SNES format

This file describes the format of data in PoP1 for SNES.

This document is far from complete. I will continuously add information to it.

The resource tables

There are 3 resource tables in the ROM, at the following addresses:

Address	Count	Contents
0x20000	91 or 92	Levels, Graphics
0x78000	1485	Sprites
0xE8000	36 or 37	Sounds, Musics

A resource table is an array of addresses. Each address is in the following form: A word telling the offset and a byte telling the segment (also called "bank"). Segments are in the range 0x00..0x1F, offsets are in the range 0x8000..0xFFFF. address=segment*0x8000+offset-0x8000

e.g. 0x14 0x81 0x04 means offset=0x8114, segment=0x04, address=0x04*0x8000+0x0114=0x20114 Note that some ROM images have a 0x200 byte header.

The size or type of the resource is not stored.

Contents of the first resource table: (0x20000)

00: menu/intro font
01..40: the 10 enviroments
	(each type has four resources: background, blocks background, blocks foreground, palette)
	0: 01,02,03,04: blue dungeon
	1: 05,06,07,08: pink palace
	2: 09,10,11,12: grey palace
	3: 13,14,15,16: red dungeon
	4: 17,18,19,20: green palace
	5: 21,22,23,24: brown dungeon
	6: 25,26,27,28: red palace
	7: 29,30,31,32: level 20
	8: 33,34,35,36: jaffar
	9: 37,38,39,40: demo red palace
41..67: the 27 levels: level 1-20, jaffar, demo, training 1-5
68: sprite palettes
69: screen palettes
70: hitpoint tiles
71: princess room screen
72: princess room arches screen
73: torch tiles
74: ending font
75: Masiya logo screen
76: stars screen (big)
77: torture screen (big)
78: garden screen (big)
79: title screen
80: title things screen
81: pattern screen
82: game name screen
83: main menu background screen
84: where Jafar walks screen (big)
85: ending: prince at sultan screen
86: ending: prince and princess at window with people screen
87: ending: prince and princess at window with sundown screen
88: ending: sundown screen
89: ending: sundown 2 screen
90: Japanese characters screen
91: Konami logo screen (Europe/USA versions only)

Contents of the second resource table: (0x78000)

0000..1248: regular sprites

1249..1394: sprites that are put into the background (traps, buttons, doors), 48*64 pixels

1395..1484: masks, 48*64 pixels

Contents of the third resource table: (0xE8000)

(needs description)

Resource formats

Tiles

The SNES uses planar tiles, which can be 2- or 4-bit.

(needs further description)

Palettes

The SNES uses 5:5:5 RGB palettes, each entry is a word in the following format:

0bbbbbgggggrrrrr

Environments

(needs description)

Levels

Levels are compressed.

I'll try to explain the algorithm:

procedure decompress_a_part(input:stream of bytes,output:stream of bytes,LEN:integer)
 clear output
 repeat while you don't have LEN bytes in the output:
  read a byte to X
  if X>=128 then
   copy X-128 bytes from input to output
  else
   read a byte to Y, if Y=0 then Y:=256
   if X=1: read a byte to D, write D to output Y times
   if X=2: read a byte to D, write D,D+1,D+2,... to output, Y bytes total
   if X=3: read a byte to D, write D,D-1,D-2,... to output, Y bytes total
   if X=4: read a byte to A, copy Y bytes from the A-th byte of the output to after the end of the output
   if X=5: read a 2-byte integer to A, copy Y bytes from the A-th byte of the output to after the end of the output
   // note that the source and destination may overlap in the above two cases
   otherwise: error
  end if
 end repeat
end procedure

You have to call the above procedure with these values of LEN, and concatenate the outputs: 720,720,720,256,256,256,256,244,256,256
Each input part begins directly after the end of the previous.
Calling with LEN=3940 at once won't work, because at the X=4 and X=5 cases, A is counted from the beginning of the current part, not the beginning of the whole level data.

Parts of the level:

Size  Contents
--------------
720   background layer
720   blocks layer
720   modifiers layer
256   block layer 1 graphics
256   block layer 2 graphics
256   block objects
256   block flags
244   room links, starting position, guards
256   door events 1
256   door events 2

Background layer

One byte for each tile. Selects which background graphics should be used for this tile.

Blocks layer

One byte for each tile. Selects which block should be used for this tile.

Informations about blocks are found in the four parts whose names begin with "block".

Some blocks are used for special purposes:

Block 255 is used for nonexistent rooms. (Room link=255) It is usually a wall.

Block 254 is used for buttons that are permanently triggered by a dead guard or loose floor. It is usually a floor.

Reason: Button blocks don't have floor graphics, because the button object draws it for them.

If a button is triggered permanently, it needs to be changed into a regular floor, which does need floor graphics.

The only way this can be done is placing a different block into the place of the button.

Modifiers layer

One byte for each tile. Selects which modifier should be used for this tile.

Its meaning depends on the object used.

Block layer 1 graphics

One byte for each block type. Selects which background graphics should be used for this block type.

Block layer 2 graphics

One byte for each block type. Selects which foreground graphics should be used for this block type.

Block objects

One byte for each block type. Selects which object should be used for this block type.

value	object type
---------------------
0x00	(none)
0x01	(unused)
0x02	loose floor
0x03	(unused)
0x04	open button
0x05	close button
0x06	door
0x07	leveldoor end
0x08	mirror
0x09	skeleton
0x0A	sword
0x0B	torch
0x0C	chomper
0x0D	guillotine
0x0E	spike
0x0F	(unused)
0x10	crusher
0x11	(unused)
0x12	heal potion
0x13	life potion
0x14	hurt potion
0x15	upside down potion
0x16	slow fall potion
0x17	debris
0x18	door top
0x19	fire
0x1A	potion of warp
0x1B	down only
0x1C	kill potion
0x1D	torch
0x1E	spinning log
0x1F	(unused)
0x20	stars
0x21	torch
0x22	torch
0x23	teleport
0x24	leveldoor begin
0x25	(unused)
0x26	(unused)
0x27	lava
0x28	skeleton continue
0x29	skull?
0x2A	conveyor belt >>>
0x2B	conveyor belt <<<

Notes:

There are four torch objects. They differ in the position of the flames.

The potion of warp will take the player to room 17, tile 11, turned left.

"skeleton continue" means that if a skeleton falls into this room then it will appear here.

"down only": if added to a block that has floor, the player can fall through it, but can't jump/climb up through it.

If the modifier is in the 1..4 range, the transparent floor you can see after the shadow fight will appear.

Lava: falling onto this tile from any height will kill the prince.

Meaning of the modifier for each object:

For the loose floor, chomper, guillotine, spike, crusher, down only, spinning log, stars objects,

the modifier selects the animation frame to be displayed. It should be zero.

For the open and close buttons, the modifier selects the door event to be triggered.

For doors, the modifier specifies how much the door is open, in 1/4 pixels.

Teleports: Entering a teleport will take to the other teleport with the same modifier.

Block flags

One byte for each block type. Determines if the current block type is a floor or a wall.

If bit 0 is set then this block type is a floor.

If bit 1 is set then this block type is a wall.

The meaning of other bits (if any) is unknown.

Room links, starting position, guards

Size  Contents
--------------
24*4  Room links
1     Starting room
1     Starting position in room
1     Starting direction
1     unused
24    Guard position in room
24    Guard type and direction
4*24  unknown

Room links: For every room, the room to the left, right, above and below the current room is given, in this order.

The rooms are numbered 0..23.

255 means that no room is in the given direction.

For the "above" link, 254 means the same, plus that the 4-pixel part of the room above (which would have walls) is not shown.

This is used for special "outdoor" rooms.

Note: rooms are numbered 0..23, which is different from the DOS version.

Starting room: The room the player starts in. Can be 0..23.

Starting position in room: row*10+column. (0..29)

Starting direction: 0xFF=left, 0x00=right.

Guard position in room: row*10+column (0..29), or 0xFF if there is no guard in this room.

Guard type and direction: The bottom 7 bits specify the guard type, the top bit specifes the direction. 1=left, 0=right.

value	guard type
---------------------
0x02	dead purple
0x03	skeleton
0x04	brown skeleton
0x05	golden skeleton
0x06	girl
0x07	fat
0x08	shadow
0x09	green
0x0A	greenish blue
0x0B	blue
0x0C	red
0x0D	purple
0x0E	blueface
0x0F	red knight
0x10	blue knight
0x11	monster
0x12	Jaffar
0x13	dead

Other values may display garbage or may even hang the game.

Door events 1 and 2

(same format as in DOS version)
-------------------------  7  6  5  4  3  2  1  0 <-bits
byte from door events 1 | NX R1 R0 L4 L3 L2 L1 L0
byte from door events 2 | R4 R3 R2  0  0  0  0  0

R4 R3 R2 R1 R0: The number of the room. (0..23)

L4 L3 L2 L1 L0: The location in the room. (0..29)

NX: If zero then trigger next door event, if one then don't.

Screens

Screens are compressed.

(needs further description)

screen=32*28 tiles

big screen=64*56 tiles

Sprites

Sprites are compressed.

(needs further description)

Musics

(needs description)