arch/m68k-all/dos/bcpl_patches.c

   1 #include <aros/asmcall.h>
   2 #include <dos/dosextens.h>
   3 #include <exec/libraries.h>
   4 #include <proto/exec.h>
   5
   6 #include "bcpl.h"
   7
   8 /* CallGlobVec lives in the private function (4) */
   9 AROS_UFP5(LONG, CallGlobVec,
  10     AROS_UFPA(LONG, function, D0),
  11     AROS_UFPA(LONG, d1, D1),
  12     AROS_UFPA(LONG, d2, D2),
  13     AROS_UFPA(LONG, d3, D3),
  14     AROS_UFPA(LONG, d4, D4));
  15
  16
  17 /* LoadSeg() needs D1-D3 parameters for overlay hunk support */
  18 AROS_UFP4(BPTR, LoadSeg_Overlay,
  19     AROS_UFPA(UBYTE*, name, D1),
  20     AROS_UFPA(BPTR, hunktable, D2),
  21     AROS_UFPA(BPTR, fh, D3),
  22     AROS_UFPA(struct DosLibrary *, DosBase, A6));
  23
  24 extern void *BCPL_jsr, *BCPL_rts;
  25 extern const ULONG BCPL_GlobVec[(BCPL_GlobVec_NegSize + BCPL_GlobVec_PosSize) >> 2];
  26
  27 const UWORD highfunc = 37, lowfunc = 5, skipfuncs = 2;
  28
  29 #define PATCHMEM_SIZE (10 * (highfunc - lowfunc + 1 - skipfuncs) * sizeof(UWORD) + 16 * sizeof(UWORD))
  30
  31 /* This patches two compatibility problems with badly written programs:
  32  * 1) Return value in both D0 and D1.
  33  * 2) 1.x original DOS functions can be called without DOSBase in A6.
  34  * Both "features" are original BCPL DOS side-effects.
  35  */
  36
  37 static int PatchDOS(struct DosLibrary *dosbase)
  38 {
  39     UWORD i;
  40     UWORD *asmcall, *asmmem;
  41     IPTR func;
  42     APTR GlobVec;
  43
  44     GlobVec = AllocMem(BCPL_GlobVec_NegSize + BCPL_GlobVec_PosSize, MEMF_PUBLIC);
  45     if (GlobVec == NULL)
  46         return FALSE;
  47
  48     CopyMem(BCPL_GlobVec, GlobVec, BCPL_GlobVec_NegSize + BCPL_GlobVec_PosSize);
  49     GlobVec += BCPL_GlobVec_NegSize;
  50     *(APTR *)(GlobVec + GV_DOSBase) = dosbase;
  51
  52     Forbid();
  53
  54     /* Use this private slot for the C-to-BCPL thunk */
  55     __AROS_INITVEC(dosbase, 4);
  56     __AROS_SETVECADDR(dosbase, 4, CallGlobVec);
  57
  58     asmmem = asmcall = AllocMem(PATCHMEM_SIZE, MEMF_PUBLIC);
  59
  60     for (i = lowfunc; i <= highfunc; i++)
  61     {
  62         if (i == 24 || i == 25)
  63             continue;
  64         func = (IPTR)__AROS_GETJUMPVEC(dosbase, i)->vec;
  65         __AROS_SETVECADDR(dosbase, i, asmcall);
  66         *asmcall++ = 0x2f0e; // MOVE.L A6,-(SP)
  67         *asmcall++ = 0x4df9; // LEA dosbase,A6
  68         *asmcall++ = (UWORD)((ULONG)dosbase >> 16);
  69         *asmcall++ = (UWORD)((ULONG)dosbase >>  0);
  70         *asmcall++ = 0x4eb9; // JSR func
  71         *asmcall++ = (UWORD)(func >> 16);
  72         *asmcall++ = (UWORD)(func >>  0);
  73         *asmcall++ = 0x2C5F; // MOVE.L (SP)+,A6
  74         *asmcall++ = 0x2200; // MOVE.L D0,D1
  75         *asmcall++ = 0x4e75; // RTS
  76     }
  77
  78     /* Redirect LoadSeg() to LoadSeg_Overlay() if D1 == NULL */
  79     func = (IPTR)__AROS_GETJUMPVEC(dosbase, 25)->vec;
  80     __AROS_SETVECADDR(dosbase, 25, asmcall);
  81     *asmcall++ = 0x2f0e; // MOVE.L A6,-(SP)
  82     *asmcall++ = 0x4df9; // LEA dosbase,A6
  83     *asmcall++ = (UWORD)((ULONG)dosbase >> 16);
  84     *asmcall++ = (UWORD)((ULONG)dosbase >>  0);
  85     *asmcall++ = 0x41f9; // LEA func,A0
  86     *asmcall++ = (UWORD)(func >> 16);
  87     *asmcall++ = (UWORD)(func >>  0);
  88     *asmcall++ = 0x4a81; // TST.L D1
  89     *asmcall++ = 0x6606; // BNE.B +6 (D1 not NULL = normal LoadSeg)
  90     *asmcall++ = 0x41f9; // LEA LoadSeg_Overlay,A0
  91     *asmcall++ = (UWORD)((ULONG)LoadSeg_Overlay >> 16);
  92     *asmcall++ = (UWORD)((ULONG)LoadSeg_Overlay >>  0);
  93     *asmcall++ = 0x4e90; // JSR (A0)
  94     *asmcall++ = 0x2C5F; // MOVE.L (SP)+,A6
  95     *asmcall++ = 0x2200; // MOVE.L D0,D1
  96     *asmcall++ = 0x4e75; // RTS
  97
  98     CacheClearE(asmmem, PATCHMEM_SIZE, CACRF_ClearI|CACRF_ClearD);
  99
 100     dosbase->dl_A5 = (LONG)&BCPL_jsr;
 101     dosbase->dl_A6 = (LONG)&BCPL_rts;
 102     dosbase->dl_GV = (APTR)GlobVec;
 103
 104     Permit();
 105
 106     return TRUE;
 107 }
 108
 109 ADD2INITLIB(PatchDOS, 0)
 110
 111 static int UnPatchDOS(struct DosLibrary *dosbase)
 112 {
 113     APTR asmcall;
 114
 115     asmcall = __AROS_GETJUMPVEC(dosbase, lowfunc)->vec;
 116     FreeMem(asmcall, PATCHMEM_SIZE);
 117     FreeMem(dosbase->dl_GV - BCPL_GlobVec_NegSize, BCPL_GlobVec_NegSize + BCPL_GlobVec_PosSize);
 118
 119     return TRUE;
 120 }
 121
 122 ADD2EXPUNGELIB(UnPatchDOS, 0)