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#ifndef UDO_TWIST_CHECKPOINTING
#define UDO_TWIST_CHECKPOINTING ##
gitwst_maxundolevels = 32
gitwst_checkpoints[][] init imaxinstances, gitwst_maxundolevels
gitwst_checkpointstate[] init imaxinstances
gitwst_checkpointencodemult = 10000
opcode twst_checkpoint_encode, i, ii
ifnL, ifnR xin
iencoded = (ifnL * gitwst_checkpointencodemult) + (ifnR / gitwst_checkpointencodemult)
xout iencoded
endop
opcode twst_checkpoint_decode, ii, i
iencoded xin
ifnL = int(iencoded) / gitwst_checkpointencodemult
ifnR = frac(iencoded) * gitwst_checkpointencodemult
xout ifnL, ifnR
endop
opcode twst_checkpoint_clear, 0, j
instanceindex xin
instanceindex = (instanceindex == -1) ? gitwst_instanceindex : instanceindex
icheckpointnumber = gitwst_checkpointstate[instanceindex]
while (icheckpointnumber >= 0) do
ifnL, ifnR twst_checkpoint_decode gitwst_checkpoints[instanceindex][icheckpointnumber]
if (ifnL > 0 && ftexists(ifnL) == 1) then
ftfree ifnL, 0
endif
if (ifnR > 0 && ftexists(ifnR) == 1) then
ftfree ifnR, 0
endif
icheckpointnumber -= 1
od
gitwst_checkpointstate[instanceindex] = 0
endop
opcode twst_checkpoint, 0, j
instanceindex xin
imaxundo chnget "twst_maxundo"
imaxundo = (imaxundo == -1) ? gitwst_maxundolevels : imaxundo
if (imaxundo == 0 || imaxundo > gitwst_maxundolevels) then
goto complete
endif
instanceindex = (instanceindex == -1) ? gitwst_instanceindex : instanceindex
icheckpointnumber = gitwst_checkpointstate[instanceindex]
if (icheckpointnumber >= imaxundo) then
ifnL, ifnR twst_checkpoint_decode gitwst_checkpoints[instanceindex][0]
if (ifnL > 0 && ftexists(ifnL) == 1) then
ftfree ifnL, 0
endif
if (ifnR > 0 && ftexists(ifnR) == 1) then
ftfree ifnR, 0
endif
index = 1
itemp[] getrow gitwst_checkpoints, instanceindex
while (index <= imaxundo) do
gitwst_checkpoints[instanceindex][index - 1] = itemp[index]
index += 1
od
gitwst_checkpointstate[instanceindex] = icheckpointnumber ;- 1
else
gitwst_checkpointstate[instanceindex] = icheckpointnumber + 1
endif
ifnL = gitwst_bufferL[instanceindex]
ifnR = gitwst_bufferR[instanceindex]
ilen = ftlen(ifnL)
ifnCheckpointL ftgen 0, 0, ilen, 2, 0
tableicopy ifnCheckpointL, ifnL
if (ifnR > 0) then
ifnCheckpointR ftgen 0, 0, ilen, 2, 0
tableicopy ifnCheckpointR, ifnR
else
ifnCheckpointR = 0
endif
iencoded twst_checkpoint_encode ifnCheckpointL, ifnCheckpointR
gitwst_checkpoints[instanceindex][icheckpointnumber] = iencoded
complete:
endop
opcode twst_undo, i, jp
instanceindex, iapplyundo xin
instanceindex = (instanceindex == -1) ? gitwst_instanceindex : instanceindex
icheckpointnumber = gitwst_checkpointstate[instanceindex]
icheckpointnumber -= 1
if (icheckpointnumber < 0) then
istatus = -1
goto complete
endif
gitwst_checkpointstate[instanceindex] = icheckpointnumber
ifnL, ifnR twst_checkpoint_decode gitwst_checkpoints[instanceindex][icheckpointnumber]
if (iapplyundo == 1) then ; apply or just step back and forget
if (ifnL > 0 && ftexists(ifnL) = 1) then
ftfree gitwst_bufferL[instanceindex], 0
gitwst_bufferL[instanceindex] = ifnL
endif
if (ifnR > 0 && ftexists(ifnR) == 1) then
ftfree gitwst_bufferR[instanceindex], 0
gitwst_bufferR[instanceindex] = ifnR
endif
else
if (ifnL > 0 && ftexists(ifnL) = 1) then
ftfree ifnL, 0
endif
if (ifnL > 0 && ftexists(ifnR) = 1) then
ftfree ifnR, 0
endif
endif
istatus = 1
complete:
xout istatus
endop
#end
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