* Switch.a -- TrackSalve * * # date by Comment * -- --------- ---- --------------------- * 0 29-Oct-89 DWR Created for Tracksalve * * nolist INCLUDE "Call.i" INCLUDE "ts.i" INCLUDE "exec/tasks.i" INCLUDE "exec/resident.i" * list CSECT text,code,0,1,2 Any xref's after this are 16-bit reloc ********************************************************* * * PCtoTS * * We need to catch Trackdisk in its highest task-loop. Otherwise we could lose control * after an rts. This loop is rather small: 7 instuctions. One of the instructions is a * jsr _LVOWait(a6). Trackdisk is waiting here for a timer or an IORequest and will be here * most of the time. If we change the return address to our code, Trackdisk smoothly enters * our code. We change this address only if TD is at this point. * * Input: a0 UnitData structure * * Output: d0 0 if caught else E_CATCHTD * * Usage: d2 PC of TD-task at the point where we want to change it * d6 Timeout counter * d7 Error * * a2 TSControl structure * a3 UnitData structure * a5 Task stucture of Trackdisk unit task * * NB! We are accessing the TSControl structure in a way that needs protection. * Func PCtoTS,@PCtoTS movem.l d2/d3/d6/d7/a2/a3/a5,-(a7) moveq.l #0,d7 No error for now move.l a0,a3 UnitData structure move.l UD_TDReq+IO_UNIT(a3),a5 Lea Unit structure of the Trackdisk IORequest move.b TDU_UnitNr(a5),d3 Get unit number (to set InUse flag later) move.l MP_SIGTASK(a5),a5 Lea Task control block associated with this port move.l UD_TSControl(a3),a2 Control structure move.l TSC_TDTag(a2),d2 Begin of TD code add.l #$1592,d2 Add offset of desired return address moveq.l #25,d6 We put a limit here, so we will not hang forever if TD is dead CheckPC ExCall Forbid Prevent TD to become active move.l TC_SPUPPER(a5),a0 Initial stackpointer of TD cmp.l WaitRtnPC(a0),d2 Is TD on the desired spot? beq.s ChangePC Yes, change the return address.. LibCall Permit No, give TD a chance to change its situation moveq.l #10,d1 We will wait for a fifth of a second DOSCall Delay Sleeping dbra d6,CheckPC And try again.. moveq.l #E_CATCHTD,d7 But not forever, so set error bra.s PCtoTSRtn Quit.. ChangePC move.l d2,UD_ReturnTD(a3) Save original TD address move.l TSC_TSCode(a2),WaitRtnPC(a0) Change return addres to adress in our code move.l TC_Userdata(a5),UD_Userdata(a3) Keep original value (although TD does not use it) move.l a3,TC_Userdata(a5) Make UnitData structure known to TD-task bset.b d3,TSC_InUse(a2) Set flag to prevent freeing the TSControl structure LibCall Permit Multitasking on again PCtoTSRtn move.l d7,d0 Error movem.l (a7)+,d2/d3/d6/d7/a2/a3/a5 rts ********************************************************* * * RelocateTS * * Modify position dependend values in copied TSCode * * Input: a0 TSControl structure * Func RelocateTS,@RelocateTS move.l TSC_TSCode(a0),a0 lea.l TSCodeRelocTable(pc),a1 10$ move.w (a1)+,d0 beq.s 20$ move.l a0,d1 add.l 0(a0,d0.w),d1 move.l d1,0(a0,d0.w) bra.s 10$ 20$ rts xref TSCodeRelocTable ********************************************************* * * RelocateTD * * Modify position dependend values in relocated Trackdisk code versions 33.127 and 34.1 * * Input: a0 TSControl structure * ifd __stdargs Func _RelocateTD move.l 4(a7),a0 endc Func RelocateTD,@RelocateTD move.l TSC_TSTag(a0),a1 Begin of copy of Trackdisk code move.l TSC_TDTag(a0),d0 Begin of Trackdisk code (in ROM) * cmp.l a1,RT_MATCHTAG(a1) Does our copy has its self-pointer right? * beq.s RelocateRtn Yes, already relocated.. sub.l a1,d0 TD org minus TD copy = relocation value lea.l RelocTable(pc),a0 Table of relative addresses to relocate bra.s Relocate20 Enter loop.. Relocate10 sub.l d0,0(a1,d1.w) Only Amiga makes it possible! Relocate20 move.w (a0)+,d1 Get offset in TD-code bne.s Relocate10 RelocateRtn rts *-- You can obtain this table by comparing version 1.2 and 1.3 and do some editing on the result RelocTable dc.w $0002 dc.w $0006 dc.w $000E dc.w $0012 dc.w $0016 dc.w $0324 dc.w $032A dc.w $03C0 dc.w $091C dc.w $0940 dc.w $0966 dc.w $0980 dc.w $0994 dc.w $09B6 dc.w $09C4 dc.w $09CC dc.w $0A00 dc.w $0A04 dc.w $0A08 dc.w $0A0C dc.w $0A10 dc.w $0A14 dc.w $0A1C dc.w $0A20 dc.w $0A24 dc.w $0A28 dc.w $0A2C dc.w $0A30 dc.w $0A34 dc.w $0A38 dc.w $0A3C dc.w $0A40 dc.w $0A44 dc.w $0A48 dc.w $0A4C dc.w $0A50 dc.w $0A54 dc.w $0A58 dc.w $0A5C dc.w $0A60 dc.w $0A64 dc.w $0A68 dc.w $0A6C dc.w $0A70 dc.w $127E dc.w $12EA dc.w $1316 dc.w $1352 dc.w $1386 dc.w $13E4 dc.w $1446 dc.w $1690 dc.w $16B8 dc.w $195A dc.w $19A2 dc.w $19B2 dc.w 0 ********************************************************* * * PatchMem * * Change memory according to a table * * Input: a0 Memory to change * a1 Patchtable (Offset.w, Size.w, Patch.w[Size]) * Func PatchMem,@PatchMem movem.l a2,-(a7) move.l a0,a2 Lea begin of memory GetNextPatch move.l a2,a0 Begin of memory move.w (a1)+,d0 Get offset in code to put patch add.w d0,a0 Lea destination of patch move.w (a1)+,d1 Get size of patch in words beq.s PatchMemRtn No patch, done.. bra.s CopyPatch10 Enter copyloop CopyPatch move.w (a1)+,(a0)+ Copy word of code CopyPatch10 dbra d1,CopyPatch Loop .. bra.s GetNextPatch Examine next entry in Patchtable PatchMemRtn movem.l (a7)+,a2 rts ********************************************************* END