]

x86 Assembly implementation of xorshift (8\16\32)

;Xorshift32:
;state ^= state << 13
;state ^= state >> 17
;state ^= state << 5

xorshift32:
  push eax
  mov eax, [state32]
	shl eax, 13
	xor [state32], eax
	mov eax, [state32]
	shr eax, 17
	xor [state32], eax
	mov eax, [state32]
	shl eax, 5
	xor [state32], eax
	pop eax
	ret
  
;Xorshift16:
;state ^= state << 7
;state ^= state >> 9
;state ^= state << 8

xorshift16:
	push ax
	mov ax, [state16]
	shl ax, 7
	xor [state16], ax
	mov ax, [state16]
	shr ax, 9
	xor [state16], ax
	mov ax, [state16]
	shl ax, 8
	xor [state16], ax
	pop ax
	ret
  
;Xorshift8:
;state ^= state << 1
;state ^= state >> 1
;state ^= state << 2

xorshift8:
  push ax
  mov al, [state8]
  shl al, 1
  xor [state8], al
  mov al, [state8]
  shr al, 1
  xor [state8], al
  mov al, [state8]
  shl al, 2
  xor [state8], al
  pop ax
  ret
  
;bonus (realmode only!)
;seeds prng(s) using int 1Ah AH = 0
;basically like GetTickCount from WinAPI but for realmode
seedrng:
  pushad
  xor ax, ax
  int 1Ah
  mov [state8], dl
  mov [state16], dx
  shl ecx, 16
  mov cx, dx
  mov [state32], ecx
  popad
  ret
  
state8 db 0
state16 dw 0
state32 dd 0