Read bytes from boot drive

[nameless-os.git] / print.s

diff --git a/print.s b/print.s
index ab6eef4c92c9a66441c0abd6c1999ddc61af5bd3..3a46c724efa996310ab365d46c3c6f5330e47fb2 100644 (file)
--- a/print.s
+++ b/print.s
@@ -1,12 +1,41 @@
 %define CURRENT_ADDR cs:di
 
-print_word:
+; Prints a null terminated string of your choice.
+; Arguments:
+;     CS:DI - pointer to the string you want to print
+;     BL - 0 prints newline, otherwise no
+print
+       pusha
+       mov ah, 0Eh ; teletype print
+.write2
+       mov al, [CURRENT_ADDR] ; get current char and put it in al
+       cmp al, 0 ; check if al is null (string terminator)
+       je .newline ; if it is, start a new line
+       int 10h ; otherwise write the char
+       inc di ; increment pointer to string
+       jmp .write2 ; jump back to this section
+.newline
+       cmp bl, 1
+       je .done
+       mov al, 0Dh ; carriage return
+       int 10h
+       mov al, 0Ah ; line feed
+       int 10h
+.done
+       popa
+       ret ; return
+
+; Prints a word (16-bit value) in hex format.
+; Arguments:
+;     DX - word to print
+;     BL - 0 will print a newline, 1 won't
+print_word
        pusha ; push all regs to stack
        mov di, HEX_OUT+5 ; set destination index to last char in HEX_OUT
        mov ax, dx ; copy argument to accumulator
        and al, 00001111b ; extract the low nibble of the low half of the accumulator
        call .compare ; fill in the string with correct value
-       dec di ; decrement destination index
+       dec di ; decrement string pointer
        mov ax, dx ; copy argument to accumulator
        and al, 11110000b ; extract high nibble of low half of accumulator
        shr al, 4 ; shift high nibble to low nibble
@@ -20,102 +49,88 @@ print_word:
        and al, 11110000b
        shr al, 4
        call .compare
-       jmp .write ; write string
-
-.write:
-       popa ; get back our arguments
-       mov dl, cl ; column
-       mov dh, ch ; row
-       pusha ; save registers
-       mov al, 1 ; update cursor
-       mov bh, 0 ; page number
-       mov bl, 00000111b ; colors
-       mov cx, 6 ; length of string
-       push cs ; push code segment address
-       pop es ; pop to extra segment address
-       mov bp, HEX_OUT ; offset to extra segment of string
-       mov ah, 13h ; write string
-       int 10h ; BIOS interrupt
+       mov di, HEX_OUT
+       call print ; write string
        popa
-       ret ; return
+       ret
 
-.compare:
+.compare
        cmp al, 0 ; compare al with 0
        jne .one ; if not equal, compare with 1
        mov byte [CURRENT_ADDR], '0' ; set character to ASCII 0
        ret ; return
-.one:
+.one
        cmp al, 1
        jne .two
        mov byte [CURRENT_ADDR], '1'
        ret
-.two:
+.two
        cmp al, 2
        jne .three
        mov byte [CURRENT_ADDR], '2'
        ret
-.three:
+.three
        cmp al, 3
        jne .four
        mov byte [CURRENT_ADDR], '3'
        ret
-.four:
+.four
        cmp al, 4
        jne .five
        mov byte [CURRENT_ADDR], '4'
        ret
-.five:
+.five
        cmp al, 5
        jne .six
        mov byte [CURRENT_ADDR], '5'
        ret
-.six:
+.six
        cmp al, 6
        jne .seven
        mov byte [CURRENT_ADDR], '6'
        ret
-.seven:
+.seven
        cmp al, 7
        jne .eight
        mov byte [CURRENT_ADDR], '7'
        ret
-.eight:
+.eight
        cmp al, 8
        jne .nine
        mov byte [CURRENT_ADDR], '8'
        ret
-.nine:
+.nine
        cmp al, 9
        jne .ten
        mov byte [CURRENT_ADDR], '9'
        ret
-.ten:
+.ten
        cmp al, 0Ah
        jne .eleven
        mov byte [CURRENT_ADDR], 'A'
        ret
-.eleven:
+.eleven
        cmp al, 0Bh
        jne .twelve
        mov byte [CURRENT_ADDR], 'B'
        ret
-.twelve:
+.twelve
        cmp al, 0Ch
        jne .thirteen
        mov byte [CURRENT_ADDR], 'C'
        ret
-.thirteen:
+.thirteen
        cmp al, 0Dh
        jne .fourteen
        mov byte [CURRENT_ADDR], 'D'
        ret
-.fourteen:
+.fourteen
        cmp al, 0Eh
        jne .fifteen
        mov byte [CURRENT_ADDR], 'E'
        ret
-.fifteen:
+.fifteen
        mov byte [CURRENT_ADDR], 'F'
        ret
 
-HEX_OUT: db "0x0000"
+HEX_OUT db "0x0000", 0