From: John Tsiombikas <nuclear@member.fsf.org>
Date: Mon, 14 Dec 2020 08:03:07 +0000 (+0200)
Subject: initial commit
X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?p=bootsplash;a=commitdiff_plain;h=8a2e90cd377e7177f32ffc3ffc30a508e3f5f474

initial commit
---

8a2e90cd377e7177f32ffc3ffc30a508e3f5f474
diff --git a/.gdbinit b/.gdbinit
new file mode 100644
index 0000000..f0a6182
--- /dev/null
+++ b/.gdbinit
@@ -0,0 +1,4 @@
+target remote localhost:1234
+disp/i $pc
+set disassembly-flavor intel
+set architecture i8086
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..d9e3493
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+*.swp
+*.bin
+*.img
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..a9d1f17
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,17 @@
+bin = bootsplash.bin
+img = bootsplash.img
+
+$(img): $(bin)
+	dd if=/dev/zero of=$@ bs=512 count=2880
+	dd if=$< of=$@ bs=512 conv=notrunc
+
+$(bin): bootsplash.asm
+	nasm -f bin -o $@ $<
+
+.PHONY: run
+run: $(img)
+	qemu-system-i386 -fda $<
+
+.PHONY: debug
+debug: $(img)
+	qemu-system-i386 -S -s -fda $<
diff --git a/bootsplash.asm b/bootsplash.asm
new file mode 100644
index 0000000..26f557a
--- /dev/null
+++ b/bootsplash.asm
@@ -0,0 +1,94 @@
+	org 7c00h
+	bits 16
+
+stacktop equ 7b00h
+boot_driveno equ 7b00h	; 1 byte
+stage2_size equ stage2_end - stage2_start
+
+start:
+	xor ax, ax
+	mov ds, ax
+	mov es, ax
+	mov ss, ax
+	mov gs, ax
+	mov fs, ax
+
+	mov sp, stacktop
+	mov [boot_driveno], dl
+
+	; load the rest of the code at 7e00
+	xor ax, ax
+	mov es, ax
+	mov bx, stage2_start
+	mov ah, 2		; read sectors LBA call
+	mov al, (stage2_size + 511) / 512  ; num sectors
+	mov cx, 2		; ch: cylinder, cl: sector
+	xor dx, dx		; dh: head
+	mov dl, [boot_driveno]
+	int 13h
+	jnc stage2_start	; loaded successfully, jump to it
+
+	; failed to load second sector
+	mov ax, str_load_fail
+	call printstr
+.hang:	cli
+	hlt
+	jmp .hang
+
+	; expects string ptr in ax
+printstr:
+	mov bx, ax
+.loop:	mov al, [bx]
+	inc bx
+	test al, al
+	jz .done
+	mov ah, 0eh
+	mov bx, 7
+	int 10h
+	jmp .loop
+.done:	ret
+
+str_load_fail db "Failed to load second stage!",0
+str_foo db "Loaded 2nd stage boot loader",0
+
+
+	times 510-($-$$) db 0
+	dw 0xaa55
+
+	; start of the second stage
+stage2_start:
+	mov ax, 13h
+	int 10h
+
+	mov ax, 0a000h
+	mov es, ax
+	xor di, di
+	mov cx, 32000
+	mov ax, 0505h
+	rep stosw
+
+	call waitkey
+
+	mov ax, 3
+	int 10h
+
+	xor ax, ax
+	mov es, ax
+
+	mov ax, str_foo
+	call printstr
+
+.hang:	cli
+	hlt
+	jmp .hang
+
+waitkey:
+	in al, 64h
+	test al, 1
+	jz waitkey
+	in al, 60h
+	ret
+
+stage2_end:
+
+; vi:set ft=nasm: