v4.0/src/MAPPER/SIGHAND.ASM

   1 page 80,132
   2
   3 title CP/DOS DosSetSigHandler  mapper
   4
   5         include msc.inc
   6
   7 dosxxx  segment byte public 'dos'
   8         assume  cs:dosxxx,ds:nothing,es:nothing,ss:nothing
   9
  10 ;**********************************************************************
  11 ;*
  12 ;*   MODULE:   dossetsighandler
  13 ;*
  14 ;*   FILE NAME: dos007.asm
  15 ;*
  16 ;*   CALLING SEQUENCE:
  17 ;*
  18 ;*       push      word    file handle
  19 ;*       push      dword   distance
  20 ;*       push      word    move type
  21 ;*       push@     dword   new pointer
  22 ;*       call      doschgfileptr
  23 ;*
  24 ;*   MODULES CALLED:  PC-DOS Int 21h, ah=42h
  25 ;*
  26 ;*********************************************************************
  27
  28             public   dossetsighandler
  29             .sall
  30             .xlist
  31             include  macros.inc
  32             .list
  33
  34 str         struc
  35 old_bp      dw       ?
  36 return      dd       ?
  37 Signumber   dw       ?          ; signal number
  38 Action      dw       ?          ; action code
  39 Prevaction  dd       ?          ; previous action code
  40 Prevadrs    dd       ?          ; previous vector address
  41 Routineadrs dd       ?          ; interrupt handler address
  42 str         ends
  43
  44 ; While we hate to do this, we have to.  The following data areas are
  45 ; expected to be in the CODE segment.
  46
  47 NextControlBreakHandler         label   dword
  48 NextControlBreakHandlerOffset   dw      DummyControlBreakHandler
  49 NextControlBreakHandlerSegment  dw      dosxxx
  50
  51 NextCriticalErrorHandler        label   dword
  52 NextCriticalErrorHandlerOffset  dw      DummyCriticalErrorHandler
  53 NextCriticalErrorHandlerSegment dw      dosxxx
  54
  55 dossetsighandler  proc  far
  56
  57         Enter    dossetsighandler       ; push registers
  58
  59         mov      ax,[bp].action         ; get action code
  60         cmp      ax,2                   ; action code 2 ??
  61         je       continue1              ; branch if true
  62         mov      ax,1                   ; else, set error code
  63         jmp      exit                   ; return
  64
  65 continue1:
  66         mov      ax,[bp].signumber      ; get signel number
  67         cmp      ax,1                   ; signal 1 (cntrl chara) ??
  68         je       cntrlc                 ; jump if true
  69         cmp      ax,4                   ; signal 4 (cntrl chara) ??
  70         je       cntrlc                 ; jump if true
  71         mov      ax,2                   ; else, set error code
  72         jmp      exit                   ; return
  73
  74 cntrlc: mov      ax,03523h
  75         int      21h                    ; get old vector address
  76
  77         lds      si,[bp].prevadrs       ; previous handler pointer
  78         mov      word ptr [si],bx       ; save it in prevsdrs
  79         mov      word ptr [si]+2,es
  80
  81         lds      dx,[bp].routineadrs    ; get address of signal  handler
  82
  83         mov     NextControlBreakHandlerOffset,dx   ; save it
  84         mov     NextControlBreakHandlerSegment,ds
  85
  86         mov     dx,cs
  87         mov     ds,dx
  88         mov     dx,offset RealControlBreakHandler
  89
  90         mov      ax,02523H
  91         int      21h                   ; set signal handler addrs in vector
  92
  93         sub      ax,ax                 ; set good return code
  94
  95 exit:   mexit                          ; pop registers
  96         ret      size str - 6          ; return
  97
  98 dossetsighandler  endp
  99
 100         page
 101
 102 ;------------------------------------------------------------------------------
 103
 104 ; This routine will get control on  control break, and it will make
 105 ;  sure that the environment is acceptable prior to calling the new
 106 ;  handler.  NOTE: we expect the new handler to be written in MicroSoft 'C'
 107
 108 RealControlBreakHandler         proc    far
 109
 110         push    ds
 111         push    es
 112         push    di
 113         push    si
 114         push    bp
 115         push    dx
 116         push    cx
 117         push    bx
 118         push    ax
 119
 120 ; reestablish the es and ds segment registers before going to 'C'
 121
 122         mov     ax,seg DGroup
 123         mov     ds,ax
 124         mov     es,ax
 125
 126         call    NextControlBreakHandler
 127
 128         pop     ax
 129         pop     bx
 130         pop     cx
 131         pop     dx
 132         pop     bp
 133         pop     si
 134         pop     di
 135         pop     es
 136         pop     ds
 137
 138         iret
 139
 140 RealControlBreakHandler         endp
 141
 142         page
 143
 144 ;------------------------------------------------------------------------------
 145
 146 ; This routine will get control on the control break, and it will make
 147 ;  sure that the environment is acceptable prior to calling the new
 148 ;  handler.  NOTE: we expect the new handler to be written in MicroSoft 'C'
 149
 150 RealCriticalErrorHandler        proc    far
 151
 152         push    ds
 153         push    es
 154         push    di
 155         push    si
 156         push    bp
 157         push    dx
 158         push    cx
 159         push    bx
 160         push    ax
 161
 162 ; reestablish the es and ds segment registers before going to 'C'
 163
 164         mov     ax,seg DGroup
 165         mov     ds,ax
 166         mov     es,ax
 167
 168         call    NextControlBreakHandler
 169
 170         pop     ax
 171         pop     bx
 172         pop     cx
 173         pop     dx
 174         pop     bp
 175         pop     si
 176         pop     di
 177         pop     es
 178         pop     ds
 179
 180         iret
 181
 182 RealCriticalErrorHandler        endp
 183
 184         page
 185
 186 ;------------------------------------------------------------------------------
 187
 188 DummyControlBreakHandler        proc    far
 189
 190                 iret
 191
 192 DummyControlBreakHandler        endp
 193
 194 DummyCriticalErrorHandler       proc    far
 195
 196                 iret
 197
 198 DummyCriticalErrorHandler       endp
 199
 200
 201
 202 dosxxx      ends
 203
 204             end