initial commit

diff --git a/.gdbinit b/.gdbinit
new file mode 100644 (file)
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 (file)
index 0000000..d9e3493
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+*.swp
+*.bin
+*.img

diff --git a/Makefile b/Makefile
new file mode 100644 (file)
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 (file)
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: