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webserver: attempt to handle circular buffer overflow properly

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This commit is contained in:
Vince Weaver 2016-12-14 16:52:54 -05:00
parent 447cc49f6c
commit ad9db0d0e7
1 changed files with 20 additions and 1 deletions
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21
ethernet/webserver.bas
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@ -113,6 +113,11 @@
930 RA=RM+24576:REM $6000
940 PRINT "READ OFFSET=";RM;" READ ADDRESS=";RA;" READ SIZE=";SI
'
' Check for buffer wraparound
'
942 BW=0
945 IF (SI+TA>=32768) THEN BW=1:BO=32768-TA:PRINT "RX BUFFER WRAPAROUND IN ";BO
'
' Print received packet
'
1000 REM *** PRINT PACKET
@ -124,7 +129,12 @@
1025 IF FL=1 THEN FL$=FL$+C$
1027 IF C=10 THEN FL=0
1030 IF C<>10 THEN PRINT C$;
1032 IF BW=0 THEN GOTO 1040
1033 BO=BO-1: IF BO=0 THEN POKE HA,96:POKE LA,0:BW=0
1040 NEXT I
'
' Deal with first line
'
1050 PRINT "FIRST LINE=";FL$
1060 IF LEFT$(FL$,3)<>"GET" GOTO 7000
1065 N$=""
@ -139,7 +149,7 @@
' TODO: handle wraparound of 8kb buffer
'
'
' TODO: Update read pointer
' Update read pointer
'
1100 REM *** Update read pointer
1110 POKE HA,4: POKE LA,40: REM *** 0x428 Received ptr
@ -191,15 +201,24 @@
1930 TA=TM+16384:REM $4000
1940 PRINT "OH/OL=";OH;"/";OL;" TX OFFSET=";TM;" TX ADDRESS=";TA;" TX SIZE=";SI
'
' Check for buffer wraparound
'
1942 BW=0
1945 IF (SI+TA>=24576) THEN BW=1:BO=24576-TA:PRINT "TX BUFFER WRAPAROUND IN ";BO
'
' Write data to TX buffer
'
2000 T%=TA/256
2005 POKE HA,T%: POKE LA,TA-(T%*256)
2010 FOR I=1 TO LEN(A$)
2015 POKE DP,ASC(MID$(A$,I,1))
2017 IF BW=0 THEN GOTO 2020
2018 BO=BO-1: IF BO=0 THEN POKE HA,96:POKE LA,0:BW=0
2020 NEXT I
2025 FOR I=1 TO FS
2030 POKE DP,PEEK(16383+I)
2032 IF BW=0 THEN GOTO 2035
2033 BO=BO-1: IF BO=0 THEN POKE HA,96:POKE LA,0:BW=0
2035 NEXT I
'
' Update TX write ptr