; **************************************************************************** ; star97pm.s (TRDOS 386, TRDOS v2.0 - sample binary file, 'star97pm.prg') ; ---------------------------------------------------------------------------- ; STAR97PM.PRG ! TEST program ! TRDOS 386 VGA Functionality test ! ; ; 03/10/2016 ; ; [ Last Modification: 03/10/2016 ] ; ; Derived from source code of 'STAR97.COM' (MSDOS) intro file ; (Source: STAR97.ASM, 15/05/1997, 97 bytes) ; ; STAR97.ASM by Deathlock / Assembler (TASM4) ; NASM version of STAR97.ASM: Erdogan Tan, 02/10/2016 (star97.s) ; ; Assembler: NASM 2.11 ; ; (Original -msdos- code has been modifed for TRDOS 386 system calls and ; other protected mode (TRDOS 386) interrupts.) ; **************************************************************************** ; 19/05/2016 ; 29/04/2016 ; TRDOS 386 system calls (temporary list!) _ver equ 0 _exit equ 1 _fork equ 2 _read equ 3 _write equ 4 _open equ 5 _close equ 6 _wait equ 7 _creat equ 8 _link equ 9 _unlink equ 10 _exec equ 11 _chdir equ 12 _time equ 13 _mkdir equ 14 _chmod equ 15 _chown equ 16 _break equ 17 _stat equ 18 _seek equ 19 _tell equ 20 _mount equ 21 _umount equ 22 _setuid equ 23 _getuid equ 24 _stime equ 25 _quit equ 26 _intr equ 27 _fstat equ 28 _emt equ 29 _mdate equ 30 _video equ 31 _audio equ 32 _timer equ 33 _sleep equ 34 _msg equ 35 _geterr equ 36 _rsrvd1 equ 37 _pri equ 38 _rele equ 39 %macro sys 1-4 ; 29/04/2016 - TRDOS 386 (TRDOS v2.0) ; 03/09/2015 ; 13/04/2015 ; Retro UNIX 386 v1 system call. %if %0 >= 2 mov ebx, %2 %if %0 >= 3 mov ecx, %3 %if %0 = 4 mov edx, %4 %endif %endif %endif mov eax, %1 ;int 30h int 40h ; TRDOS 386 (TRDOS v2.0) %endmacro ; TRDOS 386 (and Retro UNIX 386 v1) system call format: ; sys systemcall (eax) , , ; STAR97.S (NASM version of STAR97.ASM) ; ; [ STARFIELD '97 ] ; ; [ Explanation ] ; ; well, here's an explanation of what's going on. first off we generate the ; starfeild data, star structures are qword aligned for easy offset calc's, ; and a floating random number seed is used. the initial random seed is mov'd ; into the very last star structure, and the next random seed is stored in ; the structure below, and this routine is followed to the very first star ; structure. instead using the modulus of the random number and using it as ; the saved value we mask off all the unwanted bits in the random number, and ; then modify the values to fit in the ranges we need. i was looking for a 4 ; layer field (00000011b), and 16 scales of white (00001111b). nifty both ; numbers are binary constants, lucky me! most things don't work out so well. ; ; [ Excuses ] ; ; ok, your saying "Big woop!, i've seen 20 byte starfields". well this is ; true, so have i. however all those starfields are just random color shit. ; not only is the randomness shitty, but they don't check for a keypress, and ; they don't even look like a starfield, otherwise there not usable at all! ; this routine has parallax style scrolling of a 4 layer starfield, 16 random ; shades of stars, a fairly random placement of stars, it's fast, and it even ; checks for vertical retrace and keypress! ; ; [ Questions / Answers ] ; ; you may be scratching your head on some of the sections of this code, so ; let me give you my reasoning before you call me a dumbshit. ; ; Q: why don't you use 'in ax,40h' as a random number routine rather than ; using imul and such? ; ; A: well 'in ax,40h' sucks, it's not random enough, try it. you'll see my ; reasoning, the method used is much better. btw i got the random routine ; i'm using by simplifying the random routine used by borland turbo c 3.0 ; i just disassembled the lib call and this is pretty much what i got. ; otherwise i had no idea how to make random numbers, this concept was new ; to me!, wow a learning experience. ; ; Q: why don't you use a 4 byte structure, a word for the address, and a byte ; for the speed, and another byte for the color? ; ; A: well in the main loop you'll see that i add the speed to the address, ; and that i store the address in di, well this means that if i wanted to ; add anything to a 16bit register i would have to use another 16bit mem ; location or register, and i can't otherwise it screws up. i wish there ; was some kind of addzx instruction which added the contents of a smaller ; register but internally masked it to the same size as the destination ; with zero's extended. ohh well there are too many instructions anyways. ; ; Q: only 255 stars? ; ; A: it looks ok doesn't it?!, you can use up to something like 8000 stars if ; you change the 'mov cl,NSTARS' to 'mov cx,NSTARS'. however the code size ; will increase two bytes (this was my origional goal 99 bytes), however i ; was told it would be "cooler" to release something that referenced the ; current year?? ; ; Q: my god your a moron, i could make this much smaller, and still retain ; all of the kewl features you talk about. ; ; A: great, please do, and send me your changes to brandt@europa.com. i tried ; to the best of my ability to make it smaller, i even got it to 87 bytes ; using the 'in ax,40h', and commenting out the random number seed setup, ; and the imul, along with the following mov. but like i said a couple of ; questions above 'in ax,40h' looks shitty. ; ; ohh, one last thing i do use the following 80386 instructions: ; ; shl reg16,immediate > 1 ; imul reg16,mem | reg16,reg16 | immediate ; ; deathlock ; brandt@europa.com ; NASM version: Erdogan Tan, 03/10/2016 NSTARS EQU 255 ; number of stars to draw [Bits 32] ; Protected Mode (TRDOS 386) Program [org 0] ; TRDOS 386 PRG File start: ; DIRECT VGA MEMORY ACCESS ;xor ebx, ebx mov bh, 5 ; Direct access/map to VGA memory (0A0000h) ;mov eax, _video ; 1Fh mov al, 1Fh ; sys _video ; TRDOS 386 Video functions int 40h ; TRDOS 386 system call ; eax = 0A0000h and eax, eax jz terminate ; error (eax = 0) mov edi, eax ; 0A0000h ; es = 0A000h ; VGA memory (frame buffer) address mov al,13h ; function 00h, mode 13h ;int 10h ; bios video interrupt int 31h ; TRDOS 386 - Video interrupt ;[ initialize starfield variables ]------------------------------------------ mov cl,NSTARS ; cx = number of stars to initialize mov byte [NSTARS*8+stars+8],1 ; set the begining random number seed loop1: mov bx,cx ; copy cx to bx for indexing shl bx,3 ; multiply bx by 8 (structure size) add bx,stars ; add the start offset of stars to bx imul ax,word [ebx+8],4E35h ; multiply to get next random number mov word [ebx],ax ; stars[cx].addr = ax and ax,0000001100001111b ; mask off unwanted values add al,14 ; make sure al < 30 & al > 14 mov word [ebx+2],ax ; stars[cx].col = ax shr ax,8 ; shift hi byte to low byte inc al ; stars[cx].spd can't be zero mov word [ebx+4],ax ; stars[cx].spd = ax loop loop1 ; do this again for the next star ;[ the main loop, holy shit! ]----------------------------------------------- drawstars: vend: mov dx,03DAh ; vga status port for retrace ;in al,dx ; al = vga status byte (03DAh) ;mov ah,0 ; in (byte) int 34h ; TRDOS 386 - IOCTL interrupt and al,08h ; keep the vretrace status bit jz short vend ; not equal to 1?, check again mov cl,NSTARS ; lets draw NSTARS to the screen loop2: mov bx,cx ; copy cx to bx for indexing again shl bx,3 ; multiply bx by 8 (structure size) add bx,stars ; add start offset of stars to bx mov di,word [ebx] ; di = stars.addr mov [edi],ah ; erase star (ah = 0) add di,word [ebx+4] ; stars.addr = stars.addr + stars.spd mov al,byte [ebx+2] ; al = stars.col mov [edi],al ; draw new star to the screen mov word [ebx],di ; save the updated star posistion loop loop2 ; erase/draw all NSTARS to the screen ;in al,60h ; al = port 60h, keyboard mov dx,60h mov ah,0 ; in (byte) int 34h ; TRDOS 386 - IOCTL interrupt cmp al,1 ; escape key pressed? jnz short drawstars ; was escape pressed, no do it again mov al,03h ; escape was pressed, lets quit ;int 10h ; al = 03h text mode, int 10 video int 31h ; TRDOS 386 - Video interrupt terminate: sys _exit ; INT 40h here: jmp short here stars: ; start of starfield structure