.386
.model flat, stdcall

includelib msvcrt.lib
extern exit: proc
extern printf: proc

public start

.data

	column_format DB "%d ", 0
	row_format DB 0AH, 0
	message DB "Matrix: ", 0

	Matrix STRUCT
		rows DW ?			; Number of rows
		cols DW ?			; Number of columns
		data DW 100 dup(?)	; The data stored in the matrix
	Matrix ENDS

	A Matrix {03H, 03H, {01H, 02H, 03H, 04H, 05H, 06H, 07H, 08H, 09H}}
	B Matrix {03H, 03H, {01H, 02H, 03H, 04H, 05H, 06H, 07H, 08H, 09H}}
	RESULT Matrix {, , { }}

	; 3 x 3 Matrix
	;	1	2	3
	;	4	5	6
	;	7	8	9

.code

matrix_print PROC

	PUSH OFFSET message
	CALL printf
	ADD ESP, 4

	; EAX -> row count
	MOV EAX, -1
	MOV EDX, 0

	; ESI is pointing to the data stored in the matrix
	MOV ESI, [ESP + 4]

	rows_loop:
		; We increment the row count, reset the column count and then we check to see if we are out of bounds
		INC EAX
		; EBX -> column count
		MOV EBX, -1
		MOV CX, WORD PTR[ESI]
		CMP CX, AX
		JE finish

		; These registers are saved on the stack
		; because the printf function modifies them
		PUSH EAX
		PUSH ECX
		PUSH EDX

		PUSH OFFSET row_format
		CALL printf
		ADD ESP, 4

		POP EDX
		POP ECX
		POP EAX

		cols_loop:
			; We increment the column count and then we check to see if we are out of bounds
			; If we are we go to the next row
			INC EBX
			MOV CX, WORD PTR[ESI + 2]
			CMP CX, BX
			JE rows_loop

			; EAX and EBX are saved on the stack because the current row and column are saved in them.
			; The piece of code that follows modifies these registers.

			PUSH EAX
			PUSH EBX

			; We call index converter in order to find
			; the element found at position (i, j) in the matrix
			MOV DX, WORD PTR[ESI + 2]
			PUSH EDX
			PUSH EBX
			PUSH EAX
			CALL index_converter

			; These registersr are saved on the stack
			; Because the printf function modifies them
			PUSH EAX
			PUSH ECX
			PUSH EDX

			; We write the element found at (i, j) on the screen
			MOV DX, WORD PTR[ESI + 4 + 2*EAX]
			PUSH EDX
			PUSH OFFSET column_format
			CALL printf
			ADD ESP, 8

			pop EDX
			POP ECX
			POP EAX

			; The row count and column count are restored
			POP EBX
			POP EAX

			; Go to the next element
			JMP cols_loop
	finish:

		PUSH OFFSET row_format
		CALL printf
		ADD ESP, 4

	ret 4
matrix_print ENDP

matrix_multiply PROC


matrix_multiply ENDP

index_converter PROC

	; This function maps a 2 dimensional array index into an unidimensional array index
	; using the formula: (i, j) => (i * cols + j) where cols is the number of columns of the bidimensional array
	; and i and j are the current row and column

	; The number of columns
	MOV EAX, [ESP + 12]

	; The current column
	MOV EBX, [ESP + 8]

	; The current row
	MOV ECX, [ESP + 4]

	; EAX = i * cols
	MUL CX
	; EAX = i * cols + j
	ADD EAX, EBX

	ret 12
index_converter ENDP

start:

	PUSH OFFSET A
	CALL matrix_print

	PUSH OFFSET B
	CALL matrix_print

	PUSH OFFSET RESULT
	PUSH OFFSET B
	PUSH OFFSET A
	CALL matrix_multiply

	push 0
	call exit
end start