1 files changed, 172 insertions, 0 deletions

diff --git a/base.c b/base.c
new file mode 100644
index 0000000..519e644
--- /dev/null
+++ b/base.c
@@ -0,0 +1,172 @@
+#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)