From 064fc9f2c7aa01de92cac4cf3681e634f4a42bf1 Mon Sep 17 00:00:00 2001
From: "E. Almqvist" <elalmqvist@gmail.com>
Date: Tue, 12 Jan 2021 20:28:06 +0100
Subject: [PATCH] Print sr

---
 src/bootloader.asm | 17 +++++------------
 src/elib/io.asm    | 27 ++++++++++++++++++++++++++-
 2 files changed, 31 insertions(+), 13 deletions(-)

diff --git a/src/bootloader.asm b/src/bootloader.asm
index f374456..2ee71fb 100644
--- a/src/bootloader.asm
+++ b/src/bootloader.asm
@@ -1,26 +1,19 @@
 %include "equ/BIOS.asm"
 %include "equ/ASCII.asm"
 
+; eLIB
+%include "elib/io.asm"
+
 mov ah, BIOS_MODE_TELETYPE ; enter teletype mode (BIOS)
 
 mov al, ASCII_LINEBREAK ; linebreak
 int BIOS_INT
 
-; Print "eOS"
-mov al, "e"
-int BIOS_INT 
+test db "eOS", ASCII_CARRIAGE_RETURN, ASCII_LINEBREAK 
 
-mov al, "O"
-int BIOS_INT
-
-mov al, "S"
-int BIOS_INT
 
-mov al, ASCII_CARRIAGE_RETURN
-int BIOS_INT
+; Print "eOS"
 
-mov al, ASCII_LINEBREAK ; linebreak
-int BIOS_INT
 
 ; ALPHABET PRINT TEST
 mov al, 64 ; one less than A since we are printing in a loop and it increments before sys interupt
diff --git a/src/elib/io.asm b/src/elib/io.asm
index 49b94f2..5607c03 100644
--- a/src/elib/io.asm
+++ b/src/elib/io.asm
@@ -1,2 +1,27 @@
 ; eLibrary
-; Input/Output sr
+; Input/Output subroutines
+
+; String structure
+; ASCII Offset = 8 bits
+; Array of the char  bytes, ending with 0 (ASCII_END)
+
+eLIB_STR_OFFSET equ 8 ; 8 bits
+
+print:	; Subroutine to print strings (from stack)
+	; Input: RCX, takes pointer to string from stack
+	pop rcx
+
+	; rcx now holds the starting point (address)
+
+	printLoop:
+		; Print the char
+		mov al, [rcx] ; dereference address to get value
+		cmp al, ASCII_END ; check if ASCII end
+		je printExit ; if reached the end then return
+
+		int BIOS_INT ; system interupt (print string)
+		add rcx, eLIB_STR_OFFSET ; increase with offset
+		jmp printLoop ; loop for next char
+
+	printExit:
+		ret