From 5ebc67833086eccb3c3b1708745c927d5bcfd811 Mon Sep 17 00:00:00 2001
From: Aiden Gall <aiden@aidengall.xyz>
Date: Wed, 15 May 2024 00:47:52 +0100
Subject: add static assertions

---
 Makefile        | 2 +-
 kernel/assert.h | 1 +
 kernel/main.c   | 3 +++
 3 files changed, 5 insertions(+), 1 deletion(-)
 create mode 100644 kernel/assert.h

diff --git a/Makefile b/Makefile
index 3039d1d..a68ae43 100644
--- a/Makefile
+++ b/Makefile
@@ -16,7 +16,7 @@ OBJ = ${CSRC:.c=.o} ${FSRC:.asm=.o}
 all: providence.img
 
 boot/boot.o: boot/bios.inc boot/page.inc boot/segdesc.inc
-kernel/main.o: kernel/util.h
+kernel/main.o: kernel/assert.h kernel/util.h
 
 providence.img: ${OBJ}
 	${CC} ${LDFLAGS} $^ ${LDLIBS} -o $@
diff --git a/kernel/assert.h b/kernel/assert.h
new file mode 100644
index 0000000..2519b7f
--- /dev/null
+++ b/kernel/assert.h
@@ -0,0 +1 @@
+#define STATIC_ASSERT(COND,MSG) typedef char static_assert_##MSG[(COND)?1:-1]
diff --git a/kernel/main.c b/kernel/main.c
index 8c120e9..0633254 100644
--- a/kernel/main.c
+++ b/kernel/main.c
@@ -1,4 +1,5 @@
 #include <stdint.h>
+#include "assert.h"
 #include "util.h"
 
 #define VGA_WIDTH 80
@@ -11,6 +12,8 @@ struct e820_entry {
 	uint32_t ext_attr;
 };
 
+STATIC_ASSERT(sizeof(struct e820_entry) == 24, e820_entry);
+
 static uint64_t *
 memsetu64(uint64_t *const dst, const uint64_t c, const uint64_t n)
 {
-- 
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