+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+@ Name:
+@ seed_rng
+@ Description:
+@ Generate seed from keyboard input.
+@ Call Stack:
+@ <empty>
+@ Return Stack:
+@ <empty>
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+#include <logic.pvvs>
+NSSVTSSSSSTTN | MARK: 10000011 (seed_rng)
+
+SSSTSSSSN | PUSH 16 (loop counter)
+SSSSN | PUSH 0 (rng seed)
+
+NSSVTSSSSSTTSSSSSSSSN | MARK: 10000011 00000000 (seed_rng:main loop)
+@ Get character from user and print ASCII '.' as feedback.
+SSSTTSSSSSSSSSSSSN | PUSH 0x3000 (USER_INPUT_BUFFER address)
+TNTS | GETCHAR
+SSSTSTTTSN | PUSH ASCII '.'
+TNSS | PUTCHAR
+@ Left shift the seed by 4 bits.
+SSSTSSN | PUSH 4 (shift count)
+NSTTSTTSTN | JSR > 101101 (lshift)
+@ XOR seed with character from user.
+SSSTTSSSSSSSSSSSSN | PUSH 0x3000 (USER_INPUT_BUFFER address)
+TTT | LOAD
+NSTTSTSTTN | JSR > 101011 (xor)
+@ Decrement counter
+SNT | SWAP
+SSSTN | PUSH +1
+TSST | SUBTRACT
+@ Test for loop completion
+SNS | DUP
+NTSTSSSSSTTSSSSSSSTN | BRZ > 10000011 00000001 (seed_rng:cleanup and return)
+SNT | SWAP
+NSNTSSSSSTTSSSSSSSSN | JMP > 10000011 00000000 (seed_rng:main loop)
+
+@ Store seed, clean up and return.
+NSSVTSSSSSTTSSSSSSSTN | MARK: 10000011 00000001 (seed_rng:cleanup and return)
+SNN | DROP
+SSSSN | PUSH 0 (seed address)
+SNT | SWAP
+TTS | STORE
+SSSTSTSN | PUSH ASCII '\n'
+SSSTSTSN | PUSH ASCII '\n'
+TNSS | PUTCHAR
+TNSS | PUTCHAR
+NTN | RTS
+
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+@ Name:
+@ is_room_adjacent
+@ Description:
+@ Checks if 'room_number' is adjacent to the current player room.
+@ Call Stack:
+@ room_number <-- TOS
+@ Return Stack:
+@ (1 or 0) for true/false <-- TOS
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+#include <stack.pvvs>
+NSSVTSTSSTSSN | MARK: 10100100 (is_room_adjacent)
+
+SSSTSSSSSSSSSSTTN | PUSH 0x1003 (ptr to number_of_tunnels_per_room)
+TTT | LOAD
+SSSTN | PUSH +1
+TSST | SUBTRACT
+
+@ TOS> tunnel_index, destination_room_num
+NSSVTSTSSTSSSSSSSSSSN | MARK: 10100100 00000000 (is_room_adjacent:main_loop)
+SSSTSN | PUSH +2
+NSTTTSSN | JSR > 1100 (deepdup)
+SSSTSN | PUSH +2
+NSTTTSSN | JSR > 1100 (deepdup)
+SSSTSSSSSSSSSTTSN | PUSH 0x1006 (ptr to player_location)
+TTT | LOAD
+NSTTSSSTSSSN | JSR > 10001000 (get_tunnel_destination)
+TSST | SUBTRACT
+NTSTSTSSTSSSSSSSSSTN | BRZ > 10100100 00000001 (is_room_adjacent:found_tunnel)
+SSSTN | PUSH +1
+TSST | SUBTRACT
+SNS | DUP
+NTTTSTSSTSSSSSSSSTSN | BMI > 10100100 00000010 (is_room_adjacent:no_match)
+NSNTSTSSTSSSSSSSSSSN | JMP > 10100100 00000000 (is_room_adjacent:main_loop)
+
+NSSVTSTSSTSSSSSSSSSTN | MARK: 10100100 00000001 (is_room_adjacent:found_tunnel)
+SNN | DROP
+SNN | DROP
+SSSTN | PUSH +1
+NTN | RTS
+
+NSSVTSTSSTSSSSSSSSTSN | MARK: 10100100 00000010 (is_room_adjacent:no_match)
+SNN | DROP
+SNN | DROP
+SSSSN | PUSH 0
+NTN | RTS
+
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+@ Name:
+@ move_player
+@ Description:
+@ Prompts the player for a room number. Moves to that room, checking the new
+@ environment and executing consequences (fell in a pit, etc) as appropriate.
+@ Call Stack:
+@ <empty>
+@ Return Stack:
+@ <empty>
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+#include <stdio.pvvs>
+#include <convert.pvvs>
+#include <math.pvvs>
+#include <string.pvvs>
+NSSVTSTSSSTTN | MARK: 10100011 (move_player)
+
+A"To which room do you wish to move?\n"
+SSSSN | PUSH 0 (number of string substitutions)
+NSTTSSSN | JSR > 1000 (printf)
+SSSTTSSSSSSSSSSSSN | PUSH 0x3000 (buffer address)
+SSSTTSSSSSSSSSSSSN | PUSH 0x3000 (buffer size)
+NSTTSSSTSN | JSR > 100010 (get_user_string)
+SSSTTSSSSSSSSSSSSN | PUSH 0x3000 (USER_INPUT_BUFFER address)
+NSTTTSSSSN | JSR > 110000 (atoi)
+SNN | DROP
+
+@ The desired room number is now on the TOS. Verify that it is valid.
+SNS | DUP
+NSTTSTSSTSSN | JSR > 10100100 (is_room_adjacent)
+NTSTSTSSSTTSSSSSSSTN | BRZ > 10100011 00000001 (invalid room number)
+NSNTSTSSSTTSSSSSSSSN | JMP > 10100011 00000000 (valid room number)
+
+NSSVTSTSSSTTSSSSSSSTN | MARK: 10100011 00000001 (invalid room number)
+@ TOS> room_number
+SNN | DROP
+A"*Oof!* (you hit the wall)\n"
+SSSSN | PUSH 0 (number of string substitutions)
+NSTTSSSN | JSR > 1000 (printf)
+NSTTSSTTN | JSR > 10011 (fastrand)
+SSSTTSN | PUSH 6 (chance)
+TSTT | MODULO
+NTSTSTSSSTTSSSSSSTSN | BRZ > 10100011 00000010 (woke the wumpus)
+NTN | RTS
+NSSVTSTSSSTTSSSSSSTSN | MARK: 10100011 00000010 (woke the wumpus)
+A"Your colorful comments awaken the wumpus!\n"
+SSSSN | PUSH 0 (number of string substitutions)
+NSTTSSSN | JSR > 1000 (printf)
+NSTTSSTTN | JSR > 10011 (fastrand)
+SSSTSSSSSSSSSSTTN | PUSH 0x1003 (ptr to number of tunnels per room)
+TSTT | MODULO
+SSSTSSSSSSSSSTTTN | PUSH 0x1007 (ptr to wumpus location)
+TTT | LOAD
+NSTTSSSTSSSN | JSR > 10001000 (get_tunnel_destination)
+SSSTSSSSSSSSSTTTN | PUSH 0x1007 (ptr to wumpus location)
+SNT | SWAP
+TTS | STORE
+SSSTSSSSSSSSSTTSN | PUSH 0x1006 (ptr to player location)
+TTT | LOAD
+NSTTSTSSSSSN | JSR > 10100000 (room_has_wumpus)
+NTSTSTSSSTTSSSSSSTTN | BRZ > 10100011 00000011 (wumpus did not move to player)
+NSTTTTTTTTTSSSSSSSSN | JSR > 11111111 00000000 (wump_kill)
+SSSSN | PUSH 0 (number of string substitutions)
+NSTTSSSN | JSR > 1000 (printf)
+NNN | DIE
+NSSVTSTSSSTTSSSSSSTTN | MARK: 10100011 00000011 (wumpus did not move to player)
+NTN | RTS
+
+NSSVTSTSSSTTSSSSSSSSN | MARK: 10100011 00000000 (valid room number)
+@ TOS> room_number
+@ Move player to new room
+SSSTSSSSSSSSSTTSN | PUSH 0x1006 (ptr to player location)
+SNT | SWAP
+TTS | STORE
+@ Check for wumpus in new player location
+SSSTSSSSSSSSSTTSN | PUSH 0x1006 (ptr to player location)
+TTT | LOAD
+NSTTSTSSSSSN | JSR > 10100000 (room_has_wumpus)
+NTSTSTSSSTTSSSSSTSSN | BRZ > 10100011 00000100 (no wumpus in new room)
+NSTTTTTTTTTSSSSSSSSN | JSR > 11111111 00000000 (wump_kill)
+SSSSN | PUSH 0 (number of string substitutions)
+NSTTSSSN | JSR > 1000 (printf)
+NNN | DIE
+NSSVTSTSSSTTSSSSSTSSN | MARK: 10100011 00000100 (no wumpus in new room)
+@ Check for pits in new player location
+SSSTSSSSSSSSSTTSN | PUSH 0x1006 (ptr to player location)
+TTT | LOAD
+NSTTSSSTTSTN | JSR > 10001101 (room_has_pits)
+NTSTSTSSSTTSSSSSTSTN | BRZ > 10100011 00000101 (no pits in new room)
+NSTTSSTTN | JSR > 10011 (fastrand)
+SSSTTSN | PUSH 6 (chance)
+TSTT | MODULO
+NTSTSTSSSTTSSSSSTTSN | BRZ > 10100011 00000110 (survived the pits)
+NSTTTTTTTTTSSSSSTSTN | JSR > 11111111 00000101 (pit_kill)
+SSSSN | PUSH 0 (number of string substitutions)
+NSTTSSSN | JSR > 1000 (printf)
+NNN | DIE
+NSSVTSTSSSTTSSSSSTTSN | MARK: 10100011 00000110 (survived the pits)
+NSTTTTTTTTTSSSSSTTSN | JSR > 11111111 00000110 (pit_survive)
+SSSSN | PUSH 0 (number of string substitutions)
+NSTTSSSN | JSR > 1000 (printf)
+NSSVTSTSSSTTSSSSSTSTN | MARK: 10100011 00000101 (no pits in new room)
+@ Check for bats in new player location
+SSSTSSSSSSSSSTTSN | PUSH 0x1006 (ptr to player location)
+TTT | LOAD
+NSTTSSSTTSSN | JSR > 10001100 (room_has_bats)
+NTSTSTSSSTTSSSSSTTSN | BRZ > 10100011 00000110 (no bats in new room)
+A"*flap* *flap* *flap* (humongous bats pick you up and move you!)\n"
+SSSSN | PUSH 0 (number of string substitutions)
+NSTTSSSN | JSR > 1000 (printf)
+NSTTSSTTN | JSR > 10011 (fastrand)
+SSSTSSSSSSSSSSTTN | PUSH 0x1003 (ptr to number of tunnels per room)
+TSTT | MODULO
+SSSTSSSSSSSSSTTSN | PUSH 0x1006 (ptr to player location)
+TTT | LOAD
+NSTTSSSTSSSN | JSR > 10001000 (get_tunnel_destination)
+NSNTSTSSSTTSSSSSSSSN | JMP > 10100011 00000000 (valid room number)
+NSSVTSTSSSTTSSSSSTTSN | MARK: 10100011 00000110 (no bats in new room)
+NTN | RTS
+
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+@ Name:
+@ move_or_shoot
+@ Description:
+@ Parse user input, branching to the appropriate subroutine to move or shoot.
+@ This function does not perform any boundary checks/limits.
+@ Call Stack:
+@ <empty>
+@ Return Stack:
+@ <empty>
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+#include <stdio.pvvs>
+#include <string.pvvs>
+NSSVTSTSSSTSN | MARK: 10100010 (move_or_shoot)
+
+SSSTTSSSSSSSSSSSSN | PUSH 0x3000 (buffer address)
+SSSTTSSSSSSSSSSSSN | PUSH 0x3000 (buffer size)
+NSTTSSSTSN | JSR > 100010 (get_user_string)
+
+@ Examine the first character of the user input buffer for 'm' or 's'.
+@ If character is something else, prompt user to try again.
+SSSTTSSSSSSSSSSSSN | PUSH 0x3000 (USER_INPUT_BUFFER address)
+TTT | LOAD
+SSSSTTSTTSTN | PUSH 109 (ASCII 'm')
+TSST | SUBTRACT
+NTSTSTSSSTSSSSSSSSSN | BRZ > 10100010 00000000 (move)
+SSSTTSSSSSSSSSSSSN | PUSH 0x3000 (USER_INPUT_BUFFER address)
+TTT | LOAD
+SSSSTTTSSTTN | PUSH 115 (ASCII 's')
+TSST | SUBTRACT
+NTSTSTSSSTSSSSSSSSTN | BRZ > 10100010 00000001 (shoot)
+NSTTTTTTTTTSSSSTSSSN | JSR > 11111111 00001000 (problem_with_input)
+SSSSN | PUSH 0 (number of string substitutions)
+NSTTSSSN | JSR > 1000 (printf)
+NSNTSTSSSTSN | JMP > 10100010 (move_or_shoot)
+
+@ User typed 'm'
+NSSVTSTSSSTSSSSSSSSSN | MARK: 10100010 00000000 (move)
+NSTTSTSSSTTN | JSR > 10100011 (move_player)
+NTN | RTS
+
+@ User typed 's'
+NSSVTSTSSSTSSSSSSSSTN | MARK: 10100010 00000001 (shoot)
+@ TODO: JSR shoot
+NTN | RTS
+
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+@ Name:
+@ get_answer
+@ Description:
+@ Parse user input, returning 0 if user string started with 'n' or 1 if 'y'.
+@ This function does not perform any boundary checks/limits.
+@ Call Stack:
+@ <empty>
+@ Return Stack:
+@ (1 or 0 for True/False) <--- TOS
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+#include <stdio.pvvs>
+#include <string.pvvs>
+NSSVTSSTTSSSN | MARK: 10011000 (get_answer)
+
+@ TODO: Consider extending the GETCHAR instruction in VVS to indicate an empty
+@ buffer instead of blocking. This would allow a character by character
+@ check without printing a slew of retry messages if the buffer is
+@ non-empty.
+SSSTTSSSSSSSSSSSSN | PUSH 0x3000 (buffer address)
+SSSTTSSSSSSSSSSSSN | PUSH 0x3000 (buffer size)
+NSTTSSSTSN | JSR > 100010 (get_user_string)
+
+@ Examine the first character of the user input buffer for 'y' or 'n'.
+@ If character is something else, prompt user to try again.
+SSSTTSSSSSSSSSSSSN | PUSH 0x3000 (USER_INPUT_BUFFER address)
+TTT | LOAD
+SSSSTTTTSSTN | PUSH 121 (ASCII 'y')
+TSST | SUBTRACT
+NTSTSSTTSSSSSSSSSSSN | BRZ > 10011000 00000000 (answer: yes)
+SSSTTSSSSSSSSSSSSN | PUSH 0x3000 (USER_INPUT_BUFFER address)
+TTT | LOAD
+SSSSTTSTTTSN | PUSH 110 (ASCII 'n')
+TSST | SUBTRACT
+NTSTSSTTSSSSSSSSSSTN | BRZ > 10011000 00000001 (answer: no)
+NSTTTTTTTTTSSSSTSSSN | JSR > 11111111 00001000 (problem_with_input)
+SSSSN | PUSH 0 (number of string substitutions)
+NSTTSSSN | JSR > 1000 (printf)
+NSNTSSTTSSSN | JMP > 10011000 (get_answer)
+
+@ User typed 'y'
+NSSVTSSTTSSSSSSSSSSSN | MARK: 10011000 00000000 (answer: yes)
+SSSTN | PUSH 1
+NTN | RTS
+
+@ User typed 'n'
+NSSVTSSTTSSSSSSSSSSTN | MARK: 10011000 00000001 (answer: no)
+SSSSN | PUSH 0
+NTN | RTS
+
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+@ Name:
+@ print_cave_description
+@ Description:
+@ Prints information about the cave (number of rooms, etc).
+@ Call Stack:
+@ <empty>
+@ Return Stack:
+@ <empty>
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+#include <stdio.pvvs>
+NSSVTSSTTSTTN | MARK: 10011011 (print_cave_description)
+NSTTTTTTTTTSSSSTSTSN | JSR > 11111111 00001010 (cave_description)
+SSSTSSSSSSSSSTSTN | PUSH 0x1005 (number_of_arrows address)
+TTT | LOAD
+SSSTSSSSSSSSSSSTN | PUSH 0x1001 (number_of_pits address)
+TTT | LOAD
+SSSTSSSSSSSSSSTSN | PUSH 0x1002 (number_of_bats address)
+TTT | LOAD
+SSSTSSSSSSSSSSTTN | PUSH 0x1003 (number_of_tunnels address)
+TTT | LOAD
+SSSTSSSSSSSSSSSSN | PUSH 0x1000 (number_of_rooms address)
+TTT | LOAD
+SSSTSTN | PUSH 5 (number of substitions)
+NSTTSSSN | JSR > 1000 (printf)
+NTN | RTS
+
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+@ Name:
+@ print_room_stats
+@ Description:
+@ Prints information about current room and hints about nearby rooms.
+@ Call Stack:
+@ <empty>
+@ Return Stack:
+@ <empty>
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+#include <wump_game.pvvs>
+#include <stdio.pvvs>
+#include <stack.pvvs>
+NSSVTSTSSSSTN | MARK: 10100001 (print_room_stats)
+
+@ Print location and arrow quantity remaining.
+A"You are in room %u of the cave and have %u arrows remaining.\n"
+SSSTSSSSSSSSSTSTN | PUSH 0x1005 (number_of_arrows address)
+TTT | LOAD
+SSSTSSSSSSSSSTTSN | PUSH 0x1006 (player_location address)
+TTT | LOAD
+SSSTSN | PUSH 2 (number of substitutions)
+NSTTSSSN | JSR > 1000 (printf)
+
+@ Print if bats/pits/wumpus nearby.
+SSSTSSSSSSSSSTTSN | PUSH 0x1006 (player_location address)
+TTT | LOAD
+SNS | DUP
+NSTTSSTTTSSN | JSR > 10011100 (are_bats_near)
+NTSTSTSSSSTSSSSSSSSN | BRZ > 10100001 00000000 (no_bats)
+A"*rustle* (Bats must be nearby.)\n"
+SSSSN | PUSH 0 (number of substitutions)
+NSTTSSSN | JSR > 1000 (printf)
+NSSVTSTSSSSTSSSSSSSSN | MARK: 10100001 00000000 (no_bats)
+SNS | DUP
+NSTTSSTTTSTN | JSR > 10011101 (are_pits_near)
+NTSTSTSSSSTSSSSSSSTN | BRZ > 10100001 00000001 (no_pits)
+A"*whoosh* (You feel a draft from nearby pits.)\n"
+SSSSN | PUSH 0 (number of substitutions)
+NSTTSSSN | JSR > 1000 (printf)
+NSSVTSTSSSSTSSSSSSSTN | MARK: 10100001 00000001 (no_pits)
+NSTTSSTTTTSN | JSR > 10011110 (is_wumpus_near)
+NTSTSTSSSSTSSSSSSTSN | BRZ > 10100001 00000010 (no_wumpus)
+A"*sniff* (You smell the evil Wumpus nearby!)\n"
+SSSSN | PUSH 0 (number of substitutions)
+NSTTSSSN | JSR > 1000 (printf)
+NSSVTSTSSSSTSSSSSSTSN | MARK: 10100001 00000010 (no_wumpus)
+
+@ Print a list of nearby rooms.
+A"This room contains tunnels to the following rooms:"
+SSSSN | PUSH 0 (number of substitutions)
+NSTTSSSN | JSR > 1000 (printf)
+SSSTSSSSSSSSSTTSN | PUSH 0x1006 (player_location address)
+TTT | LOAD
+SSSTSSSSSSSSSSTTN | PUSH 0x1003 (number_of_links_per_room address)
+TTT | LOAD
+SSSTN | PUSH 1
+TSST | SUBTRACT
+@ Print one room on each pass through this loop.
+@ TOS> tunnel_index, room_number
+NSSVTSTSSSSTSSSSSSTTN | MARK: 10100001 00000011 (print_room_list_loop)
+A" %u"
+SSSTSTN | PUSH 5
+NSTTTSSN | JSR > 1100 (deepdup)
+SSSTTTN | PUSH 7
+NSTTTSSN | JSR > 1100 (deepdup)
+NSTTSSSTSSSN | JSR > 10001000 (get_tunnel_destination)
+SSSTN | PUSH 1 (number of substitutions)
+NSTTSSSN | JSR > 1000 (printf)
+@ Test for end of loop
+SNS | DUP
+NTSTSTSSSSTSSSSSTSSN | BRZ > 10100001 00000100 (print_room_list_loop_end)
+SSSTN | PUSH 1
+TSST | SUBTRACT
+NSNTSTSSSSTSSSSSSTTN | JMP > 10100001 00000011 (print_room_list_loop)
+@ Clean up and return.
+NSSVTSTSSSSTSSSSSTSSN | MARK: 10100001 00000100 (print_room_list_loop_end)
+SSSTSTSN | PUSH 10 (ASCII '\n')
+TNSS | PUTCHAR
+SNN | DROP
+SNN | DROP
+NTN | RTS
+