From 4502339527c6cc49c61035782a5560ce120d6794 Mon Sep 17 00:00:00 2001
From: Jason Hilder <jhilder95@gmail.com>
Date: Sat, 8 Feb 2025 08:03:27 +0200
Subject: [PATCH] Getting allocators and types under control.

---
 jh.h     |  8 +++----
 jh_mem.h | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 74 insertions(+), 4 deletions(-)

diff --git a/jh.h b/jh.h
index c22c3a3..b9afaa2 100644
--- a/jh.h
+++ b/jh.h
@@ -19,21 +19,21 @@ To use this library, do this in *one* C:
 #ifndef JH_INCLUDED
 #define JH_INCLUDED
 
+#include <stdio.h>
+
+typedef uint8_t   byte;
 typedef uint8_t   u8;
 typedef uint16_t  u16;
 typedef uint32_t  u32;
 typedef uint64_t  u64;
 
 typedef char      i8;
-typedef int16_t   i32;
+typedef int16_t   i16;
 typedef int32_t   i32;
 typedef float     f32;
 typedef double    f64;
-typedef char      byte;
-typedef char16_t  c16;
 
 typedef uintptr_t uptr;
-typedef ptrdiff_t size;
 typedef size_t    usize;
 
 void jh_sort_int_array(int* array, size_t arrlen, const char* order);
diff --git a/jh_mem.h b/jh_mem.h
index a5347b5..726eddd 100644
--- a/jh_mem.h
+++ b/jh_mem.h
@@ -15,9 +15,79 @@ A implementation of the above with changes were I felt I needed them.
 To use this library, do this in *one* C:
 	#define JH_MEM_IMPLEMENTATION
 	#include "jh_io.h"
+
+NOTE:
+This is intended to be used with the jh.h header.
+And will require jh.h as it uses the typedefs defined in that file. 
+
 */
 
 #ifndef JH_MEM_INCLUDED
 #define JH_MEM_INCLUDED
 
+#ifndef DEFAULT_ALIGNMENT
+#define DEFAULT_ALIGNMENT (2*sizeof(void *))
+#endif
+
+typedef struct Arena Arena;
+struct Arena {
+	u8      *data;
+	usize   data_len;
+	usize   prev_offset;
+	usize   curr_offset;
+};
+
+bool is_power_of_two(uptr x);
+uptr align_forward(uptr ptr, usize align);
+void *arena_alloc_align(Arena *a, usize size, usize align);
+void *arena_alloc(Arena *a, usize size);
+
+// -------------------------------------- 
+// -------------------------------------- 
+// implementation Below
+// -------------------------------------- 
+
+
+// -------------------------------------- 
+// Arena Functions Start
+// -------------------------------------- 
+
+bool is_power_of_two(uintptr_t x) {
+	return (x & (x-1)) == 0;
+}
+
+uptr align_forward(uptr ptr, usize align) {
+	uptr p, a, modulo;
+	
+	assert(is_power_of_two(align));
+
+	p = ptr;
+	a = (uptr)align;
+	modulo = p & (a-1);
+
+	if (modulo != 0) {
+		// If 'p' address is not aligned. 
+		// push the address to the next value which is aligned
+		p += a - modulo;
+	}
+
+	return p;
+}
+
+void *arena_alloc_align(Arena *a, usize size, usize align) {
+	uptr current_ptr = (uptr)a->data + (uptr)a->curr_offset;
+	uptr offset = align_forward(current_ptr, align);
+
+	// Change to relative offset
+	offset -= (uptr)a->data;
+}
+
+void *arena_alloc(Arena *a, size_t size) {
+	return arena_alloc_align(a, size, DEFAULT_ALIGNMENT);
+}
+
+// -------------------------------------- 
+// Arena Functions END
+// -------------------------------------- 
+
 #endif