pouët.net

; shapes in a plane
; by fizzer

;cpu 486
org 0x100
bits 16

mov al, 0x13
int 0x10

push word 0xa000
pop es
push word 0x0040
pop fs




mainloop:
  dec cx

  xor di, di
	
	mov ax, word [fs:0x6C]
	shr ax, 7
	and ax, 6
	add ax, 4
	mov word [sides], ax
	
  pixelloop:
    push cx
    push di

    mov ax, 0xCCCD
    mul di

    xor ax, ax
    mov al, dl
    mov word [dirx], ax

    mov al, dh
    mov word [diry], ax
	
	mov dl, 70
	mov si, 65535
	mov bx, word [speed2]
	
	call shape
	
    add word [dirx], bx
	call shape
	
    add word [diry], bx
	call shape
	
    sub word [dirx], bx
	call shape
	
	and dx, si
	mov ax, dx
	
    pop di
    stosb

    pop cx
    dec cx
  jnz pixelloop

in al, 60h
cmp al, 1
jnz mainloop


myfunc:
	fxch st2
	fidiv word [speed]
	fld st0
	frndint
	fsubp
	fmulp
	ret

shape:
	fldz
	fst dword [dist]
	mov cx, word [sides]
poly:
	fild word [diry]
	fild word [dirx]
	fild word [fs:0x6C]
	faddp
	fld st2
	fsincos
	
	call myfunc
	call myfunc

	
	faddp
	fld dword [dist]

	fcomi
	fcmovb st0, st1
	fstp dword [dist]
	fstp st0
	fld dword [twopi]
	fidiv word [sides]
	faddp
	loop poly


	fld dword [dist]
	fld dword [thresh]

	fild word [fs:0x6C]
	fidiv word [speed]
	fsin
	fmul dword [thresh]
	fmul dword [thresh]
	faddp
	
	fcomi
	jb notgreater2
	add dx, 3
notgreater2:

	fsubp
	fabs
	fld1
	fidiv word [speed]
	fcomip
	jb notgreater3
	xor si, si
notgreater3:
	fstp st0

	ret
	
	

section .data

speed dw 100
speed2 dw 50
thresh dd 0.3
twopi dd 6.283185307179586

section .bss

dirx resw 1
diry resw 1
dist resd 1
sides resw 1