Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!mit-eddie!uw-beaver!ubc-cs!van-bc!rsoft!mindlink!a186
From: a186@mindlink.UUCP (Harvey Taylor)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Create Port
Message-ID: <409@mindlink.UUCP>
Date: 23 Jul 89 17:27:23 GMT
Organization: MIND LINK! - British Columbia, Canada
Lines: 71


   Some time ago somebody was wondering about what CreatePort
 in Amiga.Lib _really_does. Included below is a disassembly
 I did with Metascope & a stub program. This method is extendable
 to any other functions there you are interested in...
<-Harvey
*
*       _Createport in Amiga.lib
*
  | _CreatePort
  |    MOVEM.L D2-D5/A2,-(A7)         * Save some regs
  |    MOVE.L  $18(A7),D3             * Name
  |    MOVE.B  $1F(A7),D2             * Priority
  |    MOVEQ   #-1,D5                 * Any Signal
  |    MOVE.L  D5,-(A7)
  |    JSR     _AllocSignal
  |    MOVE.B  D0,D1
  |    MOVEQ   #0,D0                  * clear top
  |    MOVE.B  D1,D0
  |    MOVE.L  D0,D4                  * copy sigbit
  |    MOVEQ   #-1,D1
  |    CMP.L   D0,D1                  * any sigbit?
  |    ADDQ.L  #4,A7
  |    BNE.S   .L8                    * If ok:
  |    MOVEQ   #0,D0                  * Signal error
  |    BRA.S   .L1                    * exit
  | .L8
  |    MOVE.L  #$10001,-(A7)          * MEMF_CLEAR|MEMF_PUBLIC
  |    PEA     $22                    * Size
  |    JSR     _AllocMem
  |    MOVEA.L D0,A2                  * COPY BASE
  |    MOVE.L  A2,D5
  |    ADDQ.L  #8,A7                  * FIX STACK
  |    BNE.S   .L7                    * IF OK:
  |    MOVE.L  D4,-(A7)               * ELSE
  |    JSR     _FreeSignal            * FREE SIGNAL
  |    MOVEQ   #0,D0
  |    ADDQ.L  #4,A7
  |    BRA.S   .L1                    * EXIT
  | .L7
  |    MOVE.L  D3,$A(A2)              * INSERT LN.NAME
  |    MOVE.B  D2,9(A2)               * INSERT LN.PRI
  |    MOVE.B  #4,8(A2)               * INSERT LN.TYPE = NT_MSGPORT
  |    CLR.B   $E(A2)                 * CLEAR  MP.FLAGS
  |    MOVE.B  D4,$F(A2)              * INSERT MP.SIGBIT
  |    CLR.L   -(A7)
  |    JSR     _FindTask
  |    MOVE.L  D0,$10(A2)             * INSERT MP.SIGTASK
  |    TST.L   D3                     * IS THERE A NAME?
  |    ADDQ.L  #4,A7
  |    BEQ.S   .L6                    * IF NO:
  |    MOVE.L  A2,-(A7)               * If a Name Use AddPort()
  |    JSR     _AddPort
  |    BRA.S   .L12
  | .L6
  |    PEA     $14(A2)                * If no name use NewList
  |    JSR     _NewList
  | .L12
  |    ADDQ.L  #4,A7
  |    MOVE.L  A2,D0                  * RETURN D0 = BASE OF MSGPORT
  | .L1
  |    MOVEM.L (A7)+,D2-D5/A2         * restore regs
  |    RTS
*
*
*
 "Like some creature from a horror film, the IC that Bill Gates called
                         `brain damaged' refuses to die." - RE Aug/89
  Harvey Taylor      Meta Media Productions   ///
  uunet!van-bc!rsoft!mindlink!Harvey_Taylor  ///
  a186@mindlink.UUCP                       >X/