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decus_20tap1_198111
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decus/20-0002/baildd.fai
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COMMENT VALID 00002 PAGES
C REC PAGE DESCRIPTION
C00001 00001
C00002 00002 title SDDT - makes BAIL your DDT
C00007 ENDMK
C;
title SDDT - makes BAIL your DDT
comment \
.r maklib
*sys:sddt=sys:ddt,dsk:baildd/append:sddt
^ ^ this file
^ block structure ddt
The purpose of this is so that ^C DDT will work in the case
1:DDT;
DDT (POPJ 17,$X to return)
^C
.DDT
\
.load sys:bail
t1__1
t2__2
t3__3
p__17
.jbddt_74
.jbcst_136
external .jbsa,.jbopc,sailor,bail,.uinit,ddbail,.jbrel,.jbhrl,ddt
internal sddt
loc .jbddt ;make this program DDT
,sddt ;our starting address
loc .jbcst ;and put loc of real ddt here for bail
,ddlink
reloc 0
sddt: movem t1,savacs
movei t1,ddbail ;in future use bail, not us
setddt t1,
jfcl
skipe sailor ;if sailor is set, program has started
jrst break ;do regular bail break processing
movem t2,savacs+1 ;otherwise break coord 0 and start
movem t3,savacs+2
movei t3,0 ;code for setting hi seg write priv
hrrz t1,.jbsa ;start searching for coordinate 0
trnn t1,400000 ;if in hi segment
jrst nothi
setuwp t3, ; then set hi seg write priv
jrst go ; if we can't, forget all this
movem t3,olduwp ;save for later since we need t3
nothi: hrrz t3,.jbrel ;upper limit for seaach - highest legal addr
trne t1,400000 ;unless we are in high seg
hrrz t3,.jbhrl ;then use high seg limit
next: move t2,(t1) ;look at program
camn t2,[pushj p,.uinit] ;find coordinate 0
jrst found
camge t1,t3 ;reached upper limit?
aoja t1,next ;no - go on
jrst go ;can't find it, so forget all this
found: move t2,[pushj p,bailst] ;replace coord 0 with a break
movem t2,(t1)
move t3,olduwp ;get back old high-seg protection
trne t1,400000 ;if in high segment
setuwp t3, ;set hi seg write prot back the way it was
jfcl
go: move t3,savacs+2
move t2,savacs+1
hrrz t1,.jbsa ;have to strip off LH(.JBSA) for indirect jrst
exch t1,savacs
jrst @savacs ;now start main program
bailst: pushj p,.uinit ;here at initial break - do what was there
move t1,[pushj p,.uinit] ;then remove the break
move t2,(p) ;this is return addr = addr of break+1
movei t3,0 ;clear hi seg prot if needed
trnn t2,400000 ;see if hi segment
jrst nothigh
setuwp t3, ;now clear protection
jrst bail ;can't, forget all this
nothigh: movem t1,-1(t2) ;restore the broken location
trne t2,400000 ;and restore hi seg write protection
setuwp t3,
jfcl
jrst bail ;now make bail think it was called
;from coordinate 0
break: movei t1,savacs ;here if program already started
jrst ddbail ;and let bail handle it
ddlink: movem t1,savacs ;here if bail trying to call ddt
movei t1,ddt ;set so ddt command is in right context
setddt t1,
jfcl
move t1,savacs
pushj p,ddt ;now it is safe to goto ddt
movem t1,savacs ;here on return from ddt
movei t1,ddbail ;reset to sail context
setddt t1,
jfcl
move t1,savacs
popj p, ;return to bail
savacs: block 3
olduwp: block 1
end