Merge branch 'hexprint' into 'master'

Hexprint

It finally works!

May not be too useful, as its for real mode with bios syscalls only. I tried to preserve the si register so its more easily debugged, but haven't gotten to restoring the other general registers. We should switch to proper function calls at some point so as to not mess up state.

See merge request !4

boot.asm

@@ -14,11 +14,11 @@ st:
 	mov	cx, 0x0002	; floppy cylinder
 	call 	read_sectors_16	; read with above args
 	jnc	0x7e00		; jump to actual code
-halt:				
+halt:
 	cli			; halt if failed, loop
 	hlt
 	jmp halt
-	
+
 read_sectors_16:
 	pusha
 	mov si, 0x02    ; maximum attempts - 1
@@ -34,7 +34,7 @@ read_sectors_16:
 .end:
 	popa
 	retn
-	
+
 read_fail db 'Failure to read from disk.', 13, 10, 0
 	; $ is current line, $$ is first line, db 0 is a 00000000 byte
 	; So, pad the code with 0s until you reach 510 bytes
@@ -44,8 +44,9 @@ times 510 - ($ - $$) db 0
 ;---------------- BOOTLOADER CODE ----------------;
 ls:	mov si, str1	; pointer to string in si
 	call PrintStr	; print string
-	jmp Main			; 
+	jmp Main			;
 	hlt
+
 ;---------------- SCREEN FUNCTIONS ---------------;
 PrintStr:	; print string at SI
 nextChar:
@@ -64,13 +65,47 @@ PrintChar:	; print char at AL
 	mov bl, 0x07	; light gray
 	int 0x10	; print character
 	ret
-;------------------ DATA BLOCK ------------------;
 
-str1 db 'Hello World', 0		;stuff
+PrintHexStr: 			; print <ax> bytes starting at [si]
+	mov di, si		; initilize the loop registers
+	mov dx, si
+	add dx, ax
+nexthchar:
+	cmp di, dx
+	jge exith 		; NO IDEA HOW THIS WORKS
+	mov al, BYTE [di]	; grab next char
+	call PrintHexChar	; else print char
+	inc di
+	jmp nexthchar	; loop
+	exith:
+	ret
+
+PrintHexChar:
+	;; call PrintChar
+	xor ebx, ebx
+	mov cl, al
+	mov bl, al
+	and bl, 0xf0
+	shr bl, 4
+	mov al, BYTE  [hexChars + ebx]
+	call PrintChar
+	mov bl, cl
+	and bl, 0x0f
+	mov al, BYTE  [hexChars + ebx]
+	call PrintChar
+	ret
+
+;------------------ DATA BLOCK ------------------;
+str1 db 'Hello World', 0	; Hello World
 str2 db 'WHY IS THIS', 0
 
+hexChars db '0123456789abcdef'		; Used for hex formatting
+
 Main:	;main section
 	nop
 	nop
 	mov si, str2
 	call PrintStr
+	mov si, str1
+	mov ax, 10
+	call PrintHexStr	; print string