From e5890fd8f723a948fffb28cc73990c6749f36260 Mon Sep 17 00:00:00 2001
From: Elizabeth Alexander Hunt <me@liz.coffee>
Date: Wed, 7 Oct 2026 09:17:15 -0700
Subject: VBE attempt 1

---
 src/boot.asm | 25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)

(limited to 'src/boot.asm')

diff --git a/src/boot.asm b/src/boot.asm
index cbf57d6..c88f08c 100644
--- a/src/boot.asm
+++ b/src/boot.asm
@@ -1,20 +1,37 @@
 ;> The Multiboot header must be contained completely within the first 8192 bytes of the OS 
 ;> image, and must be longword (32-bit) aligned.
 MULTIBOOT_ALIGN_TO_PAGE:   equ 1 << 0
-MULTIBOOT_MEMORY_DESCRIBE: equ 1 << 2
+MULTIBOOT_MEMORY_DESCRIBE: equ 1 << 1
+MULTIBOOT_VIDEO_MODE:      equ 1 << 2
 MULTIBOOT_MAGIC:           equ 0x1BADB002
-MULTIBOOT_FLAGS:           equ (MULTIBOOT_ALIGN_TO_PAGE | MULTIBOOT_MEMORY_DESCRIBE)
+MULTIBOOT_FLAGS:           equ (MULTIBOOT_ALIGN_TO_PAGE | MULTIBOOT_MEMORY_DESCRIBE | MULTIBOOT_VIDEO_MODE)
 MULTIBOOT_CHECKSUM:        equ -(MULTIBOOT_MAGIC + MULTIBOOT_FLAGS)
-section .multiboot_header
+MULTIBOOT_VIDEO_TYPE:      equ 0
+MULTIBOOT_GODS_WIDTH:      equ 640
+MULTIBOOT_GODS_HEIGHT:     equ 480
+MULTIBOOT_VIDEO_BPP:       equ 16
+
+; We don't set flags[16] because we assemble to ELF32 so header_addr, etc is useless to us
+; (at least at the moment).
+UNUSED_BYTES_COUNT: equ 5*4
+section .multiboot_header:
+; I guess multiboot 2 requires a length field and we might migrate to that in the future.
+multiboot_header_start:
 align 4
     dd MULTIBOOT_MAGIC
     dd MULTIBOOT_FLAGS
     dd MULTIBOOT_CHECKSUM
+    times UNUSED_BYTES_COUNT db 0
+    dd MULTIBOOT_VIDEO_TYPE
+    dd MULTIBOOT_GODS_WIDTH
+    dd MULTIBOOT_GODS_HEIGHT
+    dd MULTIBOOT_VIDEO_BPP
+multiboot_header_end:
 
 STACK_SIZE: equ (1 << 14)
 section .bss
 align 16
-stack_bottom:
+stack_bottom: ; ("haha bottom" somewhere in there??)
     resb STACK_SIZE
 stack_top:
 
-- 
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