examples/hunt-the-wumpus/wump_game.pvvs

#ifndef WUMP_GAME
#define WUMP_GAME

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ (c) 2019 Aaron Taylor <ataylor at subgeniuskitty dot com>
@ See LICENSE.txt file for copyright and license details.
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@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ Name:
@   get_tunnel_destination
@ Description:
@   Returns the room number corresponding to the destination of a tunnel
@   specified by room and slot.
@ Call Stack:
@   slot
@   room_number  <-- TOS
@ Return Stack:
@   dst_room_number  <-- TOS
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
NSSVTSSSTSSSN         | MARK: 10001000 (get_tunnel_destination)
@ The pointer we seek is:
@ (room_number * room_struct_size) + 2 + slot + ROOM_DATA_BASE
@ Where the '+2' accounts for the pit and bat booleans.
NSTTSSSTSTTN          | JSR > 10001011 (get_room_struct_size)
TSSN                  | MULTIPLY
SSSTSN                | PUSH +2
TSSS                  | ADD
TSSS                  | ADD
SSSTSSSSSSSSSSSSSN    | PUSH 0x2000 (ROOM_DATA_BASE address)
TSSS                  | ADD
TTT                   | LOAD
NTN                   | RTS

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ Name:
@   get_room_struct_size
@ Description:
@   Returns the size in words of the data structure for a single room.
@   For example, with 3 links plus bat and pit booleans, the size is 5 words.
@ Call Stack:
@   <empty>
@ Return Stack:
@   size   <-- TOS
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
NSSVTSSSTSTTN         | MARK: 10001011 (get_room_struct_size)
SSSTSSSSSSSSSSTTN     | PUSH 0x1003 (GAME_DATA_BASE+3 = links_per_room address)
TTT                   | LOAD
SSSTSN                | PUSH +2
TSSS                  | ADD
NTN                   | RTS

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ Name:
@   room_has_bats
@ Description:
@   Check if room_number contains bats.
@   Returns 1 or 0 representing true or false.
@ Call Stack:
@   room_number   <-- TOS
@ Return Stack:
@   1 or 0   <-- TOS
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
NSSVTSSSTTSSN         | MARK: 10001100 (room_has_bats)
@ We seek the pointer:
@   (room_number * room_struct_size) + 1 + ROOM_DATA_BASE
@ where '+1' accounts for the offset of the bat boolean in the desired room.
NSTTSSSTSTTN          | JSR > 10001011 (get_room_struct_size)
TSSN                  | MULTIPLY
SSSTN                 | PUSH +1
TSSS                  | ADD
SSSTSSSSSSSSSSSSSN    | PUSH 0x2000 (GAME_DATA_BASE address)
TSSS                  | ADD
TTT                   | LOAD
NTN                   | RTS

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ Name:
@   room_has_pits
@ Description:
@   Check if room_number contains pits.
@   Returns 1 or 0 representing true or false.
@ Call Stack:
@   room_number   <-- TOS
@ Return Stack:
@   1 or 0   <-- TOS
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
NSSVTSSSTTSTN         | MARK: 10001101 (room_has_pits)
@ We seek the pointer:
@   (room_number * room_struct_size) + 0 + ROOM_DATA_BASE
@ where '+0' accounts for the offset of the pit boolean in the desired room.
NSTTSSSTSTTN          | JSR > 10001011 (get_room_struct_size)
TSSN                  | MULTIPLY
SSSTSSSSSSSSSSSSSN    | PUSH 0x2000 (GAME_DATA_BASE address)
TSSS                  | ADD
TTT                   | LOAD
NTN                   | RTS

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ Name:
@   room_has_wumpus
@ Description:
@   Check if room contains wumpus.
@   Returns 1 or 0 representing true or false.
@ Call Stack:
@   room_number   <-- TOS
@ Return Stack:
@   1 or 0   <-- TOS
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
NSSVTSTSSSSSN         | MARK: 10100000 (room_has_wumpus)
SSSTSSSSSSSSSTTTN     | PUSH 0x1007 (wumpus_location address)
TTT                   | LOAD
TSST                  | SUBTRACT
NTSTSTSSSSSSSSSSSSSN  | BRZ > 10100000 00000000 (room_has_wumpus:true)
SSSSN                 | PUSH 0 (false)
NTN                   | RTS
NSSVTSTSSSSSSSSSSSSSN | MARK: 10100000 00000000 (room_has_wumpus:true)
SSSTN                 | PUSH 1 (true)
NTN                   | RTS

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ Name:
@   are_bats_near
@ Description:
@   Given a room number, checks rooms within one hop for bats.
@   Returns 1 if bats are present or 0 if no bats.
@ Call Stack:
@   room_number  <-- TOS
@ Return Stack:
@   1 or 0  <-- TOS
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
#include <stack.pvvs>
NSSVTSSTTTSSN         | MARK: 10011100 (are_bats_near)

@ Prepare the stack by loading the number of links per room and decrementing.
@ We will loop until this reaches 0 or we find bats.
SSSTSSSSSSSSSSTTN     | PUSH 0x1003 (number_of_links_per_room address)
TTT                   | LOAD
SSSTN                 | PUSH 1
TSST                  | SUBTRACT

@ Check one nearby room on each pass through this loop.
@ TOS> tunnel_index, room_number
NSSVTSSTTTSSSSSSSSSSN | MARK: 10011100 00000000 (are_bats_near:loop)
SNS                   | DUP
SSSTTN                | PUSH 3
NSTTTSSN              | JSR > 1100 (deepdup)
NSTTSSSTSSSN          | JSR > 10001000 (get_tunnel_destination)
NSTTSSSTTSSN          | JSR > 10001100 (room_has_bats)
NTSTSSTTTSSSSSSSSSTN  | BRZ > 10011100 00000001 (no_bats_in_this_room)
@ Found bats. Clean up and return.
SNN                   | DROP
SNN                   | DROP
SSSTN                 | PUSH 1
NTN                   | RTS
NSSVTSSTTTSSSSSSSSSTN | MARK: 10011100 00000001 (no_bats_in_this_room)
@ Test for end of loop.
SNS                   | DUP
NTSTSSTTTSSSSSSSSTSN  | BRZ > 10011100 00000010 (are_bats_near:loop_end)
@ No bats found yet, but still need to check some rooms.
@ Decrement tunnel index and loop again.
SSSTN                 | PUSH 1
TSST                  | SUBTRACT
NSNTSSTTTSSSSSSSSSSN  | JMP > 10011100 00000000 (are_bats_near:loop)
@ No bats found in nearby rooms. Clean up and return.
NSSVTSSTTTSSSSSSSSTSN | MARK: 10011100 00000010 (are_bats_near:loop_end)
SNN                   | DROP
SNN                   | DROP
SSSSN                 | PUSH 0
NTN                   | RTS

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ Name:
@   are_pits_near
@ Description:
@   Given a room number, checks rooms within one hop for pits.
@   Returns 1 if pits are present or 0 if no pits.
@ Call Stack:
@   room_number  <-- TOS
@ Return Stack:
@   1 or 0  <-- TOS
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
#include <stack.pvvs>
NSSVTSSTTTSTN         | MARK: 10011101 (are_pits_near)

@ Prepare the stack by loading the number of links per room and decrementing.
@ We will loop until this reaches 0 or we find pits.
SSSTSSSSSSSSSSTTN     | PUSH 0x1003 (number_of_links_per_room address)
TTT                   | LOAD
SSSTN                 | PUSH 1
TSST                  | SUBTRACT

@ Check one nearby room on each pass through this loop.
@ TOS> tunnel_index, room_number
NSSVTSSTTTSTSSSSSSSSN | MARK: 10011101 00000000 (are_pits_near:loop)
SNS                   | DUP
SSSTTN                | PUSH 3
NSTTTSSN              | JSR > 1100 (deepdup)
NSTTSSSTSSSN          | JSR > 10001000 (get_tunnel_destination)
NSTTSSSTTSTN          | JSR > 10001101 (room_has_pits)
NTSTSSTTTSTSSSSSSSTN  | BRZ > 10011101 00000001 (no_pits_in_this_room)
@ Found pits. Clean up and return.
SNN                   | DROP
SNN                   | DROP
SSSTN                 | PUSH 1
NTN                   | RTS
NSSVTSSTTTSTSSSSSSSTN | MARK: 10011101 00000001 (no_pits_in_this_room)
@ Test for end of loop.
SNS                   | DUP
NTSTSSTTTSTSSSSSSTSN  | BRZ > 10011101 00000010 (are_pits_near:loop_end)
@ No pits found yet, but still need to check some rooms.
@ Decrement tunnel index and loop again.
SSSTN                 | PUSH 1
TSST                  | SUBTRACT
NSNTSSTTTSTSSSSSSSSN  | JMP > 10011101 00000000 (are_pits_near:loop)
@ No pits found in nearby rooms. Clean up and return.
NSSVTSSTTTSTSSSSSSTSN | MARK: 10011101 00000010 (are_pits_near:loop_end)
SNN                   | DROP
SNN                   | DROP
SSSSN                 | PUSH 0
NTN                   | RTS

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ Name:
@   is_wumpus_very_near
@ Description:
@   Given a room number, checks rooms within one hop for the wumpus.
@   Returns 1 if wumpus is present, otherwise 0.
@ Call Stack:
@   room_number  <-- TOS
@ Return Stack:
@   1 or 0  <-- TOS
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
#include <stack.pvvs>
NSSVTSSTTTTTN         | MARK: 10011111 (is_wumpus_very_near)

@ Prepare the stack by loading the number of links per room and decrementing.
@ We will loop until this reaches 0 or we find the wumpus.
SSSTSSSSSSSSSSTTN     | PUSH 0x1003 (number_of_links_per_room address)
TTT                   | LOAD
SSSTN                 | PUSH 1
TSST                  | SUBTRACT

@ Check one nearby room on each pass through this loop.
@ TOS> tunnel_index, room_number
NSSVTSSTTTTTSSSSSSSSN | MARK: 10011111 00000000 (is_wumpus_very_near:loop)
SNS                   | DUP
SSSTTN                | PUSH 3
NSTTTSSN              | JSR > 1100 (deepdup)
NSTTSSSTSSSN          | JSR > 10001000 (get_tunnel_destination)
NSTTSTSSSSSN          | JSR > 10100000 (room_has_wumpus)
NTSTSSTTTTTSSSSSSSTN  | BRZ > 10011111 00000001 (no_wumpus_in_this_room)
@ Found wumpus. Clean up and return.
SNN                   | DROP
SNN                   | DROP
SSSTN                 | PUSH 1
NTN                   | RTS
NSSVTSSTTTTTSSSSSSSTN | MARK: 10011111 00000001 (no_wumpus_in_this_room)
@ Test for end of loop.
SNS                   | DUP
NTSTSSTTTTTSSSSSSTSN  | BRZ > 10011111 00000010 (is_wumpus_very_near:loop_end)
@ No wumpus found yet, but still need to check some rooms.
@ Decrement tunnel index and loop again.
SSSTN                 | PUSH 1
TSST                  | SUBTRACT
NSNTSSTTTTTSSSSSSSSN  | JMP > 10011111 00000000 (is_wumpus_very_near:loop)
@ No wumpus found in nearby rooms. Clean up and return.
NSSVTSSTTTTTSSSSSSTSN | MARK: 10011111 00000010 (is_wumpus_very_near:loop_end)
SNN                   | DROP
SNN                   | DROP
SSSSN                 | PUSH 0
NTN                   | RTS

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ Name:
@   is_wumpus_near
@ Description:
@   Given a room number, checks rooms within two hops for the wumpus.
@   Returns 1 if wumpus is present, otherwise 0.
@ Call Stack:
@   room_number  <-- TOS
@ Return Stack:
@   1 or 0  <-- TOS
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
#include <stack.pvvs>
NSSVTSSTTTTSN         | MARK: 10011110 (is_wumpus_near)

@ Prepare the stack by loading the number of links per room and decrementing.
@ We will loop until this reaches 0 or we find the wumpus.
SSSTSSSSSSSSSSTTN     | PUSH 0x1003 (number_of_links_per_room address)
TTT                   | LOAD
SSSTN                 | PUSH 1
TSST                  | SUBTRACT

@ Check one nearby room and its connecting rooms on each pass through this loop.
@ TOS> tunnel_index, room_number
NSSVTSSTTTTSSSSSSSSSN | MARK: 10011110 00000000 (is_wumpus_near:loop)
SNS                   | DUP
SSSTTN                | PUSH 3
NSTTTSSN              | JSR > 1100 (deepdup)
NSTTSSSTSSSN          | JSR > 10001000 (get_tunnel_destination)
@ TOS> tunnel_endpoint, tunnel_index, room_number
SNS                   | DUP
NSTTSTSSSSSN          | JSR > 10100000 (room_has_wumpus)
SSSTN                 | PUSH 1
TSST                  | SUBTRACT
NTSTSSTTTTSSSSSSSTTN  | BRZ > 10011110 00000011 (found_wumpus_one_hop)
NSTTSSTTTTTN          | JSR > 10011111 (is_wumpus_very_near)
SSSTN                 | PUSH 1
TSST                  | SUBTRACT
NTSTSSTTTTSSSSSSTSSN  | BRZ > 10011110 00000100 (found_wumpus_two_hops)
@ Test for end of loop.
SNS                   | DUP
NTSTSSTTTTSSSSSSSTSN  | BRZ > 10011110 00000010 (is_wumpus_near:loop_end)
@ No wumpus found yet, but still need to check some rooms.
@ Decrement tunnel index and loop again.
SSSTN                 | PUSH 1
TSST                  | SUBTRACT
NSNTSSTTTTSSSSSSSSSN  | JMP > 10011110 00000000 (is_wumpus_near:loop)

@ No wumpus found in nearby rooms. Clean up and return.
NSSVTSSTTTTSSSSSSSTSN | MARK: 10011110 00000010 (is_wumpus_near:loop_end)
SNN                   | DROP
SNN                   | DROP
SSSSN                 | PUSH 0
NTN                   | RTS

@ Found wumpus. Clean up and return.
NSSVTSSTTTTSSSSSSSTTN | MARK: 10011110 00000011 (found_wumpus_one_hop)
SNN                   | DROP
NSSVTSSTTTTSSSSSSTSSN | MARK: 10011110 00000100 (found_wumpus_two_hops)
SNN                   | DROP
SNN                   | DROP
SSSTN                 | PUSH 1
NTN                   | RTS

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ 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:
@   are_rooms_adjacent
@ Description:
@   Checks if 'room_number_1' is adjacent to 'room_number_2'.
@ Call Stack:
@   room_number_2
@   room_number_1  <-- TOS
@ Return Stack:
@   (1 or 0) for true/false  <-- TOS
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
#include <stack.pvvs>
NSSVTSTSSTSSN         | MARK: 10100100 (are_rooms_adjacent)

SSSTSSSSSSSSSSTTN     | PUSH 0x1003 (ptr to number_of_tunnels_per_room)
TTT                   | LOAD
SSSTN                 | PUSH +1
TSST                  | SUBTRACT

@ TOS> tunnel_index, room_number_1, room_number_2
NSSVTSTSSTSSSSSSSSSSN | MARK: 10100100 00000000 (main_loop)
SSSTTN                | PUSH +3
NSTTTSSN              | JSR > 1100 (deepdup)
SSSTTN                | PUSH +3
NSTTTSSN              | JSR > 1100 (deepdup)
SSSTTN                | PUSH +3
NSTTTSSN              | JSR > 1100 (deepdup)
SNT                   | SWAP
NSTTSSSTSSSN          | JSR > 10001000 (get_tunnel_destination)
TSST                  | SUBTRACT
NTSTSTSSTSSSSSSSSSTN  | BRZ > 10100100 00000001 (found_tunnel)
SSSTN                 | PUSH +1
TSST                  | SUBTRACT
SNS                   | DUP
NTTTSTSSTSSSSSSSSTSN  | BMI > 10100100 00000010 (no_match)
NSNTSTSSTSSSSSSSSSSN  | JMP > 10100100 00000000 (main_loop)

NSSVTSTSSTSSSSSSSSSTN | MARK: 10100100 00000001 (found_tunnel)
SNN                   | DROP
SNN                   | DROP
SNN                   | DROP
SSSTN                 | PUSH +1
NTN                   | RTS

NSSVTSTSSTSSSSSSSSTSN | MARK: 10100100 00000010 (no_match)
SNN                   | DROP
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
SSSTSSSSSSSSSTTSN     | PUSH 0x1006 (ptr to player_location)
TTT                   | LOAD
NSTTSTSSTSSN          | JSR > 10100100 (are_rooms_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:
@   shoot_arrow
@ Description:
@   Prompt user for list of rooms. Shoots an arrow through each room, checking
@     the new environment and executing consequences (fell in a pit, etc) as
@     appropriate.
@ Call Stack:
@   <empty>
@ Return Stack:
@   <empty>
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
#include <string.pvvs>
#include <stack.pvvs>
#include <stdio.pvvs>
#include <math.pvvs>
#include <wump_strings.pvvs>
NSSVTSSTTSSTN         | MARK: 10011001 (shoot_arrow)

A"Through which rooms do you wish to shoot your arrow?\n(type %u room numbers separated by spaces)\n"
SSSTSSSSSSSSSTSSN     | PUSH 0x1004 (ptr to max_arrow_flight_distance)
TTT                   | LOAD
SSSTN                 | PUSH 1 (number of string substitutions)
NSTTSSSN              | JSR > 1000 (printf)
SSSTTSSSSSSSSSSSSN    | PUSH 0x3000 (buffer address)
SSSTTSSSSSSSSSSSSN    | PUSH 0x3000 (buffer size)
NSTTSSSTSN            | JSR > 100010 (get_user_string)

@ Loop, converting one room number from the user string per pass.
@ But first, prepare the stack for the loop.
SSSTTSSSSSSSSSSSSN    | PUSH 0x3000 (USER_INPUT_BUFFER address)
SSSTSSSSSSSSSTSSN     | PUSH 0x1004 (ptr to max_arrow_flight_distance)
TTT                   | LOAD
@ TOS> loop_counter, ptr_to_user_string
NSSVTSSTTSSTSSSSSSSSN | MARK: 10011001 00000000 (process_room_loop)
@ Test for end of loop (counter == 0)
SNS                   | DUP
NTSTSSTTSSTSSSSSSSTN  | BRZ > 10011001 00000001 (end of process_room_loop)
@ Now jump forward in the user string to the next ASCII digit (or null term).
SNT                   | SWAP
NSSVTSSTTSSTSSSSSSTSN | MARK: 10011001 00000010 (next_ascii_digit_loop)
SNS                   | DUP
TTT                   | LOAD
SNS                   | DUP
NSTTSSSSTN            | JSR > 100001 (isdigit)
NTSTSSTTSSTSSSSSSTTN  | BRZ > 10011001 00000011 (ascii_term_test)
SNN                   | DROP
NSNTSSTTSSTSSSSSTSSN  | JMP > 10011001 00000100 (next_ascii_digit_loop_end)
NSSVTSSTTSSTSSSSSSTTN | MARK: 10011001 00000011 (ascii_term_test)
NTSTSSTTSSTSSSSSTSSN  | BRZ > 10011001 00000100 (next_ascii_digit_loop_end)
SSSTN                 | PUSH 1
TSSS                  | ADD
NSNTSSTTSSTSSSSSSTSN  | JMP > 10011001 00000010 (next_ascii_digit_loop)
NSSVTSSTTSSTSSSSSTSSN | MARK: 10011001 00000100 (next_ascii_digit_loop_end)
@ Call atoi with the newly updated pointer to process another room number.
NSTTTSSSSN            | JSR > 110000 (atoi)
SNT                   | SWAP
SSSTTN                | PUSH 3 (rotation_depth)
NSTTSTSN              | JSR > 1010 (stackrotate)
@ Decrement the loop counter and loop again.
SNT                   | SWAP
SSSTN                 | PUSH 1
TSST                  | SUBTRACT
NSNTSSTTSSTSSSSSSSSN  | JMP > 10011001 00000000 (process_room_loop)
@ Loop is complete. Moving on.
NSSVTSSTTSSTSSSSSSSTN | MARK: 10011001 00000001 (end of process_room_loop)
SNN                   | DROP
SNN                   | DROP

@ Stack now contains only integers for room numbers (zero padded to full count).
@ They are in reverse order, so reverse again.
@ Temporarily use the USER_INPUT_BUFFER as a loop counter.
SSSTTSSSSSSSSSSSSN    | PUSH 0x3000
SSSTSSSSSSSSSTSSN     | PUSH 0x1004 (ptr to max_arrow_flight_distance)
TTT                   | LOAD
TTS                   | STORE
@ Now perform the reversal.
NSSVTSSTTSSTSSSSSTSTN | MARK: 10011001 00000101 (reverse_loop)
@ First shift the TOS element back to its final location.
SSSTTSSSSSSSSSSSSN    | PUSH 0x3000
TTT                   | LOAD
NSTTSTSN              | JSR > 1010 (stackrotate)
@ Now decrement the loop counter.
SSSTTSSSSSSSSSSSSN    | PUSH 0x3000
TTT                   | LOAD
SSSTN                 | PUSH 1
TSST                  | SUBTRACT
@ And check for the end of loop condition (counter < 2)
SNS                   | DUP
SSSTN                 | PUSH 1
TSST                  | SUBTRACT
NTSTSSTTSSTSSSSSTTSN  | BRZ > 10011001 00000110 (reverse_loop_end)
@ The loop continues. Store the new loop counter and go around again.
SSSTTSSSSSSSSSSSSN    | PUSH 0x3000
SNT                   | SWAP
TTS                   | STORE
NSNTSSTTSSTSSSSSTSTN  | JMP > 10011001 00000101 (reverse_loop)
@ End of loop. Clean up and continue.
NSSVTSSTTSSTSSSSSTTSN | MARK: 10011001 00000110 (reverse_loop_end)
SNN                   | DROP

@@@@@ Initialization complete. @@@@@

@ Stack now contains a list room numbers as integers, in order.

@ Put a loop index and the starting location of the arrow on the stack.
SSSTSSSSSSSSSTTSN     | PUSH 0x1006 (ptr to player_location, now arrow_location)
TTT                   | LOAD
SSSTSSSSSSSSSTSSN     | PUSH 0x1004 (ptr to max_arrow_flight_distance)
TTT                   | LOAD

@ TOS> loop_index, arrow_location, list_of_room_numbers ...
@ Move the arrow through a new room for each pass of the loop.
NSSVTSSTTSSTSSSSSTTTN | MARK: 10011001 00000111 (arrow_loop)
@ Check loop index for end of loop condition (index==0).
SNS                   | DUP
NTSTSSTTSSTSSSSTTSTN  | BRZ > 10011001 00001101 (loop_end)
@ Is the requested room number connected to the arrows current room?
SNT                   | SWAP
SNS                   | DUP
SSSTSSN               | PUSH 4
NSTTTSSN              | JSR > 1100 (deepdup)
NSTTSTSSTSSN          | JSR > 10100100 (are_rooms_adjacent)
NTSTSSTTSSTSSSSTSSSN  | BRZ > 10011001 00001000 (not_adjacent)
@ Room was adjacent. Print update for user, clean up stack and jump ahead.
SSSTTSSSSSSSSSSSSN    | PUSH 0x3000
SNT                   | SWAP
TTS                   | STORE
SNT                   | SWAP
SSSTTSSSSSSSSSSSTN    | PUSH 0x3001
SNT                   | SWAP
TTS                   | STORE
A"The arrow sails out of room %u and enters room %u.\n"
SSSTTSSSSSSSSSSSTN    | PUSH 0x3001
TTT                   | LOAD
SSSTTSSSSSSSSSSSSN    | PUSH 0x3000
TTT                   | LOAD
SSSTSN                | PUSH 2
NSTTSSSN              | JSR > 1000 (printf)
SSSTTSSSSSSSSSSSTN    | PUSH 0x3001
TTT                   | LOAD
SNT                   | SWAP
SSSTTSSSSSSSSSSSSN    | PUSH 0x3000
TTT                   | LOAD
SNT                   | SWAP
NSNTSSTTSSTSSSSTSSTN  | JMP > 10011001 00001001 (room_is_valid)
@ Room was not adjacent. Select a random adjacent room for the arrow.
NSSVTSSTTSSTSSSSTSSSN | MARK: 10011001 00001000 (not_adjacent)
SSSTTN                | PUSH 3
NSTTSTTN              | JSR > 1011 (stackrotatereverse)
@ TOS> (invalid) room_number, arrow_location, loop_index, rest_of_room_numbers ...
@ Start a message to the user.
@ First, store two values we will need when printing the user message.
SSSTTSSSSSSSSSSSSN    | PUSH 0x3000
SNT                   | SWAP
TTS                   | STORE
SSSTTSSSSSSSSSSSTN    | PUSH 0x3001
SNT                   | SWAP
TTS                   | STORE
A"*thunk* The arrow can't find a way from room %u to room %u "
SSSTTSSSSSSSSSSSSN    | PUSH 0x3000
TTT                   | LOAD
SSSTTSSSSSSSSSSSTN    | PUSH 0x3001
TTT                   | LOAD
SSSTSN                | PUSH 2
NSTTSSSN              | JSR > 1000 (printf)
@ Now locate a random, connected room for the arrow to visit.
NSTTSSSSN             | JSR > 10000 (random)
SSSTSSSSSSSSSSTTN     | PUSH 0x1003 (ptr to number_of_tunnels_per_room)
TTT                   | LOAD
TSTT                  | MODULO
SSSTTSSSSSSSSSSSTN    | PUSH 0x3001
TTT                   | LOAD
NSTTSSSTSSSN          | JSR > 10001000 (get_tunnel_destination)
@ Now finish the message to the user.
SSSTTSSSSSSSSSSSSN    | PUSH 0x3000
SNT                   | SWAP
TTS                   | STORE
A"and flys randomly into room %u!\n"
SSSTTSSSSSSSSSSSSN    | PUSH 0x3000
TTT                   | LOAD
SSSTN                 | PUSH 1
NSTTSSSN              | JSR > 1000 (printf)
@ And cleanup the stack before continuing onward.
SSSTTSSSSSSSSSSSSN    | PUSH 0x3000
TTT                   | LOAD
SNT                   | SWAP
SSSTTSSSSSSSSSSSTN    | PUSH 0x3001
TTT                   | LOAD
SNT                   | SWAP

NSSVTSSTTSSTSSSSTSSTN | MARK: 10011001 00001001 (room_is_valid)
@ TOS> loop_index, arrow_location, list_of_room_numbers ...
SSSTTN                | PUSH 3
NSTTSTSN              | JSR > 1010 (stackrotate)
SNN                   | DROP
@ TOS> (new) arrow_location, loop_index, (smaller) list_of_room_numbers ...
@ Does new room contain a wumpus?
SNS                   | DUP
NSTTSTSSSSSN          | JSR > 10100000 (room_has_wumpus)
NTSTSSTTSSTSSSSTSTSN  | BRZ > 10011001 00001010 (no_wumpus_here)
@ Player slew the wumpus!
NSTTTTTTTTTSSSSSSSTN  | JSR > 11111111 00000001 (kill_wump)
SSSSN                 | PUSH 0
NSTTSSSN              | JSR > 1000 (printf)
NNN                   | DIE
@ No wumpus here. Does the new room contain the player?
NSSVTSSTTSSTSSSSTSTSN | MARK: 10011001 00001010 (no_wumpus_here)
SNS                   | DUP
SSSTSSSSSSSSSTTSN     | PUSH 0x1006 (ptr to player_location)
TTT                   | LOAD
TSST                  | SUBTRACT
NTSTSSTTSSTSSSSTSTTN  | BRZ > 10011001 00001011 (player_shot_self)
NSNTSSTTSSTSSSSTTSSN  | JMP > 10011001 00001100 (no_events_in_room)
NSSVTSSTTSSTSSSSTSTTN | MARK: 10011001 00001011 (player_shot_self)
@ Player hit by own arrow!
NSTTTTTTTTTSSSSSSTTN  | JSR > 11111111 00000011 (shoot_self)
SSSSN                 | PUSH 0
NSTTSSSN              | JSR > 1000 (printf)
NNN                   | DIE
@ No player here. Update loop index, cleanup stack and loop again.
NSSVTSSTTSSTSSSSTTSSN | MARK: 10011001 00001100 (no_events_in_room)
SNT                   | SWAP
SSSTN                 | PUSH 1
TSST                  | SUBTRACT
NSNTSSTTSSTSSSSSTTTN  | JMP > 10011001 00000111 (arrow_loop)
NSSVTSSTTSSTSSSSTTSTN | MARK: 10011001 00001101 (loop_end)
SNN                   | DROP
SNN                   | DROP
A"The arrows wavers in its flight and can go no further!\n"
SSSSN                 | PUSH 0
NSTTSSSN              | JSR > 1000 (printf)

@ Since the player did not kill the wumpus, there is a chance it will wake and move.
NSTTSSSSN             | JSR > 10000 (random)
SSSTTSN               | PUSH 6
TSTT                  | MODULO
NTSTSSTTSSTSSSSTTTSN  | BRZ > 10011001 00001110 (move_wumpus)
NSNTSSTTSSTSSSTSSSSN  | JMP > 10011001 00010000 (wumpus_continues_to_slumber)
NSSVTSSTTSSTSSSSTTTSN | MARK: 10011001 00001110 (move_wumpus)
@ Move the wumpus to a random connected room.
NSTTSSSSN             | JSR > 10000 (random)
SSSTSSSSSSSSSSTTN     | PUSH 0x1003 (ptr to number_of_tunnels_per_room)
TTT                   | LOAD
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
@ Did the wumpus enter the player room?
SSSTSSSSSSSSSTTTN     | PUSH 0x1007 (ptr to wumpus_location)
TTT                   | LOAD
SSSTSSSSSSSSSTTSN     | PUSH 0x1006 (ptr to player_location)
TTT                   | LOAD
TSST                  | SUBTRACT
NTSTSSTTSSTSSSSTTTTN  | BRZ > 10011001 00001111 (player_death)
NSNTSSTTSSTSSSTSSSSN  | JMP > 10011001 00010000 (wumpus_continues_to_slumber)
NSSVTSSTTSSTSSSSTTTTN | MARK: 10011001 00001111 (player_death)
NSTTTTTTTTTSSSSSSSSN  | JSR > 11111111 00000000 (wump_kill)
SSSSN                 | PUSH 0
NSTTSSSN              | JSR > 1000 (printf)
NNN                   | DIE

NSSVTSSTTSSTSSSTSSSSN | MARK: 10011001 00010000 (wumpus_continues_to_slumber)
@ Decrement the number of arrows.
SSSTSSSSSSSSSTSTN     | PUSH 0x1005 (ptr to number_of_arrows)
TTT                   | LOAD
SSSTN                 | PUSH 1
TSST                  | SUBTRACT
SNS                   | DUP
SSSTSSSSSSSSSTSTN     | PUSH 0x1005 (ptr to number_of_arrows)
SNT                   | SWAP
TTS                   | STORE
@ Check for empty quiver.
NTSTSSTTSSTSSSTSSSTN  | BRZ > 10011001 00010001 (empty_quiver)
NTN                   | RTS
NSSVTSSTTSSTSSSTSSSTN | MARK: 10011001 00010001 (empty_quiver)
NSTTTTTTTTTSSSSSSTSN  | JSR > 11111111 00000010 (no_arrows)
SSSSN                 | PUSH 0
NSTTSSSN              | JSR > 1000 (printf)
NNN                   | DIE

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ 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)
NSTTSSTTSSTN          | JSR > 10011001 (shoot_arrow)
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"\n----------\n\nYou 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

#endif