifndef ARENA_MEMORY
#define ARENA_MEMORY PAGESIZE
#endif
struct Arena {
void *memory;
u64 size;
u64 pos;
} typedef Arena;
// Create an arena
Arena *ArenaAlloc(void);
// Destroy an arena
void ArenaRelease(Arena *arena);
// Push bytes on to the arena | allocating
void *ArenaPush(Arena *arena, u64 size);
void *ArenaPushZero(Arena *arena, u64 size);
#define PushArray(arena, type, count) (type *)ArenaPush((arena), sizeof(type)*(count))
#define PushArrayZero(arena, type, count) (type *)ArenaPushZero((arena), sizeof(type) * (count))
#define PushStruct(arena, type) PushArray((arena), (type), 1)
#define PushStructZero(arena, type) PushArrayZero((arena), (type), 1)
// Free some bytes by popping the stack
void ArenaPop(Arena *arena, u64 size);
// Get the number of bytes allocated
u64 ArenaGetPos(Arena *arena);
void ArenaSetPosBack(Arena *arena, u64 pos);
void ArenaClear(Arena *arena);
Arena *ArenaAlloc(void)
{
// NOTE: If the arena is created here the pointer to the memory get's overwritten with size in
// ArenaPush, so we are forced to use malloc
Arena *arena = malloc(sizeof(Arena));
arena->memory = mmap(NULL, ARENA_MEMORY, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
if (arena->memory == MAP_FAILED)
return NULL;
arena->pos = 0;
arena->size = ARENA_MEMORY;
return arena;
}
void ArenaRelease(Arena *arena)
{
munmap(arena->memory, ARENA_MEMORY);
free(arena);
}
void *ArenaPush(Arena *arena, u64 size)
{
u8 *mem;
mem = (u8 *)arena->memory + arena->pos;
arena->pos += size;
return mem;
}
void *ArenaPushZero(Arena *arena, u64 size)
{
u8 *mem;
mem = (u8 *)arena->memory + arena->pos;
bzero(mem, size);
arena->pos += size;
return mem;
}
void ArenaPop(Arena *arena, u64 size)
{
arena->pos -= size;
}
u64 ArenaGetPos(Arena *arena)
{
return arena->pos;
}
void ArenaSetPosBack(Arena *arena, u64 pos)
{
arena->pos -= pos;
}
void ArenaClear(Arena *arena)
{
bzero(arena->memory, arena->size);
arena->pos = 0;
}
#endif
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