Merge pull request #10 from E-Almqvist/dev

Dev

src/bootloader.asm

@@ -1,19 +1,21 @@
 [org 0x7c00] ; bootsector
 
-	mov bx, welcomeString		; Print the welcome string
+	mov bx, welcome_string		; Print the welcome string
 	call println
 
-	mov bx, infoString		; Print version info
+	mov bx, info_string		; Print version info
 	call println
 
-	mov bx, hexTestPrefixString	; Hex print test (not needed but fun)
-	call print
+	; Read from disk
+	mov bp, 0x8000
+	mov sp, bp ; move the stack away so that it does not get overwritten
 
-	pusha
-	mov dx, 0x002e ; test the conversion
-	call hexToASCII
-	call println
-	popa
+	mov bx, 0x9000
+	mov dh, 2 ; read 2 sectors
+	call disk_read ; read
+
+	mov dx, [0x9000]
+	call print_hex
 
 	jmp $  ; inf loop
 
@@ -22,12 +24,14 @@
 %include "equ/ASCII.asm"
 
 ; SRs
-%include "elib/io.asm"
 %include "elib/convert.asm"
+%include "elib/io.asm"
+
+%include "elib/bios_disk.asm"
 
-welcomeString:		db "Welcome to: e Operating-System (eOS)", ASCII_END
-infoString: 		db "Version 2021 0.0", ASCII_END
-hexTestPrefixString:	db "Hex printing test: ", ASCII_END
+welcome_string:		db "e Operating-System (eOS)", ASCII_END
+info_string: 		db "Version 2021 0.0", ASCII_END
+read_test_string:	db "Disk read: ", ASCII_END
 
 times 510-($-$$) db 0
 db 0x55, 0xaa ; magic BIOS numbers

src/bootloader_bios_disk.asm

@@ -1,5 +0,0 @@
-disk_read:
-	pusha
-
-	mov ah, BIOS_DISK_READ 
-	mov al, dh ; number of sectors to read

src/elib/bios_disk.asm

@@ -0,0 +1,38 @@
+disk_read:
+	pusha
+
+	push dx
+	mov ah, BIOS_DISK_READ 
+	mov al, dh ; sector count 
+	mov cl, 0x02
+
+	mov ch, 0x00 ; read from first cylinder
+	mov dh, 0x00 ; head
+
+	; data pointer: es:bx (standard)
+	int BIOS_DISK_INT ; do the interrupt
+	jc read_error ; if flag is set then jump to error
+
+	pop dx
+	cmp al, dh
+	jne sector_error
+	
+	popa
+	ret 
+
+sector_error:
+	mov bx, sector_error_string
+	call println
+
+read_error:
+	mov bx, read_error_string
+	call println
+
+	mov dh, ah
+	call print_hex 
+
+disk_loop:
+	jmp $
+
+read_error_string: 	db "Disk read error", ASCII_END
+sector_error_string:	db "Invalid number of sectors read", ASCII_END

src/elib/convert.asm

@@ -5,7 +5,7 @@ HEX_OUT: db "0x0000", ASCII_END
 ; since it fills the register with the desired 
 ; pointer toward the string.
 
-hexToASCII:
+hex_to_ascii:
 	mov cx, 0 ; incrementor
 
 	hexloop:

src/elib/io.asm

@@ -40,3 +40,13 @@ println:
 
 	popa
 	ret 
+
+
+; Subroutine to print a hex value
+print_hex:
+	pusha
+	call hex_to_ascii
+	call print
+	popa
+
+	ret