Prehistorik Level Format

Prehistorik Level Format

File:Prehistorik Level Format.png
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Format type	Map/level
Map type	2D tile-based
Layer count	2
Tile size (pixels)	16×16
Viewport (pixels)	320×200
Games	Prehistorik

Prehistorik stores its level data inside the historik.exe file.

File format

Secret teleporter locations indicated in red.

The level information is stored in such an awkward way that it is practically unmoddable. Each level has its own (mostly copy-pasted) code routine with a lot of hardcoded behaviour. For example, level 1 is the only level with secret areas; the first one is at the jumping fish (screen 6, counted from the start, not using the in-game data screen number), and the second one at the third screen after landing; just left of a ladder leading down to water (screen 14, again, counted from the start). The wrap areas for those screens are hardcoded in the code routine for the first level. Other levels simply don't have this code, meaning any attempts to add secret screens to them is futile.

All the address location information provided below is for the floppy version. On the CD-ROM version (included in GoG/Steam release) the locations are offset but correlatable to the locations on the floppy version.

Location of the level routines in historik.exe file:

• Level1: 0x00013F9F
• Level3: 0x00014E52
• Level5: 0x0001567C
• Level7: 0x00017D2B

Each level screen is split into a few separate structures. Here are a few of them:

Level	Count	Heights (offs)	Sizes (offs)	Data (offs)
1	19	0x00021668	0x00021A06	0x00021A2E
3	19	0x000216C6	0x0002333A	0x00023362
5	19	0x00021738	0x000247BA	0x000247E0
7	19	0x000219AE	0x000257C6	0x000257EE

Each screen is an independent list of objects, starting at (0, 0) as the top-left corner of the screen. At Data offset located Count screens with Sizes+1 records (xPos, yPos, type) each.

Note that Height and Sizes are actually UINT16LE lists of Count items and Height is a level height in pixels (0..199) where death trigger located - for screens with bottomless pits it's usually 199, but the number is less for screens with secret area teleports or higher grounds.

! Spikes, cave entrances, hidden bonuses and other things

Each screen within a level is comprised of the following structure, repeated once for each object in the level.

Data type	Name	Description
INT16LE	xPos	X location of the object
INT16LE	yPos	Y location of the object, in pixels from the top of the screen
UINT16LE	nTile	Background tile element number from the corresponding ELEML#.MAT for the level (where # is a level number)

This structure is repeated Sizes+1 times until the end of the current screen.

nTile types

Each nTile value in the structure above is as follows: ! This list is incomplete - and seems to match the sprites in eleml1.mat as extract by Wombat

Code	Description
0x00	Trampoline! Causes strange behaviour though
0x01	Left ledge (earth)
0x02	Square block (earth)
0x03	Right ledge (earth)
0x04	Rock sign: "level 1"
0x05	Rock wall left ledge
0x06	Rock wall solid rectangle
0x07	Rock wall right ledge
0x08	Block of water with waves (background)
0x09	Rock wall with cave entry
0x0A	Ladder
0x0B	Green line?
0x0C	Green line?
0x0D	Pine tree
0x0E	! TODO
0x0F	Different water with waves (background)
0x10	Palm tree
0x11	Underwater bubbles background
0x12	Underwater bubbles background #2
0x13	Underwater bubbles background #3
0x14	Green line?
0x15	Bush/shrubbery
0x16	Rock wall solid rectangle (without walkable top)
0x17	Cave background right
0x18	Cave background middle
0x19	Dinosaur

Level parsing example source code

C

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>

/*
  (c) CTPAX-X Team 2019,2020
  http://www.CTPAX-X.org/

  you can redirect output from this tool to the text file:
  hmapinfo > hist_map.txt
*/

/* scr_count, heights, sizes, scr_offs */
static uint32_t levels[4][4] = {
  {19, 0x00021668, 0x00021A06, 0x00021A2E},
  {19, 0x000216C6, 0x0002333A, 0x00023362},
  {19, 0x00021738, 0x000247BA, 0x000247E0},
  {19, 0x000219AE, 0x000257C6, 0x000257EE}
};

int main(void) {
FILE *fl;
uint16_t sz[20], ht[20];
int16_t item[3];
int32_t i, j, k;
  fl = fopen("HISTORIK.EXE", "rb");
  if (!fl) {
    printf("Error: can't open \"HISTORIK.EXE\" file.\n\n");
    return(1);
  }

  for (k = 0; k < 4; k++) {
    printf("*** Level-%d\n", (k*2) + 1);
    /* heights */
    fseek(fl, levels[k][1], SEEK_SET);
    fread(ht, 2, levels[k][0], fl);
    /* sizes */
    fseek(fl, levels[k][2], SEEK_SET);
    fread(sz, 2, levels[k][0], fl);
    /* calculate total records number for all screens at level */
    j = 0;
    for (i = 0; i < levels[k][0]; i++) {
      printf("%2d ", sz[i] + 1);
      j += sz[i];
    }
    printf("\nRecords: %d\n", j);
    /* for each screen */
    fseek(fl, levels[k][3], SEEK_SET);
    for (i = 0; i < levels[k][0]; i++) {
      printf("== SCR-%02d | height: %d\n", i + 1, ht[i]);
      for (j = 0; j < sz[i] + 1; j++) {
        fread(item, 3, 2, fl);
        printf("OBJ# %3d at %3d,%3d\n", item[2], (item[0] / 16) * 16, item[1]);
      }
      printf("\n");
    }
    printf("FilePos: %lX\n\n\n", ftell(fl));
  }

  fclose(fl);
  return(0);
}

Credits

This file format was reverse engineered by KeenRush. If you find this information helpful in a project you're working on, please give credit where credit is due. (A link back to this wiki would be nice too!)