[comp.binaries.mac] Macintosh Technical Notes - 187 ioPosOffset

bytebug@dhw68k.cts.com (Roger L. Long) (05/29/88)

[187: Don't Look at ioPosOffset]

The Device Manager chapter of Inside  Macintosh  Volume  II  says
that  ioPosOffset  is  passed  to  and returned by Read and Write
calls.   It  also  says  that  "After  the  read  [or  write]  is
completed, the position is returned in ioPosOffset..."  Actually,
ioPosOffset is not changed by either call.

Also  note  that  device  drivers  should  only   look   at   the
dCtlPosition  field  of  the DCE, and should not look directly at
the ioPosOffset field of the parameter block.  The Device Manager
sets up dCtlPosition for the driver, taking into account both the
ioPosMode and the ioPosOffset.

---
(This file must be converted with BinHex 4.0)

:$c%i0b"TEe"[FdpQCR0PG!"A6e*%68&$33#3"!HU!!!$%BEp!!B!$J!#!!-!N!2
r!2rrr!!"!!!(SJ!)!!J!!!I-!!J!#!!!$AB!%!!#!*!$5!")!*!%!YS#+2rKrq)
#q3*'!`F&+!2m!!)!N!0)!%J!N!3#fJ)S!!%!N!0N!*!$!3!"N!-!N!-"*`m!!3!
"!!)i@!!#11$rr`#3"4N"N!!!N#%#!$d!!J!p!*!$!3!!"GS!-!!!"FS!%!!-!1h
rmJ"qrr)"52q3#J!"!*!$!3#3"3%!!!B5!#!!!!B+!!MrmJ!Hrr)!l2rb!EVrN!S
!!3#3!`%!N!8"!!!'`J$J!!!'-J#3!2rb!"lrmJ$Xrr)"Z[q3"3!*!!!9!!m!+!!
[!!N"l`!#!*!$#3$6rKm"l`([CA)JDA-JC(*KCfGTEL!JG!!"$@8!"J!!#J!!&3!
pp8(,0mDJp18K$b2c(cMcI`RQpR%!N!-&d2-I#I4&2p8Jp-9ID`BJGI8&MdrGJ5!
!!!B!!!S!!"8!#3(K!!%!N!-*!@J'J!#3&`B!!!`!!!-!#3(Q!`3!N!-*!#J!H3%
r!Fm#%!)3EL"TFb"KEQ&XEfG[!'"IN&m0!!B!!!N!!"8!(I6@ac*BX29"bcI'S26
P)Bm*m*r`m0!!$!!!$J%!&3!E'"%!&`!"$@8!"J!!$J!!&3!JmMmamimhmk$d46r
9)26&AfX')(Ae"Bp2hB%[$3!'!!!1!!!9!!%0r`!'!!!1!!!9!"he-4"UKI1[#I9
,%24"pfI"$deMEfF8m0!!"J!!$J!!&3!"$3%!"J!!$J!!&3!QpA4b)6$f,hRcV`R
d4NF`p"QK6`Rd(NHJmbmX$c(cRcMcM`d!!!B!!!i!!"8!B&q3A`d!"J!!#3!!&3!
"$3!!"J!!$J!!&3%@p"U&!e)3+f)*(hCm%*4rGK5!LepeU38kpj!!T9pV"L!V%*p
$+[8&KbG6$A'T"G!V%2423r4I,!Bj#,Ah@T!!05#PAfX*G"`Upj!!BJ+a"ep3@26
pf")0FDN&d#X3jNEfd5&!pLTFpVmZ$e5a$d3IGR`3p0BfpR&!J5J2GH#I3bVe"BF
R8`e8!V%*4rGK6b`#EfYcpR"c*3E-Ah8b$f*5X#X3GI8&MdeC%'13!#X3GI8&Mdr
GJ5mZ!!"1!!!-!!!9!#8-!3!9!#N-!!!9!$B-!!!@!%)-!!!9!(N-!!!@!)3-!!!
9!,i-!!!@!-S-!!!9!2J-!!!@!3%-!!!9!3S-!!!@!48-!!!9!!%0"J!'!!!-!!!
9!4ce5a$d3IGR`3p0BfpR&!bfiK3&d256Kj%26@ac*BX29PVhAfd3p*p*#'pjJ#Y
L"ep3@26pf")(J1D)'3*3Bj!!35pe3aN2B[H3!28KD3Bj$eG()3aUU2,Jp*)'U&#
'pjJ#YL$p,d(5&!+a""D3!2@e32GdFKpG"i$&pYkK)CmX!V%1@(*e-(J%%[G8-C!
!F`GI8&MdrGJ5r*r6$d(#peDUpjmX"ep3@26pf")(J$8Jbf2fFC!!pLpj!A+a3-D
UmZm0!()!!!`!!"8!(J`#!"8!1!`!!"8!3``!!"B!6J`!!"8!A!`"!"8!A``!!"8
!B!`"!"8!D!`!!"8!D3`"!"8!D``!!"8!E!`!!"B!F!`!!"8!G3`!!"B!HJ`!!"8
!f3`!!"B!j!`!!"8!m3`!!"B!r!`!!"8!N!-"$!`!!3`-!*!,&*c))!!"-!!L!*!
$$!#3!a5G)#!!!9)!$$)"!!`!$!!6IMJS!!&H!$Sb!3#3!`%3%!#3"a5G"#!!!CJ
!)J#3!a!!N!-6IN`J!!'k!!SV!3#3!`%,#`!"("`!!3m2!!%2$`!"$`m!!3m2!!%
2$`!"$`m!!3X,!!%2$`!#$S3!!3i1!!)1K!#3Aa0q+#!!!F3!)J#3!`X!N!-8&6!
J!!(Q!'Sa!3!F!!X!&"3)+!!#8!!Q!!)!$`!R!"36p#!!!RB!$$3"!!m!0J!6IL!
S!!+#!#Bd!3!2!%8!%hh`)!!#U!!-0!%!$`"8!"36H#J!!V3!)M3"!!m!B`!8R6!
J!!,@!!`d!3!2!()!%hhS+!!#iJ!Z0!%!#`#"!"0q%#!!!a!!DM%"!!m!M!!8&,3
J!!0k!!`d!3!i!*X!&"2J+!!%Q!%b!`!!$J$6!"5G1#!!")`!$$-"!$J!i3!8&+J
S!!1'!3B$!*!$"kS!3F!UP68!!!%!N!-#X`!!!E-!N!0HEQ4[Gb`*#5#3"AYcG'p
bCA-JG'KP)(GTEQ4[Ge"d$c%i0b"TEe"[FdpQCR0PG!)!N!0A6e*%68&$33#3"PG
28N40380"!*!&l3#3%!S+0G(bIJ!!"kS!!!-4Eh)JG'KP)%&`F'aTBbiJC(9bD@j
R)(9`C'&dCA0p$5!J4'PbC@0dEh*j)$SJ9fPZC'ph8(4b1`NJN!9l9fPZC'ph)'C
[FL"NC@CKG@ad)'4TFfXJC'PbC@0dEh*jI3d0)#"cBh*PC@iX#C!$)*!&Hh*PBh4
KEQGXC5"dD'&d!!!"6!C6G@jNBAN!N!N'6@pZC'&j!*!*"e4eCA0NBAN!N!J*9f9
NEQ9cC'&j!*!'#&4SGA*cC'&j!*!("NCbD@4KH3#3#3K6BA4eFQ4KH3#3"`G+B@j
eBA*j!*!)#%CPBR*eBA*j!*!("8eKFQ0S!*!+"8&`FQPX!*!+!deKH3#3$!4+G@j
P!*!,"%TeE(N!N!X'3A9RGA0d!*!*#90PF(4PE@*PFJ#3"JG2Bh4[BQ9b!*!)#%j
[GQ9YBQ9b!*!(#%4PBf9YBQ9b!*!(rrm!!`#3"#`J!!!J!*!$,#!!N!F"6R8!N!-
B!!X!&`!@!"8!&!#3!`-!!J!%!!8!"J!(!*!$%!mJCA4ZFQpKDA0NE'KMCR!!N!-
[!!m!"`!,!*!$&J!$!"8!"J!-!"J!"!!#!!J!&`!8!!83%!3rN!-3*"!&2a!r2`J
!!!%!N!-#X`!!!E-!N!0H!"0qf!X'!*!$(!"H!!&*6P4-!*!$%P088L!!!J!H$YM
rrb!!N!F$)2rr!!!"8!#3"!+mrrm!!!&X!*!%!b(rr`!!!B!!&*eX"U):
---