www.pudn.com > zsnes117b-src.zip > gppro.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. 
 
%include "macros.mac" 
 
section .data 
sample times 60 db 0 
clock_mask db 0 
data_mask db 0 
 
section .text 
 
NEWSYM read_gpp 
   push ebx 
   push ecx 
   push edx 
   push edi 
   push esi 
 
   cmp al,0 
   jne GPP_L14 
   mov byte [clock_mask],0x10 
   mov byte [data_mask],0x20 
   jmp GPP_L15 
GPP_L14: 
   mov byte [clock_mask],0x40 
   mov byte [data_mask],0x80 
GPP_L15: 
 
 
   xor ebx,ebx 
   xor edi,edi 
 
   cli 
   in al,dx 
   mov ah,al 
 
GPP_L4: 
   xor ecx,ecx 
GPP_L0: 
   nop 
   nop 
   nop 
   nop 
   nop 
   nop 
   in al,dx 
   cmp al,ah 
   jne GPP_L1 
   inc ecx 
   cmp ecx,255 
   jl GPP_L0 
GPP_L1: 
   cmp ecx,255 
   je near GPP_ERR 
 
   test [clock_mask],ah 
   jz GPP_L2 
   test [clock_mask],al 
   jnz GPP_L2 
 
   test [data_mask],al 
   jz GPP_L3 
   mov byte [sample+edi],1 
   jmp GPP_L12 
GPP_L3: 
   mov byte [sample+edi],0 
GPP_L12: 
   inc edi 
 
GPP_L2: 
   mov ah,al 
   cmp ebx,200 
   je GPP_L13 
   inc ebx 
   cmp edi,50 
   jl GPP_L4 
 
GPP_L13: 
   sti 
   xor ecx,ecx 
   mov esi,1 
GPP_L7: 
   cmp byte [sample+esi],1 
   jg GPP_ERR 
   jne GPP_L6 
   inc ecx 
   jmp GPP_L5 
GPP_L6: 
   xor ecx,ecx 
 
GPP_L5: 
   cmp ecx,5 
   je GPP_L8 
   cmp esi,edi 
   je GPP_L8 
   inc esi 
   jmp GPP_L7 
 
GPP_L8: 
   cmp ecx,5 
   jne GPP_ERR 
   add esi,2 
   xor eax,eax 
   xor ebx,ebx 
   xor ecx,ecx 
   xor edx,edx 
 
GPP_L10: 
   inc ecx 
   cmp ecx,5 
   jne GPP_L11 
   mov ecx,1 
   inc esi 
GPP_L11: 
   mov dl,[sample+esi] 
   or eax,edx 
   shl eax,1 
   cmp ebx,13 
   je GPP_L9 
   inc ebx 
   inc esi 
   jmp GPP_L10 
 
GPP_L9: 
   pop esi 
   pop edi 
   pop edx 
   pop ecx 
   pop ebx 
   ret 
 
GPP_ERR: 
   sti 
   pop esi 
   pop edi 
   pop edx 
   pop ecx 
   pop ebx 
   mov eax,1 
   ret