From 6034fe25733e8c48c8b0b03424f7d72b2a8bd75a Mon Sep 17 00:00:00 2001
From: Andrew Kesterson <andrew@aklabs.net>
Date: Fri, 23 Jan 2015 20:40:44 -0800
Subject: [PATCH] Bootloader prints a welcome string

---
 bootloader.S | 31 ++++++++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/bootloader.S b/bootloader.S
index 33672e3..9e610bf 100644
--- a/bootloader.S
+++ b/bootloader.S
@@ -1,7 +1,28 @@
-[BITS 16]	               ; 16 bit real mode code
-[ORG 0x7C00]                   ; Origin at 0x7C00 (upper end of memory)
+[bits 16]	               ; 16 bit real mode code
+[org 0x7C00]                   ; Origin at 0x7C00 (upper end of memory)
 
-JMP $                          ; hang forever
+mov si, _str_hello             ; si = source index
+call printString
+jmp $                          ; hang forever
 
-TIMES 510 - ($ - $$) db 0      ; fill up to 510 bytes with 0
-DW 0xAA55                      ; magic bootloader signature
\ No newline at end of file
+printCharacter:                ; print a single character to the display
+mov ah, 0x0e                   ; int 0x10 is the entire display control, 
+	                       ; 0x0e means teletype output
+mov bh, 0x00                   ; Print on the zero (primary) page
+mov bl, 0x07                   ; Color. 0x07 is grey on black.
+int 0x10
+ret
+
+printString:                   ; print the entire string pointed to by si
+mov al, [si]                   ; [x] == *x, dereferencing source index
+call printCharacter
+inc si
+cmp al, 0x0                    ; found the trailing NULL?
+jne printString
+ret
+
+
+_str_hello db 'Piquant v0.1 Bootloader', 0 ; String + trailing NULL
+
+times 510 - ($ - $$) db 0      ; fill up to 510 bytes with 0
+dw 0xAA55                      ; magic bootloader signature
\ No newline at end of file