www.pudn.com > zsnes117b-src.zip > sw32.asm
;Copyright (C) 1997-2001 ZSNES Team ( zsknight@zsnes.com / _demo_@zsnes.com )
;
;This program is free software; you can redistribute it and/or
;modify it under the terms of the GNU General Public License
;as published by the Free Software Foundation; either
;version 2 of the License, or (at your option) any later
;version.
;
;This program is distributed in the hope that it will be useful,
;but WITHOUT ANY WARRANTY; without even the implied warranty of
;MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;GNU General Public License for more details.
;
;You should have received a copy of the GNU General Public License
;along with this program; if not, write to the Free Software
;Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
;32-bit DOS-Mode driver for the Microsoft Sidewinder Gamepad
;Multi-SW Version 1.5
;(C) 1997, 1998 Robert William Grubbs, All Rights Reserved
;Latest revision 1/20/98
; Driver Source code Include file
;C-linkable, rewrote decoder -sardu
;Flat memory mode (Protected mode extender required! Tested with DOS32)
;Tested with TASM 4.0+
SW1 dd 0 ;SW #1's button status
SW2 dd 0 ;SW #2's button status
SW3 dd 0 ;SW #3's button status
SW4 dd 0 ;SW #4's button status
SWCount dd 1 ;Tell the driver how many sidewinders are present
SWSetup dd 0 ;Tell the driver what polling mode to use
; 0=Interrupts disabled, Multiple OUT statements
; 1=Interrupts disabled, Single OUT statement
; 2=Interrupts enabled, Multiple OUT statements
; 3=Interrupts enabled, Single OUT statement
gDump times 100h db 0 ;SW Status dump buffer (space for 256 bytes, uses 200)
bDump times 80h db 0 ;buffer to hold button data (Modes A and B, all SW)
;This macro calculates parity for the buttons and compares it to the SW's
; parity bit. If they don't match, the button data is discarded.
%macro ParityCheckSW 1
mov ecx,ebx ;duplicate button status
xor cl,ch ;
jpe %%ParChkSW
mov [%1],ebx ;update button status for SW #n
%%ParChkSW ;done
%endmacro
;The main subroutine; this is the important one; bow down before it
;IN: None
;Out: SWx=buttons (bit 0=null 1=up 2=dn 3=rt 4=lt 5=A 6=B 7=C 8=X)
; (9=Y 10=Z 11=L 12=R 13=St 14=M 15=Parity)
;No registers destroyed
readSideWinder:
pushad
mov ecx,200 ;dump buffer fill size
mov ebx,gDump ;initial dump pointer
mov edx,0201h ;joystick port
cmp dword[SWSetup],0
jne NotSW0
cli ;Disable interrupts (required to avoid jitter)
GetSWDataLoop: ;
out dx,al ;trigger joystick port
in al,dx ;read SW status byte
mov [ebx],al ;dump status byte
inc ebx ;increment dump pointer
dec ecx
jnz GetSWDataLoop
sti ;Re-enable interrupts
jmp SWPollDone
NotSW0:
cmp dword[SWSetup],1
jne NotSW1
cli ;Disable interrupts (required to avoid jitter)
out dx,al ;trigger joystick port
GetSWDataLoop1: ;
in al,dx ;read SW status byte
mov [ebx],al ;dump status byte
inc ebx ;increment dump pointer
dec ecx
jnz GetSWDataLoop1
sti ;Re-enable interrupts
jmp SWPollDone
NotSW1:
cmp dword[SWSetup],2
jne NotSW2
GetSWDataLoop2: ;
out dx,al ;trigger joystick port
in al,dx ;read SW status byte
mov [ebx],al ;dump status byte
inc ebx ;increment dump pointer
dec ecx
jnz GetSWDataLoop2
jmp SWPollDone
NotSW2:
;default all others to SWStatus=3
out dx,al ;trigger joystick port
GetSWDataLoop3: ;
in al,dx ;read SW status byte
mov [ebx],al ;dump status byte
inc ebx ;increment dump pointer
dec ecx
jnz GetSWDataLoop3
SWPollDone:
mov ecx,0 ;tick count
mov esi,1 ;initialize output mask
mov ebx,0 ;initialize output
mov edi,0 ;initialize input pointer
;My current method of cycle detection is to look for 15 highs in a row on
; the strobe line. Cycle ends is detected by 15 lows in a row.
;Mode A has 15 strobes in a cycle, Mode B has 5.
; Note that the 15 highs/lows for cycle detection may be too high for slow
; machines. I havn't seen a problem yet, but it may exist...
;Multiple Sidewinder data complicates things. Each additional SW tags
; another set of strobes to the cycle, 5 more in mode B, 15 more in mode A.
; Detecting extra SW gamepad data is fairly simple: count the number of
; strobes. If it is a multiple of 5, you're in mode B and can divide by 5
; to get the total number of gamepads. If it's divisible by 15, use mode A.
; However, this method cannot distinguish between mode A for one SW and mode
; B for three SW. In that case, the SWCount variable must be set correctly.
FindCycle:
mov al,[gDump+edi] ;get next status byte
inc edi ;increment input pointer
cmp edi,200 ;test for end of status block
je SWNoFind ;if it's the end, quit sub with error
test al,00010000b ;Check for nonzero bits
jnz WMFCS1 ;
xor ecx,ecx ;if zero, reset tick count
jmp FindCycle ;can't be pre-cycle
WMFCS1: ;Possibly pre-cycle
inc ecx ;increment tick count
cmp ecx,15 ;test for sufficient ticks for cycle start
jne FindCycle ;if insufficient, get next status byte
;Yippie! it found a (probable) cycle!
mov ebp,0 ;initialize bDump index (strobe count)
FindStrobeLow: ;Search for leading edge of data strobe
mov al,[gDump+edi] ;get next status byte
inc edi ;increment input pointer
cmp edi,200 ;test for end of status block
je SWNoFind ;if it's the end, quit sub with error
test al,00010000b ;get "strobe" bit
jnz SHORT FindStrobeLow ;if it isn't zero, we're not there yet
xor ecx,ecx ;initialize cycle end test count
FindStrobeHigh:
inc ecx ;increment zero count
cmp ecx,0fh ;is it 15?
je SWModeCheck ;if so, goto mode check
mov al,[gDump+edi] ;get next status byte
inc edi ;increment input pointer
cmp edi,200 ;test for end of status block
je SWNoFind ;if it's the end, quit sub with error
test al,00010000b ;get "strobe" bit
jz FindStrobeHigh ;if it is zero, we're not there yet
;if not, we're there! data bit is valid (probably)
mov [bDump+ebp],al ;preserve data for button decoding
inc ebp ;increment strobe count/bDump index
jmp FindStrobeLow ;wait for the next button
SMWDone:
SWNoFind:
popad
ret ;return to calling procedure
SWModeCheck: ;Check strobe count to identify mode and # of SW
cmp ebp,15 ;Is it Mode A with 1 Sidewinder or B with 3?
je ModeA1
cmp ebp,5 ;Is it Mode B with 1 Sidewinders?
je ModeB1
cmp ebp,30 ;Is it Mode A with 2 Sidewinders?
je ModeA2
cmp ebp,10 ;Is it Mode B with 2 Sidewinders?
je near ModeB2
cmp ebp,45 ;Is it Mode A with 3 Sidewinders?
je near ModeA3
cmp ebp,60 ;Is it Mode A with 4 Sidewinders?
je near ModeA4
cmp ebp,20 ;Is it Mode B with 4 Sidewinders?
je near ModeB4
jmp SHORT SWNoFind ;Any other # of strobes is invalid data
ModeB1:
xor ebp,ebp
call DoModeB
ParityCheckSW SW1
jmp SMWDone
ModeA1:
cmp dword [SWCount],3
je near ModeB3
xor ebp,ebp
call DoModeA
ParityCheckSW SW1
jmp SMWDone
ModeA2:
xor ebp,ebp
call DoModeA
ParityCheckSW SW1
mov ebp,15
call DoModeA
ParityCheckSW SW2
jmp SMWDone
ModeA3:
xor ebp,ebp
call DoModeA
ParityCheckSW SW1
mov ebp,15
call DoModeA
ParityCheckSW SW2
mov ebp,30
call DoModeA
ParityCheckSW SW3
jmp SMWDone
ModeA4:
xor ebp,ebp
call DoModeA
ParityCheckSW SW1
mov ebp,15
call DoModeA
ParityCheckSW SW2
mov ebp,30
call DoModeA
ParityCheckSW SW3
mov ebp,45
call DoModeA
ParityCheckSW SW4
jmp SMWDone
ModeB2:
xor ebp,ebp
call DoModeB
ParityCheckSW SW1
mov ebp,5
call DoModeB
ParityCheckSW SW2
jmp SMWDone
ModeB3:
xor ebp,ebp
call DoModeB
ParityCheckSW SW1
mov ebp,5
call DoModeB
ParityCheckSW SW2
mov ebp,10
call DoModeB
ParityCheckSW SW3
jmp SMWDone
ModeB4:
xor ebp,ebp
call DoModeB
ParityCheckSW SW1
mov ebp,5
call DoModeB
ParityCheckSW SW2
mov ebp,10
call DoModeB
ParityCheckSW SW3
mov ebp,15
call DoModeB
ParityCheckSW SW4
jmp SMWDone
ENDP
%macro SWRepeat 1
mov al,[bDump+ebp+%1]
shr al,5 ;get upper 3 bits
shl eax,1+3*%1 ;shift into place
or ebx,eax ;or into output
%endmacro
DoModeB:
xor ebx,ebx ;Initialize output
xor eax,eax
SWRepeat 0
SWRepeat 1
SWRepeat 2
SWRepeat 3
SWRepeat 4
xor ebx,0FFFEh
ret
DoModeA:
xor ebx,ebx ;Clear output
mov ecx,15 ;bit count
ALP:
mov al,[bDump+ebp]
inc ebp
shl al,3
rcr ebx,1
dec ecx
jg ALP
shr ebx,16
xor ebx,0FFFEh
ret