det.asm

section	.data
	SYS_EXIT				equ	1
	SYS_WRITE			equ	4
	SYS_READ				equ	3
	KEYBOARD_SCREEN	equ	1	; the type of input/output devices (keybord, console)

	dimen				db	0
	miss				db 0
	print_invert	db	0	; for print_num procedure: if you want inverted output set it to 1
	det				dw	0
	singmap			dw 0	; singmap for the matrix; Note: with dw matrix cant store more than 16 values
	negnum			db 0

; Messages
	msg_intro db 'The program for calculating the determinant of the matrix', 0xa, 0xa
	msg_intro_len	equ	$ - msg_intro

	msg_dimen db 'Dimension of the matrix = '
	msg_dimen_len	equ	$ - msg_dimen

	msg_GenInvit db 0xa, 'Input values for elements of the matrix:', 0xa
	msg_GenInvit_len	equ	$ - msg_GenInvit

	msg_invit1 db 'matrix['
	msg_invit1_len	equ	$ - msg_invit1

	msg_invit2 db ']['
	msg_invit2_len	equ	$ - msg_invit2

	msg_invit3 db '] = '
	msg_invit3_len	equ	$ - msg_invit3

	msg_IncorInput db 'The value is not correct. Try again: '
	msg_IncorInput_len	equ	$ - msg_IncorInput

	msg_IncorDimen db 'The value of dimension is not correct. It can not be more than 4. Try again: ', 0xa
	msg_IncorDimen_len	equ	$ - msg_IncorDimen

	msg_space db 0x09
	msg_space_len	equ	$ - msg_space

	msg_NewLine db 0xa
	msg_NewLine_len	equ	$ - msg_NewLine

	msg_ForMatrix db 0xa, 'For the matrix:', 0xa
	msg_ForMatrix_len	equ	$ - msg_ForMatrix

	msg_DetIs db 'the determinant = '
	msg_DetIs_len	equ	$ - msg_DetIs

	msg_minus db '-'
	msg_minus_len	equ	$ - msg_minus


	matrix	times 16 dw '0'

section	.bss
	i		resb	1
	j		resb	1
	num	resw	1
	temp	resb	1
	rank	resb	1
	cur_rank	resb	1
	nod	resb	1
	tempd	resd	1
	tempw	resd	1




section	.text
    global  _start    ;must be declared for linker (ld)
	 _start:    ;tell linker entry point

	 mov	eax, SYS_WRITE
	 mov	ebx, KEYBOARD_SCREEN
	 mov	ecx, msg_intro
	 mov	edx, msg_intro_len
	 int	0x80

input_dimen:
	 mov	eax, SYS_WRITE
	 mov	ebx, KEYBOARD_SCREEN
	 mov	ecx, msg_dimen
	 mov	edx, msg_dimen_len
	 int	0x80
	 call read_num
	 mov [dimen], al
	 cmp al, 5
		JL correct_dimen

	 mov	eax, SYS_WRITE
	 mov	ebx, KEYBOARD_SCREEN
	 mov	ecx, msg_IncorDimen
	 mov	edx, msg_IncorDimen_len
	 int	0x80
	 JMP input_dimen

correct_dimen:
	 mov	eax, SYS_WRITE
	 mov	ebx, KEYBOARD_SCREEN
	 mov	ecx, msg_GenInvit
	 mov	edx, msg_GenInvit_len
	 int	0x80
	 lea esi, [matrix]	; an index of the first element of the matrix
	 mov dl, [dimen]		; a dimension of the matrix
	 call read_matrix

	 mov	eax, SYS_WRITE
	 mov	ebx, KEYBOARD_SCREEN
	 mov	ecx, msg_ForMatrix
	 mov	edx, msg_ForMatrix_len
	 int	0x80
	 lea esi, [matrix]	; an index of the first element of the matrix
	 mov dl, [dimen]		; a dimension of the matrix
	 call print_matrix

	 mov	eax, SYS_WRITE
	 mov	ebx, KEYBOARD_SCREEN
	 mov	ecx, msg_DetIs
	 mov	edx, msg_DetIs_len
	 int	0x80

	 lea esi, [matrix]	; an index of the first element of the matrix
	 mov dl, [dimen]		; a dimension of the matrix
	 cmp dl, 2
		JE det_for_2
	 cmp dl, 3
		JE det_for_3
	 cmp dl, 4
		JE det_for_4

det_for_2:
	 mov al, [esi]
	 mov dl, [esi+3]
	 imul dl
	 mov bx, ax

	 mov al, [esi+2]
	 mov dl, [esi+1]
	 imul dl

	 sub bx, ax

	 mov [det], bx

	 JMP out_of_det

det_for_3:
	 mov al, [esi]
	 mov dl, [esi+4]
	 imul dl
	 mov dl, [esi+8]
	 imul dl
	 mov [det], ax

	 mov al, [esi+6]
	 mov dl, [esi+1]
	 imul dl
	 mov dl, [esi+5]
	 imul dl
	 add [det], ax

	 mov al, [esi+3]
	 mov dl, [esi+7]
	 imul dl
	 mov dl, [esi+2]
	 imul dl
	 add [det], ax

	 mov al, [esi+6]
	 mov dl, [esi+4]
	 imul dl
	 mov dl, [esi+2]
	 imul dl
	 sub [det], ax

	 mov al, [esi]
	 mov dl, [esi+7]
	 imul dl
	 mov dl, [esi+5]
	 imul dl
	 sub [det], ax

	 mov al, [esi+3]
	 mov dl, [esi+1]
	 imul dl
	 mov dl, [esi+8]
	 imul dl
	 sub [det], ax

	 JMP out_of_det

det_for_4:
	 mov word [tempw], 0

	 mov al, [esi+5]
	 mov dl, [esi+10]
	 imul dl
	 mov dl, [esi+15]
	 imul dl
	 mov [tempw], ax

	 mov al, [esi+6]
	 mov dl, [esi+11]
	 imul dl
	 mov dl, [esi+13]
	 imul dl
	 add [tempw], ax

	 mov al, [esi+9]
	 mov dl, [esi+7]
	 imul dl
	 mov dl, [esi+14]
	 imul dl
	 add [tempw], ax

	 mov al, [esi+13]
	 mov dl, [esi+10]
	 imul dl
	 mov dl, [esi+7]
	 imul dl
	 sub [tempw], ax

	 mov al, [esi+5]
	 mov dl, [esi+11]
	 imul dl
	 mov dl, [esi+14]
	 imul dl
	 sub [tempw], ax

	 mov al, [esi+6]
	 mov dl, [esi+15]
	 imul dl
	 mov dl, [esi+9]
	 imul dl
	 sub [tempw], ax
	 mov ax, [tempw]

	 mov dl, [esi]
	 imul dl
	 mov [det], ax
	 ;

	 mov word [tempw], 0

	 mov al, [esi+4]
	 mov dl, [esi+10]
	 imul dl
	 mov dl, [esi+15]
	 imul dl
	 mov [tempw], ax

	 mov al, [esi+6]
	 mov dl, [esi+11]
	 imul dl
	 mov dl, [esi+12]
	 imul dl
	 add [tempw], ax

	 mov al, [esi+8]
	 mov dl, [esi+7]
	 imul dl
	 mov dl, [esi+14]
	 imul dl
	 add [tempw], ax

	 mov al, [esi+12]
	 mov dl, [esi+10]
	 imul dl
	 mov dl, [esi+7]
	 imul dl
	 sub [tempw], ax

	 mov al, [esi+4]
	 mov dl, [esi+11]
	 imul dl
	 mov dl, [esi+14]
	 imul dl
	 sub [tempw], ax

	 mov al, [esi+6]
	 mov dl, [esi+15]
	 imul dl
	 mov dl, [esi+8]
	 imul dl
	 sub [tempw], ax
	 mov ax, [tempw]

	 mov dl, [esi+1]
	 imul dl
	 sub [det], ax
	 ;

	 mov word [tempw], 0

	 mov al, [esi+4]
	 mov dl, [esi+9]
	 imul dl
	 mov dl, [esi+15]
	 imul dl
	 mov [tempw], ax

	 mov al, [esi+5]
	 mov dl, [esi+11]
	 imul dl
	 mov dl, [esi+12]
	 imul dl
	 add [tempw], ax

	 mov al, [esi+8]
	 mov dl, [esi+7]
	 imul dl
	 mov dl, [esi+13]
	 imul dl
	 add [tempw], ax

	 mov al, [esi+12]
	 mov dl, [esi+9]
	 imul dl
	 mov dl, [esi+7]
	 imul dl
	 sub [tempw], ax

	 mov al, [esi+4]
	 mov dl, [esi+11]
	 imul dl
	 mov dl, [esi+13]
	 imul dl
	 sub [tempw], ax

	 mov al, [esi+5]
	 mov dl, [esi+15]
	 imul dl
	 mov dl, [esi+8]
	 imul dl
	 sub [tempw], ax
	 mov ax, [tempw]

	 mov dl, [esi+2]
	 imul dl
	 add [det], ax
	 ;

	 mov word [tempw], 0

	 mov al, [esi+4]
	 mov dl, [esi+9]
	 imul dl
	 mov dl, [esi+14]
	 imul dl
	 mov [tempw], ax

	 mov al, [esi+5]
	 mov dl, [esi+10]
	 imul dl
	 mov dl, [esi+12]
	 imul dl
	 add [tempw], ax

	 mov al, [esi+8]
	 mov dl, [esi+6]
	 imul dl
	 mov dl, [esi+13]
	 imul dl
	 add [tempw], ax

	 mov al, [esi+12]
	 mov dl, [esi+9]
	 imul dl
	 mov dl, [esi+6]
	 imul dl
	 sub [tempw], ax

	 mov al, [esi+4]
	 mov dl, [esi+10]
	 imul dl
	 mov dl, [esi+13]
	 imul dl
	 sub [tempw], ax

	 mov al, [esi+5]
	 mov dl, [esi+14]
	 imul dl
	 mov dl, [esi+8]
	 imul dl
	 sub [tempw], ax
	 mov ax, [tempw]

	 mov dl, [esi+3]
	 imul dl
	 sub [det], ax
	 ;

out_of_det:

	 mov ax, [det]
	 call print_num

		mov	eax, 1       ;system call number (sys_exit)
		mov	ebx, 0		;success exit status
		int	0x80        ;call kernel


; HowToUse (Example)
;
;	 lea esi, [matrix]	; an index of the first element of the matrix
;	 mov dl, [dimen]		; a dimension of the matrix
;	 call print_matrix
print_matrix:
	 mov byte [j], 1

	 mov al, dl
	 mul dl
	 mov cl, al

	 L3:
		 pusha
		 mov al, [esi]
		 cbw
		 call print_num

		 mov	eax, SYS_WRITE
		 mov	ebx, KEYBOARD_SCREEN
		 mov	ecx, msg_space
		 mov	edx, msg_space_len
		 int	0x80
		 popa

		inc esi

		cmp [j], dl		; where dl --dimension of matrix
			JE p_new_row

		inc byte [j]
		JMP p_the_same_row

	 p_new_row:
		mov byte [j], 1

		 pusha
		 mov	eax, SYS_WRITE
		 mov	ebx, KEYBOARD_SCREEN
		 mov	ecx, msg_NewLine
		 mov	edx, msg_NewLine_len
		 int	0x80
		 popa

	 p_the_same_row:

	 dec cl
	 JNZ L3
	 ret

; HowToUse (Example)
;
;	 lea esi, [matrix]	; an index of the first element of the matrix
;	 mov dl, [dimen]		; a dimension of the matrix
;	 call read_matrix
read_matrix:
	 mov byte [i], 1
	 mov byte [j], 1

	 mov al, dl
	 mul dl
	 mov cl, al

	 L2:
		 pusha
		 mov	eax, SYS_WRITE
		 mov	ebx, KEYBOARD_SCREEN
		 mov	ecx, msg_invit1
		 mov	edx, msg_invit1_len
		 int	0x80

		 mov al, [i]
		 cbw
		 call print_num

		 mov	eax, SYS_WRITE
		 mov	ebx, KEYBOARD_SCREEN
		 mov	ecx, msg_invit2
		 mov	edx, msg_invit2_len
		 int	0x80

		 mov al, [j]
		 cbw
		 call print_num

		 mov	eax, SYS_WRITE
		 mov	ebx, KEYBOARD_SCREEN
		 mov	ecx, msg_invit3
		 mov	edx, msg_invit3_len
		 int	0x80

		 call read_num
		 mov [esi], al
		 popa

		inc esi

		cmp [j], dl		; where dl --dimension of matrix
			JE new_row

		inc byte [j]
		JMP the_same_row

	 new_row:
		mov byte [j], 1
		inc byte [i]

	 the_same_row:

	 dec cl
	 JNZ L2
	 ret


; HowToUse (Example)
;	Example_1:
;		 mov al, [j]
;		 cbw					; extension from 8 bites to 16 bites
;		 call print_num
;
;	Example_2:
;		 mov ax, [j]
;		 call print_num
print_num:
	pusha
	cmp ax, 0
		JE print_0
		
	mov [num], ax
	shr ax, 15
	cmp ax, 0
		JE positive_num_p

	mov eax, SYS_WRITE
	mov ebx, KEYBOARD_SCREEN
	mov ecx, msg_minus
	mov edx, msg_minus_len
	int 0x80
	neg word [num]

	positive_num_p:

	mov byte [nod], 0
	mov [tempd], esp

	extract_no:
		cmp word [num], 0
			JE print_no

		inc byte [nod]
		mov dx, 0
		mov ax, word [num]
		mov bx, 10
		div bx
		push dx

		mov word [num], ax

		JMP extract_no

	print_no:
		cmp byte [nod], 0
			JE end_print

		dec byte [nod]

		cmp byte [print_invert], 1
			JE invert
		pop dx
		JMP not_invert
		invert:
			mov ebp, esp
			mov al, [nod]
			mov dx, [ebp + eax*2]
		not_invert:

		mov byte [temp], dl

		add byte [temp], '0'
		mov eax, SYS_WRITE
		mov ebx, KEYBOARD_SCREEN
		mov ecx, temp
		mov edx, 1
		int 0x80

		JMP print_no

	end_print:
	mov esp, [tempd]
	popa
	ret

	print_0:
		mov byte [temp], '0'
		mov eax, SYS_WRITE
		mov ebx, KEYBOARD_SCREEN
		mov ecx, temp
		mov edx, 1
		int 0x80
	popa
	ret



; HowToUse (Example)
;
;		 call read_num
;		 mov [num], al
read_num:
		 mov byte [num], 0
		 mov byte [miss], 0
		 mov byte [rank], 0
		 mov byte [cur_rank], 0
		 mov byte [negnum], 0
		 mov ebp, esp	;save state of stack
	read_NewChar:
		 mov	eax, SYS_READ
		 mov	ebx, KEYBOARD_SCREEN
		 mov	ecx, temp
		 mov	edx, 1
		 int	0x80

		 cmp byte [miss], '1'
			JE not_num

		 cmp byte [temp], '-'
			JNE check_num
		 cmp byte [rank], 0
			JNE set_miss
		 mov byte [negnum], 1
		 JMP read_NewChar

	check_num:
		 cmp byte [temp], '0'
			JL not_num
		 cmp byte [temp], '9'
			JG not_num

		 inc byte [rank]

		 mov al, [rank]
		 cmp al, 2
			JG not_num
		 mov al, byte [temp]

		 push ax

		 JMP read_NewChar

	not_num:
		 cmp byte [temp], 0xa
			 JE end_read

	set_miss:
		 mov byte [miss], 1

		 JMP read_NewChar

	end_read:
		 cmp byte [miss], 0
			JNE input_error

		 cmp byte [rank], 0
			JE input_error

	get_new_rank:
		 pop dx

		 sub dl, '0'	;convert from ascii to decimal

		 cmp byte [cur_rank], 0
			 JG cur_rank_more_0

		 mov bl, dl
		 mov [num], bl

		 JMP cur_rank_0


	cur_rank_more_0:
		 mov al, 1
		 mov cl, [cur_rank]
		 L1:
			 mov bl, 10
			 mul bl
		 dec cl
		 JNZ L1

		 mul dl

		 add [num], ax

	cur_rank_0:
		 inc byte [cur_rank]

		 mov al, [rank]
		 cmp byte [cur_rank], al
			JNE get_new_rank

		mov al, 1
		cmp byte [negnum], al
		 JNE positive_num

		neg byte [num]

	positive_num:

		mov al, [num]
	ret

	input_error:
			 mov	eax, SYS_WRITE
			 mov	ebx, KEYBOARD_SCREEN
			 mov	ecx, msg_IncorInput
			 mov	edx, msg_IncorInput_len
			 int	0x80

			 mov esp, ebp
			 JMP read_num