snake in masm

process	description
extend_snake	extend the head of snake
move_snake	extend the head of snake and reduce the tail
generate_food	putting a new food on the map
coordinate_plus_direction	calculating the new coordinate according to olds in ax and direction in bl
check_coordinate	checking whether the coordinate is still in map, affect cf
draw_block	drawing value in dx to the block of row bh column bl
draw_string	drawing the string which pointed by the effective address in di, to row bh, column bl, with color dh
draw_GUI	drawing the outer GUI of the game
draw_content	drawing the whole map, including the snake head, body, and food, wall
draw_score	drawing the numeric score at row bh, column bl
get_input	getting the user input from keyboard buffer and modifying direction
get_map	getting the map value of position ax, saving it to bl
set_map	setting the map value of position ax to bl
reset_screen	setting the display method to "80*25, 16 color" to reset the screen, and hiding the cursor
get_rand	getting random number not bigger than al, and saving it to ah