feat(libhectic): arenas

package/c/libhectic/libhectic.c

@@ -74,3 +74,46 @@ char* log_message(LogLevel level, int line, const char *format, ...) {
 
     return timeStr;
 }
+
+// -----------
+// -- arena --
+// -----------
+
+Arena arena_init(size_t size) {
+  Arena arena;
+  arena.begin = malloc(size);
+  memset(arena.begin, 0, size);
+  arena.current = arena.begin;
+  arena.capacity = size;
+
+  return arena;
+}
+
+void *arena_alloc_or_null(Arena *arena, size_t size) {
+  if (arena->begin == 0) {
+    *arena = arena_init(ARENA_DEFAULT_SIZE);
+  }
+  size_t current = (size_t)arena->current - (size_t)arena->begin;
+  // TODO(yukkop): maybe -1
+  if (arena->capacity <= current && current < size) {
+    return NULL;
+  }
+  return arena; 
+}
+
+void arena_reset(Arena *arena) {
+  arena->current = arena->begin;
+}
+
+void arena_free(Arena *arena) {
+  free(arena->begin);
+}
+
+void *arena_alloc(Arena *arena, size_t size) {
+  void *mem = arena_alloc_or_null(arena, size);
+  if (!mem) {
+    raise_exception("Arena out of memory");
+    exit(1);
+  }
+  return mem;
+}

package/c/libhectic/libhectic.h

@@ -138,3 +138,36 @@ char* log_message(LogLevel level, int line, const char *format, ...);
     PP_CAT(raise_exception_, PP_NARG(__VA_ARGS__))(__VA_ARGS__)
 
 #endif // EPRINTF_H
+
+// -----------
+// -- arena --
+// -----------
+
+#define ARENA_DEFAULT_SIZE 1024
+
+typedef struct {
+  void *begin;
+  void *current;
+  size_t capacity; 
+} Arena;
+
+Arena arena_init(size_t size);
+
+void *arena_alloc_or_null(Arena *arena, size_t size);
+
+void arena_reset(Arena *arena);
+
+void arena_free(Arena *arena);
+
+void *arena_alloc(Arena *arena, size_t size);
+
+// TODO: mmap
+// TODO: dynamic array style
+// void *arena_realloc(Arena *arena, size_t size) {
+//   void *mem = arena_alloc_or_null(arena, size);
+//   if (!mem) {
+//     raise_exception("Arena out of memory");
+//     exit(1);
+//   }
+//   return mem;
+// }

package/c/libhectic/test/arena.c

@@ -0,0 +1,55 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include "libhectic.h"
+
+void test_arena_init() {
+  Arena arena = arena_init(128);
+  assert(arena.begin != NULL);
+  assert(arena.current == arena.begin);
+  assert(arena.capacity == 128);
+  arena_free(&arena);
+}
+
+void test_arena_alloc() {
+  Arena arena = arena_init(64);
+  void *ptr1 = arena_alloc(&arena, 16);
+  assert(ptr1 != NULL);
+  void *ptr2 = arena_alloc(&arena, 16);
+  assert(ptr2 != NULL);
+  assert((char *)ptr2 - (char *)ptr1 == 16);
+  arena_free(&arena);
+}
+
+void test_arena_alloc_or_null_out_of_memory() {
+  Arena arena = arena_init(32);
+  void *ptr = arena_alloc_or_null(&arena, 64);
+  assert(ptr == NULL);
+  arena_free(&arena);
+}
+
+void test_arena_reset() {
+  Arena arena = arena_init(64);
+  void *ptr1 = arena_alloc(&arena, 16);
+  arena_reset(&arena);
+  void *ptr2 = arena_alloc(&arena, 16);
+  assert(ptr1 == ptr2); // same address after reset
+  arena_free(&arena);
+}
+
+void test_arena_null_init() {
+  Arena arena = {0};
+  void *ptr = arena_alloc_or_null(&arena, 32);
+  assert(ptr != NULL);
+  arena_free(&arena);
+}
+
+int main() {
+  test_arena_init();
+  test_arena_alloc();
+  test_arena_alloc_or_null_out_of_memory();
+  test_arena_reset();
+  test_arena_null_init();
+  printf("All tests passed.\n");
+}

package/c/libhectic/test/test.c

@@ -27,7 +27,6 @@
 
 int main(void) {
     set_output_color_mode(COLOR_MODE_DISABLE);
-    raise_log("zalupa");
 
     TEST_RAISE_GENERIC(raise_debug, LOG_LEVEL_DEBUG, "DEBUG");
     TEST_RAISE_GENERIC(raise_log,   LOG_LEVEL_LOG,   "LOG");