virt_ports.asm

   1 ;    Virtual Ports for the BIOS Interaction
   2 ;
   3 ;    Copyright (C) 2010 Frank Zoll
   4 ;
   5 ;    This file is part of avrcpm.
   6 ;
   7 ;    avrcpm is free software: you can redistribute it and/or modify it
   8 ;    under the terms of the GNU General Public License as published by
   9 ;    the Free Software Foundation, either version 3 of the License, or
  10 ;    (at your option) any later version.
  11 ;
  12 ;    avrcpm is distributed in the hope that it will be useful,
  13 ;    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 ;    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 ;    GNU General Public License for more details.
  16 ;
  17 ;    You should have received a copy of the GNU General Public License
  18 ;    along with avrcpm.  If not, see <http://www.gnu.org/licenses/>.
  19 ;
  20 ;    $Id$
  21 ;
  22
  23
  24 ; ---------------- Defines for the Virtual peripherial interface -------
  25
  26 ;The hw is modelled to make writing a CPM BIOS easier.
  27 ;Ports:
  28 ;0      - Con status. Returns 0xFF if the UART has a byte, 0 otherwise.
  29 ;1      - Console input, aka UDR.
  30 ;2      - Console output
  31 ;3      - "UART" status: bit 0=rx, bit 1 = tx
  32 ;4      - "UART" data register, no wait
  33 ;15     - Disk select
  34 ;16,17  - Track select
  35 ;18     - Sector select
  36 ;20     - Write addr l
  37 ;21     - Write addr h
  38 ;22     - Trigger - write  to read, to write a sector using the above info;
  39 ;                       , write to allocated/dirctory/unallocated
  40
  41 ;----------------------------------------------- Start of Data Segment
  42
  43         .dseg
  44
  45
  46 ; ---------------------------------------------- Start of Code Segment
  47         .cseg
  48
  49 uartstat:
  50         clr     temp
  51         lds     temp2,rxcount
  52         cpse    temp2,_0
  53          sbr    temp,0x01
  54         lds     temp2,txcount
  55         cpi     temp2,TXBUFSIZE
  56         breq    uartst_1
  57          sbr    temp,0x02
  58 uartst_1:
  59         ret
  60
  61 uartout:
  62         lds     temp2,txcount
  63         cpi     temp2,TXBUFSIZE
  64         breq    uartout_1
  65         rjmp uartputc
  66 uartout_1:
  67         ret
  68
  69 uartin:
  70         clr     temp
  71         lds     temp2,rxcount
  72         cpse    temp2,_0
  73          rjmp   uartgetc
  74         ret
  75
  76 conStatus:
  77         lds     temp,rxcount
  78         cpse    temp,_0
  79          ldi    temp,0xff
  80         ret
  81
  82 conInp:
  83         rjmp uartgetc
  84
  85 dbgOut:
  86         printnewline
  87         printstring "Debug: "
  88         rcall printhex
  89         ret
  90
  91 conOut:
  92         rjmp uartputc
  93
  94 ;Called with port in temp2. Should return value in temp.
  95 portRead:
  96         cpi temp2,0
  97         breq conStatus
  98         cpi temp2,1
  99         breq conInp
 100         cpi     temp2,3
 101         breq    uartstat
 102         cpi     temp2,4
 103         breq    uartin
 104
 105         cpi     temp2,15
 106         breq    dskDiskCheck
 107         cpi     temp2,22
 108         breq    dskErrorRet
 109
 110         cpi     temp2,TIMER_MSECS
 111         brlo    pr_noclock
 112         cpi     temp2,TIMER_MSECS+6
 113         brsh    pr_noclock
 114         rjmp    clockget
 115
 116 pr_noclock:
 117         ldi     temp,0xFF
 118         ret
 119
 120 ;Called with port in temp2 and value in temp.
 121 portWrite:
 122         cpi temp2,0
 123         breq dbgOut
 124         cpi temp2,2
 125         breq conOut
 126         cpi temp2,4
 127         breq uartout
 128
 129         cpi temp2,15
 130         breq dskDiskSel
 131         cpi temp2,16
 132         breq dskTrackSel_l
 133         cpi temp2,17
 134         breq dskTrackSel_h
 135         cpi temp2,18
 136         breq dskSecSel
 137         cpi temp2,20
 138         breq dskDmaL
 139         cpi temp2,21
 140         breq dskDmaH
 141
 142         cpi temp2,22
 143         breq dskDoIt
 144
 145         cpi     temp2,TIMERPORT
 146         brlo    pw_noclock
 147         cpi     temp2,TIMER_MSECS+6
 148         brsh    pw_noclock
 149         rjmp    clockput
 150
 151 pw_noclock:
 152         ret
 153
 154
 155
 156
 157 ;---------------------------------------------------------------------