Decoded: Rogue (1980) by Toy, Arnold, Wichman
DOS version (1983) by Mel Sibony and Jon Lane
Source file: WEAPONS.C
Beginner friendly, line-by-line code walkthrough by MaiZure

WEAPONS.C provides weapon usage, item drop, and missile flight functions

Original code:
https://britzl.github.io/roguearchive/

Original code with line numbers
http://www.maizure.org/projects/decoded-rogue/WEAPONS_linenum.txt



1     COMMENT
2     COMMENT
3     COMMENT
4     COMMENT
5     COMMENT
6     BLANK
7     Include game header
8     Include console management header
9     BLANK
10    Defines a placeholder value to tag non-projectile weapons
11    BLANK
12    Declares a weapon statistic structure
13    Wielding damage
14    Thrown damage
15    Launcher type
16    Other weapon flags
17    Initialize statistics for all 10 weapon types
18    Mace statistics
19    Long sword statistics
20    Bow statistics
21    Arrow statistics
22    Dagger statistics
23    Two-handed sword statistics
24    Dart statistics
25    Crossbow statistics
26    Crossbow bolt statistics  
27    Spear statistics
28    End of weapon statistic definitions
29    BLANK
30    COMMENT
31    COMMENT
32    COMMENT
33    COMMENT

SHOOT PROJECTILE

34    Defines missile with two arguments
35    Arguments 1 and 2 are the change in x and y per step (direction)
36    BLOCK START - missile, launches a projectile
37    Declare pointers to the object being launched and new copies of objects
38    BLANK
39    COMMENT
40    COMMENT
41    COMMENT
42    If the player fails to choose a weapon to shoot
43    Return failure
44    If the player chooses their current worn weapon or it's cursed
45    Return failure
46    COMMENT
47    COMMENT
48    COMMENT
49    COMMENT
50    COMMENT
51    Create a label to jump back and repeat a check
52    If there is only 1 item of the type in inventory...
53    Remove the item from inventory
54    Decrement the inventory counter
55    Otherwise this is a stack we're shooting (usually arrows/bolts)
56    COMMENT
57    COMMENT
58    COMMENT
59    Create a new item but if it fails...
60    Set the existing item stack to 1
61    Print a failure message
62    Redo from line 51, which will succeed now
63    End check for item creation failure
64    Decrement the stack counter
65    If the item is not in a group (not in inventory)  
66    Decrement inventory counter
67    Copy the old object to the new object
68    Set the new object's count to 1 (only shoot 1 item at a time)
69    Reset the shooting object to the new item
70    End check for shooting from a multi-item stack
71    Animate the shot
72    COMMENT
73    COMMENT
74    COMMENT
75    COMMENT
76    If there is no monster at the item's position after animation..
77    Or the item isn't covering a monster (Same thing?)
78    The item should fall to the ground
79    BLOCK END - missile
80    BLANK
81    COMMENT
82    COMMENT
83    COMMENT
84    COMMENT
85    COMMENT

ANIMATE MISSILE

86    Defines do_motion with three arguments
87    Argument 1 is the pointer to an object
88    Arguments 2 and 3 are the direction deltas
89    BLOCK START - do_motion, animates projectiles
90    Declare a dud value for the floor position under the projectile
91    BLANK
92    COMMENT
93    COMMENT
94    COMMENT
95    Copy the player's position in to the object's position
96    Loop forever
97    Declare an integer used as a floor character
98    BLANK
99    COMMENT
100   COMMENT
101   COMMENT
102   If the projectile has moved, isn't at the player, but player can see it
103   Draw the floor character in place (remove projectile for new movement)
104   COMMENT
105   COMMENT
106   COMMENT
107   Update the projectile's y
108   Update the projectile's x
109   BLANK
110   If the projectile is in an open space and not at a doorway...
111   COMMENT
112   COMMENT
113   COMMENT
114   COMMENT
115   If the player can still see the projection
116   Save the floor character at the updated position
117   Draw the projectile on the map
118   Wait a tick
119   Otherwise, player can't see it anymore
120   Save the dud character since we won't be updating drawing anymore
121   Continue to next step
122   End check for projectile in an open space
123   Break from loop -- projectile stopped or travelled out of sight
124   Repeat infinite loop
125   BLOCK START - do_motion
126   BLANK

GET ITEM SHORT NAME

127   short_name returns a pointer to a string
128   Defines short_name with one argument
129   Argument 1 is the input object
130   BLOCK START - short_name, returns the brief name (item type)
131   Switch on object type
132   CASE weapon: return the basic value from the weapon name table
133   CASE armor:  return the basic value form the armor name table
134   CASE food: just return the string 'food'
135   CASE potion (fallthrough)
136   CASE scroll (fallthrough)
137   CASE amulet (fallthrough)
138   CASE wand/staff (fallthrough)
139   CASE ring
140   Return the name as shown in inventory
141   For all other object types (there aren't any...)
142   Return an unknown type string
143   End switch on object type
144   BLOCK END - short_name
145   BLANK
146   COMMENT
147   COMMENT
148   COMMENT
149   COMMENT

ITEM DROP

150   Defines fall with two arguments
151   Argument 1 is the object to drop
152   Argument 2 is a flag to destory on drop
153   BLOCK START - fall, drops an item around around a location
154   Declare a fall coordinate
155   Declare a level position index
156   BLANK
157   Switch on the calculated fall position
158   BLOCK START - Switch on fall position
159   CASE regular fall to floor
160   Get the position within the level data array
161   Set the level data to the new object
162   Copy the position data to the object
163   If the player can see the object...
164   BLOCK START - Update player view after drop
165   If the object was dropped in a passage...
166   or a maze...
167   Apply highlighted text (inverted colors)
168   Draw the character
169   End extended formatting
170   If there is a monster at the dropped position
171   Update the monster's character buffer to the object it's now standing
      on
172   BLOCK END - Update player view after drop
173   Add the object to the level's object data
174   Return success
175   CASE fall in to a stack
176   No reason to destroy it - it was added to a floor stack
177   BLOCK END - Switch on fall position
178   If the destroy flag was set...
179   Print a message
180   and possibly an extended message
181   Remove the temp object from memory
182   BLOCK END - fall
183   BLANK
184   COMMENT
185   COMMENT
186   COMMENT
187   COMMENT

INITIALIZE WEAPON OBJECT

188   Defines init_weapon with two arguments
189   Argument 1 is a pointer to a weapon
190   Argument 2 is a weapon type
191   BLOCK START - init_weapon, initializes weapon variables
192   Declare a pointer to the weapon statistics table
193   BLANK
194   Get the base weapon from the weapon table
195   Set the new weapon's damage from the table
196   Set the new weapon's hurl damage from the table
197   Set the new weapon's launcher type from the table
198   Set the new weapon's flags from the table
199   If the weapon is part of a stack (Arrows, etc)
200   BLOCK START - weapon stack
201   Add a randon stack size between 8 and 15
202   Add the weapon to a group
203   BLOCK END - weapon stack
204   Otherwise this is a single weapon
205   Count is one
206   BLOCK END - init_weapon
207   BLANK
208   COMMENT
209   COMMENT
210   COMMENT
211   COMMENT

PROJECTILE HIT

212   Defines hit_monster with three arguments
213   Arguments 1 and 2 are position values
214   Argument 3 is a pointer to an object
215   BLOCK START - hit_monster, detects missile hit and applies damage
216   Declare a static coordinate (stays the same between calls)
217   Declare a pointe rto a monster
218   BLANK
219   If there is a monster at the input position...
220   Set the y coordinate
221   Set the x coordinate
222   Apply the projectile fight result to the monster
223   End check for monster at position
224   Return false - nothing hit
225   BLOCK END - hit_monster
226   BLANK
227   COMMENT
228   COMMENT
229   COMMENT
230   COMMENT

CALCULATE WEAPON AUGMENTATION VALUES

231   num returns a pointer to a string of a value
232   Declare num with three arguments
233   Arguments 1 and 2 are statistic values 1 = Armor stat, 2 = weapon stat
234   Declares the type of number, armor or weapon values
235   BLOCK START - num, calculates the additional damage/protect description
236   Declare an output text buffer
237   BLANK
238   Get the augment sign, none or positive
239   If this is a weapon...
240   Use the second argument
241   Return the output description
242   BLOCK END - num
243   BLANK
244   COMMENT
245   COMMENT
246   COMMENT
247   COMMENT

WIELD A WEAPON

248   Declares wield with no arguments
249   BLOCK START - wield, wears a weapon
250   Declares pointers to two objects, one wearing and one to be worn
251   Delcares a pointer to a string
252   BLANK
253   Get the current weapon
254   If player can't drop the current weapon...
255   BLOCK START - Cursed weapon
256   Keep the current weapon as the already worn choice
257   Return failure to wield
258   BLOCK END - Cursed weapon
259   Keep the current weapon as the already worn choice
260   If the player didn't choose a weapon to wield...
261   BLOCK START - Failed wield
262   Label to bad wield attempts
263   Do not pass time
264   Return failure
265   BLOCK END - Failed wield
266   BLANK
267   If the object to wield is armor
268   BLOCK START - Can't wield armor
269   Print failure message
270   Jump to bad wield on line 262
271   BLOCK END - Can't wield armor
272   If the chosen weapon is already worn
273   Return - nothing to do
274   BLANK
275   Otherwise, we've passed all checks - get the item's name
276   Set the item as the current weapon
277   Print success message
278   BLOCK END - wield
279   BLANK
280   COMMENT
281   COMMENT
282   COMMENT
283   COMMENT

FIND DROP POSITION

284   Declare fallpos with two arguments
285   Argument 2 is the coordinate to return
286   Argument 1 is object to search around for a position
287   BLOCK START - fallpos, gets the fall position offset from a fixed point
288   Declare position position iterators, a character, and init a counter
289   Declare a pointer to a floor object
290   BLANK
291   Loop through all rows around the input object (top to bottom)
292   Loop through all columns around the input object (left to right)
293   COMMENT
294   COMMENT
295   COMMENT
296   COMMENT
297   COMMENT
298   If the player is at the identified position or it's off the map..
299   Skip this position
300   If the character at the position is floor or passage (it's available)
301   Count the position and roll a random check starting at 50%
302   Set the y position of the drop 
303   Set the x position of the drop
304   End check for choosing this drop position (Upper-left drop is favored)
305   Skip to next check
306   End check for empty space
307   If it's possible for the player to step on this position
308   And there's an object on the floor
309   And the object type matches the input object type
310   And the floor object has an item group
311   And the item groups match...
312   BLOCK START - Add dropping object to a stack
313   Add to the floor objects count
314   Return 2
315   BLOCK END - Add dropping object to a stack
316   End loop through adjacent positions
317   Return false if no positions are possible
318   BLOCK START - fallpos
319   BLANK

BLOCK DURING TICK

320   Defines tick_pause with no arguments
321   BLOCK START - tick_pause, blocks processing during the same tick
322   Declare a variable to save the current tick
323   Import the actual current tick
324   BLANK
325   Match the tick counter...
326   While the ticks are the same (interrupt-driven update)
327   Loop forever
328   BLOCK END - tick_pause
329   EOF˙