A83: Link Routines

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A83: Link Routines


Hi,

If anyone could be so kind to try to resolve this problem:
I'm just on the point of finishing a link game, the link routines work well
when tested but the game blocks from time to time, I use a TI-83 and a TI-83
Plus, the TI-83's link port is a bit used. I cannot figure out if it's my
routines, the TI-83 or the constants I use. Anyway, here's my source:

The sensible constant is TimeOut, under 1000h, any higher they block, time
depending on their value, i.e. half a second for 1000h and 2 secs for 5000h
bTransMask is equated to D0LD1H ^ (XOR) D0HD1L

; -------------------------
; | Begin | Link Routines |
CheckByte:
 LD A, D0HD1H
 OUT (LinkPort), A

 IN A, (LinkPort)
 AND LinkMask
 CP LinkMask
 SCF
 RET Z

RecieveByte:
 PUSH BC
 LD B, 08h

RecieveBits:
 LD DE, TimeOut

WaitBitRec:
; Recieve Bit 0: 01
; Recieve Bit 1: 10
 CALL ScanLink
 JR Z, LinkError
 CP LinkMask
 JR Z, WaitBitRec

 CP bLink1
#IfNDef Plus
 JR NC, RecHigh

RecLow:
 LD A, D0LD1H
 JR CommonLinkCode

RecHigh:
 LD A, D0HD1L
#EndIf

CommonLinkCode:
 RR C
 OUT (LinkPort), A
 XOR bMaskTrans
#IfNDef Plus
 AND LinkMask >> 2
 RLA
 RLA
#Else
 AND LinkMask
#EndIf
 LD (AckWait), A
WaitNotZero:
 CALL ScanLink
AckWait  EQU $ + 01h
 SUB NULL
 JR NZ, WaitNotZero

ResetLink:
#IfNDef Plus
 LD A, D0HD1H
#EndIf
 OUT (LinkPort), A

 LD D, 04h
WaitReady:
 DEC D
 JR Z, LinkReady
 IN A, (LinkPort)
 AND LinkMask
 CP LinkMask
 JR NZ, WaitReady

LinkReady:
 DJNZ RecieveBits
 OR A
 LD A, C
 POP BC
 RET


ScanLink:
 POP HL
 DEC DE
 LD A, D
 OR E
 JR Z, LinkError
 BIT OnInterrupt, (IY + OnFlags)
 JR NZ, LinkError
 IN A, (LinkPort)
 AND LinkMask
 JP (HL)

LinkError:
 POP BC
 SCF
 RET


SendByte:
 PUSH BC
 LD C, A
 LD B, 09h
 JR SendRes

SendBits:
 LD A, D0HD1L
 RR C
 JR C, SendHigh

SendLow:
 LD A, D0LD1H

SendHigh:
 OUT (LinkPort), A

 LD DE, TimeOut
WaitSndCls:
 CALL ScanLink
 JR NZ, WaitSndCls

SendRes:
 LD A, D0HD1H
 OUT (LinkPort), A
 LD DE, TimeOut
WaitSndReady:
 CALL ScanLink
 CP LinkMask
 JR NZ, WaitSndReady
 DJNZ SendBits
 POP BC
 OR A
 RET
; | End | Link Routines |
; -----------------------



Solignac Julien
Alias x1Cygnus
x1cygnus@online.fr
http://x1cygnus.online.fr/