feat: initial commit, basic arena

niarena.h

@@ -0,0 +1,94 @@
+#pragma once
+
+#include "../ni-const/niconst.h"
+
+// If custom memory management is provided, including this
+// header can be skipped
+#ifndef NIAREA_NO_STDLIB
+#include <stdlib.h>
+#endif
+
+// The size can be defined by overriding this constant
+#ifndef NIARENA_ARENA_SIZE
+#define NIARENA_ARENA_SIZE NICONST_MIB_B(4)
+#endif
+
+// Custom memory management can be defined as well.
+// Either both or none must be defined
+#if (!defined(NIARENA_MALLOC) && defined(NIARENA_FREE)) || (defined(NIARENA_MALLOC) && !defined(NIARENA_FREE))
+#error "Either both NIARENA_MALLOC and NIARENA_FREE have to be defined or neither of them"
+#endif
+#ifndef NIARENA_MALLOC
+#define NIARENA_MALLOC(sz) malloc(sz)
+#endif
+#ifndef NIARENA_FREE
+#define NIARENA_FREE(p) free(p)
+#endif
+
+// Definitions
+typedef struct _NIArena {
+	void *buffer;
+	size_t capacity;
+	size_t offset;
+} NIArena;
+
+const char *niarena_get_error(void);
+NIArena *niarena_new(void);
+void *niarena_alloc(NIArena *arena, size_t size);
+void niarena_delete(NIArena *arena);
+
+#ifdef NIARENA_IMPLEMENTATION
+
+static const char *niarena__error_reason = "";
+
+static void
+niarena_error(const char *reason)
+{
+	niarena__error_reason = reason;
+}
+
+const char *
+niarena_get_error(void)
+{
+	return niarena__error_reason;
+}
+
+NIArena *
+niarena_new(void)
+{
+	NIArena *arena = NIARENA_MALLOC(sizeof(NIArena));
+	if(arena == NULL) {
+		niarena_error("niarena_new: out of memory allocating arena");
+		return NULL;
+	}
+	arena->buffer = NIARENA_MALLOC(NIARENA_ARENA_SIZE);
+	if(arena->buffer == NULL) {
+		NIARENA_FREE(arena);
+		niarena_error("niarena_new: out of memory allocating buffer");
+		return NULL;
+	}
+	arena->capacity = NIARENA_ARENA_SIZE;
+	return arena;
+}
+
+void *
+niarena_alloc(NIArena *arena, size_t size)
+{
+	if((arena->capacity - arena->offset) < size) {
+		// The allocation is invalid, but the contents of the arena
+		// can still be used (previous allocations).
+		niarena_error("niarena_alloc: out of memory inside of the arena");
+		return NULL;
+	}
+	arena->offset += size;
+	return (void *)((char *)arena->buffer + arena->offset);
+}
+
+void
+niarena_delete(NIArena *arena)
+{
+	NIARENA_FREE(arena->buffer);
+	NIARENA_FREE(arena);
+}
+
+#endif