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  1. Path: abcfd20.larc.nasa.gov!amiga-request
  2. From: amiga-request@abcfd20.larc.nasa.gov (Amiga Sources/Binaries Moderator)
  3. Subject: v90i278: GDosTool - test/set memory location 0, Part01/01
  4. Reply-To: "John Davis,chem dept, UoC NZ" <CHEM194@canterbury.ac.nz>
  5. Newsgroups: comp.sources.amiga
  6. Message-ID: <comp.sources.amiga:v90i278@abcfd20.larc.nasa.gov>
  7. Date: 14 Oct 90 18:19:25 GMT
  8. Approved: tadguy@uunet.UU.NET (Tad Guy)
  9. X-Mail-Submissions-To: amiga@uunet.uu.net
  10. X-Post-Discussions-To: comp.sys.amiga
  11.  
  12. Submitted-by: "John Davis,chem dept, UoC NZ" <CHEM194@canterbury.ac.nz>
  13. Posting-number: Volume 90, Issue 278
  14. Archive-name: util/gdostool/part01
  15.  
  16. [ uuencoded executable and icons enclosed  ...tad ]
  17.  
  18. A tiny utility that will tell you (via a requester) whether memory
  19. location 0 is set to a non-zero value, and give you an option to
  20. either clear it, or set it to a 'problem' value. The first option
  21. is handy for people with 2091s and A590s, which have been known
  22. to set $0="GDOS", the facility to set $0='GDOS' is handy for 
  23. software authors wishing to make sure their programs aren't
  24. accidentally (either thru nil pointers or dropped #'s in assembler)
  25. using $0 as a pointer.
  26.  
  27. #!/bin/sh
  28. # This is a shell archive.  Remove anything before this line, then unpack
  29. # it by saving it into a file and typing "sh file".  To overwrite existing
  30. # files, type "sh file -c".  You can also feed this as standard input via
  31. # unshar, or by typing "sh <file", e.g..  If this archive is complete, you
  32. # will see the following message at the end:
  33. #        "End of archive 1 (of 1)."
  34. # Contents:  gdostool.doc gdostool.s gdostool.s.uu gdostool.uu
  35. #   gdostool0.uu gdostool1.uu
  36. # Wrapped by tadguy@abcfd20 on Sun Oct 14 14:19:23 1990
  37. PATH=/bin:/usr/bin:/usr/ucb ; export PATH
  38. if test -f 'gdostool.doc' -a "${1}" != "-c" ; then 
  39.   echo shar: Will not clobber existing file \"'gdostool.doc'\"
  40. else
  41. echo shar: Extracting \"'gdostool.doc'\" \(1285 characters\)
  42. sed "s/^X//" >'gdostool.doc' <<'END_OF_FILE'
  43. XGdosTool - By J Davis 08/1990
  44. X
  45. XWhy
  46. X---
  47. X
  48. XAn  easy  mistake  to make when progrmming in assembler is to accidentally
  49. Xuse  $0 (the value in memory location $0) where you mean #$0 (the constant
  50. Xvalue  zero).   A  subtle  mistake - one not aided by the fact that memory
  51. Xloaction  0  often holds 0, so it will yield the right results.  
  52. X
  53. XThe first you notice of this problem is when your code is run on some a590
  54. Xequipped  500's  ,  or  2000s with 2091 controllers, where $0 may actually
  55. Xhold  the  string  'GDOS'.  The same situation can also occur in most high
  56. Xlevel languages, by de-referencing a NIL pointer.
  57. X
  58. XThe  result  can  be anything from small errors upto a full blown GURU (if
  59. Xthe  code  tries  to  de-ref  $0  as a pointer to a word - it will yield a
  60. Xnon-word aligned word access)
  61. X 
  62. XThis is a common problem (other programs that have trouble with a non zero
  63. Xlocation  0  are  virusx4,  lharc1.20,  execellence  1.11,  Jrcomm 1.0 and
  64. Xseveral others).
  65. X 
  66. XBy  using  this tool you can set location zero to a 'problem' value before
  67. Xtesting  your code - this will hopefully make the release of programs with
  68. Xsuch 'mistakes' less common.
  69. X 
  70. XYou  can  also  set  it  back  to  $0000000 - useful after you've finished
  71. Xtesting, and also potentially useful for people with a590s or 2091s.
  72. X
  73. END_OF_FILE
  74. if test 1285 -ne `wc -c <'gdostool.doc'`; then
  75.     echo shar: \"'gdostool.doc'\" unpacked with wrong size!
  76. fi
  77. # end of 'gdostool.doc'
  78. fi
  79. if test -f 'gdostool.s' -a "${1}" != "-c" ; then 
  80.   echo shar: Will not clobber existing file \"'gdostool.s'\"
  81. else
  82. echo shar: Extracting \"'gdostool.s'\" \(3694 characters\)
  83. sed "s/^X//" >'gdostool.s' <<'END_OF_FILE'
  84. X; program to allow user examination and setting of ($0)
  85. X; 
  86. X; allows both simulation of the $0='GDOS' phenomena on some a590s and
  87. X; 2091s ( useful for testing code for nil pointer de-references and
  88. X; incorrect use of $0 when it should be #$0
  89. X;
  90. X; also allows clearing of $0, either to remove settings from previous
  91. X; use, or due to the a590/2091 itself
  92. X
  93. Xforbid        equ    -$084    ; offsets for various exec and int calls
  94. Xgetmsg        equ    -$174    ; saves long includes and compile times
  95. Xreplymsg    equ    -$17a
  96. Xwaitport    equ    -$180
  97. Xfindtask    equ    -$126
  98. Xautoreq        equ    -$15c
  99. Xopenlib        equ    -$228
  100. Xcloselib    equ    -$19e
  101. X
  102. Xpr_cli        equ    $0Ac    ; process cli flag offset
  103. Xpr_msgport    equ    $05c    ; process msgport offset
  104. X
  105. Xstartup:    move.l    $4,a6
  106. X        move.l    #0,a1
  107. X        jsr    findtask(a6)        ; find ourselves
  108. X
  109. X        move.l    d0,a4            ; save our process pointer
  110. X
  111. X        move.l    pr_cli(a4),d0
  112. X        bne    fromdos            ; was a DOS startup
  113. X
  114. X        ; was started from WB
  115. X
  116. X        lea    pr_msgport(a4),a0
  117. X        jsr    waitport(a6)        ; wait for startup msg
  118. X        lea    pr_msgport(a4),a0
  119. X        jsr    getmsg(a6)        ; get the wb msg
  120. X
  121. X        move.l    d0,wbmsg        ; save pointer to our startup msg
  122. X        move.l    #1,wb            ; flag we started from wb
  123. X
  124. Xfromdos:    move.l    $0,d0
  125. X        cmp.l    #$0,d0
  126. X        beq    is_zero            ; if $0=0 then req already setup
  127. X
  128. X        lea    nzbodytext,a0
  129. X        move.l    a0,ctext        ; set so req displays non-zero msg
  130. X        bra    _xx
  131. X
  132. Xis_zero:    lea    zbodytext,a0
  133. X        move.l    a0,ctext
  134. X
  135. X_xx:        lea    intuiname,a1
  136. X        move.l    #0,d0
  137. X        move.l    $4,a6
  138. X        jsr    openlib(a6)         ; open intuition lib
  139. X
  140. X        move.l    d0,a6            ; save ibase
  141. X        
  142. X        move.l    #0,a0            ; window to display in
  143. X        move.l    #bodyitext,a1        ; body text
  144. X        move.l    #yesitext,a2         ; postive text
  145. X        move.l    #noitext,a3          ; negative text
  146. X        move.l    #0,d0            ; pflags
  147. X        move.l    #0,d1            ; nflags
  148. X        move.l    #640,d2            ; width
  149. X        move.l    #50,d3            ; height
  150. X        jsr    autoreq(a6)        ; request user confirmation
  151. X
  152. X        cmp.l    #0,d0
  153. X        beq    cleargdos        ; user selected clear
  154. X
  155. Xsetgdos:    move.l    #"GDOS",$0        ; set $0="GDOS"        
  156. X        bra    _n1
  157. X
  158. Xcleargdos:    move.l    #$0,$0
  159. X
  160. X_n1:        move.l    a6,a1            ; close intuition lib
  161. X        move.l    $4,a6
  162. X        jsr    closelib(A6)
  163. X        
  164. Xexit:        move.l    wb,d0
  165. X        cmp.l    #$0,d0            ; was this a CLI invocation
  166. X        beq    exit_dos
  167. X
  168. X        ; workbench exit
  169. X
  170. X        move.l    $4,a6
  171. X        jsr    forbid(a6)        ; lock out everyone else
  172. X
  173. X        move.l    wbmsg,a1
  174. X        jsr    replymsg(a6)        ; reply to Wbstartup msg
  175. X
  176. Xexit_dos:    move.l    #0,d0            ; return with return code 0
  177. X        rts            
  178. X
  179. X;=============================================================
  180. X        
  181. Xwb:        dc.l    0            ; run mode flag 0=dos process 1=wbprocess
  182. Xwbmsg:        dc.l    0            ; where we save our workbench msg
  183. X
  184. Xintuiname:    dc.b    "intuition.library",0
  185. X
  186. X; stuff for our autorequester
  187. X
  188. Xbodyitext:    dc.b    0           ; front pen
  189. X        dc.b    1           ; back pen
  190. X        dc.b    0           ; draw mode
  191. X        dc.w    0           ; leftedge
  192. X        dc.w    6           ; topedge
  193. X        dc.l    0           ; textattr = default
  194. X        dc.l    bodytext1      ; actual text
  195. X        dc.l    nbodyitext     ; next
  196. X
  197. Xnbodyitext:    dc.b    0           ; front pen
  198. X        dc.b    1           ; back pen
  199. X        dc.b    0           ; draw mode
  200. X        dc.w    0           ; leftedge
  201. X        dc.w    20           ; topedge
  202. X        dc.l    0           ; textattr = default
  203. Xctext:        dc.l    0          ; actual text
  204. X        dc.l    0         ; next
  205. X
  206. X
  207. Xyesitext:    dc.b    2        ; front pen
  208. X        dc.b    1        ; back pen
  209. X        dc.b    0        ; draw mode
  210. X        dc.w    4        ; leftedge
  211. X        dc.w    4        ; topedge
  212. X        dc.l    0        ; textattr = default
  213. X        dc.l    yestext        ; actual text
  214. X        dc.l    0        ; next
  215. X        
  216. Xnoitext:    dc.b    2        ; front pen
  217. X        dc.b    1        ; back pen
  218. X        dc.b    0        ; draw mode
  219. X        dc.w    4        ; leftedge
  220. X        dc.w    4        ; topedge
  221. X        dc.l    0        ; textattr = default
  222. X        dc.l    notext        ; actual text
  223. X        dc.l    0        ; next        
  224. X
  225. X        ; actual text for our requester
  226. X
  227. Xbodytext1:    dc.b    "   SetGDOS by J Davis, 08-1990 v1.0 - an aid to hunting nil pointer de-refs",0
  228. Xzbodytext:    dc.b    "                  Location $0 currently holds a NULL (0) value",0
  229. Xnzbodytext:    dc.b    "                     Location $0 is currently NON-ZERO",0
  230. X
  231. Xyestext:    dc.b    "Set $0='GDOS'",0
  232. Xnotext:        dc.b    "Set $0=NULL",0
  233. X
  234. X        END
  235. END_OF_FILE
  236. if test 3694 -ne `wc -c <'gdostool.s'`; then
  237.     echo shar: \"'gdostool.s'\" unpacked with wrong size!
  238. fi
  239. # end of 'gdostool.s'
  240. fi
  241. if test -f 'gdostool.s.uu' -a "${1}" != "-c" ; then 
  242.   echo shar: Will not clobber existing file \"'gdostool.s.uu'\"
  243. else
  244. echo shar: Extracting \"'gdostool.s.uu'\" \(538 characters\)
  245. sed "s/^X//" >'gdostool.s.uu' <<'END_OF_FILE'
  246. Xbegin 666 gdostool.s.info
  247. XMXQ```0```````````"``'``%``,``0#%\-@`````````````````````````&
  248. XM````!```QA]Z`,7OXH````"````````````````````````````@`!P``@#%\
  249. XM[_@#````````````!___^`?___@&$)(8!S.3.`<PQS@',Y,X!S"3.`?___@$G
  250. XM```(!___^`?_?[@'_O-X!_S-.`?Z,M@'_W^X!][S>`<DS3@/FC+8#WO]^`[WY
  251. XMF_@9)FGX'-&6^#____A____X#___^````````````````````````````>]MZ
  252. XMY@#,;,8`SSC&`,QLQ@#/;,8````&`___]@````8``(!&``$,A@`#,L8`!<TF_
  253. XM``"`1@`A#(8`VS+&`&7-+@"$`@X!"&0.!MF6'@,N:1X````^````_@____X#0
  254. XG___^``````````9C.F-E9``````(````#D9)3$5465!%/51E>'0`E
  255. X``
  256. Xend
  257. Xsize 354
  258. END_OF_FILE
  259. if test 538 -ne `wc -c <'gdostool.s.uu'`; then
  260.     echo shar: \"'gdostool.s.uu'\" unpacked with wrong size!
  261. fi
  262. # end of 'gdostool.s.uu'
  263. fi
  264. if test -f 'gdostool.uu' -a "${1}" != "-c" ; then 
  265.   echo shar: Will not clobber existing file \"'gdostool.uu'\"
  266. else
  267. echo shar: Extracting \"'gdostool.uu'\" \(1559 characters\)
  268. sed "s/^X//" >'gdostool.uu' <<'END_OF_FILE'
  269. Xbegin 666 gdostool
  270. XM```#\P`````````!``````````````"5```#Z0```)4L>0````0B?`````!.B
  271. XMKO[:*$`@+`"L9@``(D'L`%Q.KOZ`0>P`7$ZN_HPCP````1`C_`````$```$,A
  272. XM(#D`````L+P`````9P``$D'Y```"`2/(```!1F````Y!^0```<(CR````49#-
  273. XM^0```10@/``````L>0````1.KOW8+$`@?``````B?````28D?````4XF?```"
  274. XM`6(@/``````B/``````D/````H`F/````#).KOZDL+P`````9P``$"/\1T1/-
  275. XM4P````!@```,(_P``````````").+'D````$3J[^8B`Y```!#+"\`````&<`,
  276. XM`!8L>0````1.KO]\(GD```$03J[^AB`\`````$YU``````````!I;G1U:71I'
  277. XM;VXN;&EB<F%R>0```0``````!@````````%V```!.@`!```````4````````.
  278. XM`````````@$````$``0````````".``````"`0````0`!`````````)&````8
  279. XM`"`@(%-E=$=$3U,@8GD@2B!$879I<RP@,#@M,3DY,"!V,2XP("T@86X@86ED8
  280. XM('1O(&AU;G1I;F<@;FEL('!O:6YT97(@9&4M<F5F<P`@("`@("`@("`@("`@*
  281. XM("`@("!,;V-A=&EO;B`D,"!C=7)R96YT;'D@:&]L9',@82!.54Q,("@P*2!VB
  282. XM86QU90`@("`@("`@("`@("`@("`@("`@("!,;V-A=&EO;B`D,"!I<R!C=7)R,
  283. XM96YT;'D@3D].+5I%4D\`4V5T("0P/2='1$]3)P!3970@)#`]3E5,3```````4
  284. XM`^P````0`````````"P````V````3````%(```!<````8@```&@```"&````K
  285. XMC````)(```#B````_````3(```$V```!6@```6X````````#\`````%W8@``]
  286. XM```!#`````%?;C$`````U`````%?>'@`````9@````%E>&ET````X`````)C6
  287. XM=&5X=````````48````"=V)M<V<```````$0`````FYO=&5X=``````"1@``K
  288. XM``)F<F]M9&]S`````#H````":7-?>F5R;P````!:`````FYO:71E>'0````!;
  289. XM8@````)S971G9&]S`````+P````"<W1A<G1U<````````````GEE<W1E>'0`&
  290. XM```".`````)E>&ET7V1O<P```00````">65S:71E>'0```%.`````V)O9'EI*
  291. XM=&5X=````````28````#8F]D>71E>'0Q```````!=@````-C;&5A<F=D;W,`!
  292. XM``````#*`````VEN='5I;F%M90```````10````#>F)O9'ET97AT```````!=
  293. XMP@````-N8F]D>6ET97AT``````$Z`````VYZ8F]D>71E>'0``````@$`````K
  294. X$```#\@-NF
  295. X``
  296. Xend
  297. Xsize 1084
  298. END_OF_FILE
  299. if test 1559 -ne `wc -c <'gdostool.uu'`; then
  300.     echo shar: \"'gdostool.uu'\" unpacked with wrong size!
  301. fi
  302. # end of 'gdostool.uu'
  303. fi
  304. if test -f 'gdostool0.uu' -a "${1}" != "-c" ; then 
  305.   echo shar: Will not clobber existing file \"'gdostool0.uu'\"
  306. else
  307. echo shar: Extracting \"'gdostool0.uu'\" \(540 characters\)
  308. sed "s/^X//" >'gdostool0.uu' <<'END_OF_FILE'
  309. Xbegin 666 gdostool.doc.info
  310. XMXQ```0```````````"``'``%``,``0#%\-@`````````````````````````&
  311. XM````!```QA]Z`,7OXH````"````````````````````````````@`!P``@#%\
  312. XM[_@#````````````!___^`?___@&$)(8!S.3.`<PQS@',Y,X!S"3.`?___@$G
  313. XM```(!___^`?_?[@'_O-X!_S-.`?Z,M@'_W^X!][S>`<DS3@/FC+8#WO]^`[WY
  314. XMF_@9)FGX'-&6^#____A____X#___^````````````````````````````>]MZ
  315. XMY@#,;,8`SSC&`,QLQ@#/;,8````&`___]@````8``(!&``$,A@`#,L8`!<TF_
  316. XM``"`1@`A#(8`VS+&`&7-+@"$`@X!"&0.!MF6'@,N:1X````^````_@____X#0
  317. XG___^``````````9C.F-E9``````(````#D9)3$5465!%/51E>'0`E
  318. X``
  319. Xend
  320. Xsize 354
  321. END_OF_FILE
  322. if test 540 -ne `wc -c <'gdostool0.uu'`; then
  323.     echo shar: \"'gdostool0.uu'\" unpacked with wrong size!
  324. fi
  325. # end of 'gdostool0.uu'
  326. fi
  327. if test -f 'gdostool1.uu' -a "${1}" != "-c" ; then 
  328.   echo shar: Will not clobber existing file \"'gdostool1.uu'\"
  329. else
  330. echo shar: Extracting \"'gdostool1.uu'\" \(532 characters\)
  331. sed "s/^X//" >'gdostool1.uu' <<'END_OF_FILE'
  332. Xbegin 666 gdostool.info
  333. XMXQ```0`````!7@"9`",`$0`%``,``0#"W<``````````````````````````(
  334. XM`````\,`P%-P`````````4X```".``%ZX`````````^@````+@%R`)?__P``F
  335. XM```"0`)_``%=!```````P!*`````````````6@`H_____P`!____Z0``````<
  336. XM`````",`$``"``%\H`,```````!__\````!_X<````!_X<````!_X<````!_R
  337. XM_\````````````````````/ZJ/````/U1'@```/JHC@```/5<1@```.J__@`4
  338. XM``-5__@```*K__@```/___@``````````/____^``/_____``/_____@`/__^
  339. XM___@`/_____@`/_____@`/_____@`/P']0_@`/P.ZH?@`/P=U4?@`/P[BJ?@1
  340. XD`/QW``?@`/SN``?@`,W<``?@`/P```?@``````````````$`?
  341. X``
  342. Xend
  343. Xsize 351
  344. END_OF_FILE
  345. if test 532 -ne `wc -c <'gdostool1.uu'`; then
  346.     echo shar: \"'gdostool1.uu'\" unpacked with wrong size!
  347. fi
  348. # end of 'gdostool1.uu'
  349. fi
  350. echo shar: End of archive 1 \(of 1\).
  351. cp /dev/null ark1isdone
  352. MISSING=""
  353. for I in 1 ; do
  354.     if test ! -f ark${I}isdone ; then
  355.     MISSING="${MISSING} ${I}"
  356.     fi
  357. done
  358. if test "${MISSING}" = "" ; then
  359.     echo You have the archive.
  360.     rm -f ark[1-9]isdone
  361. else
  362.     echo You still need to unpack the following archives:
  363.     echo "        " ${MISSING}
  364. fi
  365. ##  End of shell archive.
  366. exit 0
  367. -- 
  368. Mail submissions (sources or binaries) to <amiga@uunet.uu.net>.
  369. Mail comments to the moderator at <amiga-request@uunet.uu.net>.
  370. Post requests for sources, and general discussion to comp.sys.amiga.
  371.