PIC JAL Routine

For access to PIC peripherals

by Wouter van Ooijen, extended to  further support '877 by  Vasile Surducan

-- --------------------------------------------------------------------
-- file      : jpicm.jal
-- author    : Wouter van Ooijen
-- date      : 02-APR-2000
-- purpose   : access to PIC peripherals
-- requires  : -
--
-- Copyright (C) 1998, 2000 Wouter van Ooijen
--
-- This library is free software; you can redistribute it and/or
-- modify it under the terms of the GNU Library General Public
-- License as published by the Free Software Foundation; either
-- version 2 of the License, or (at your option) any later version.
--
-- This library is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-- Library General Public License for more details.
--
-- You should have received a copy of the GNU Library General Public
-- License along with this library; if not, write to the
-- Free Software Foundation, Inc., 59 Temple Place - Suite 330,
-- Boston, MA  02111-1307, USA.
--
-- after june 2000 adapted by V.Surducan for more 877
-- 02-APR-2000 adapted for 12c509a and 16F877
-- 17-DEC-1998 ???
-- --------------------------------------------------------------------


-- --------------------------------------------------------------------
-- some special function registers and bits within these registers
-- --------------------------------------------------------------------

var volatile byte indf         at  0
var volatile byte tmr0         at  1
var volatile byte pcl          at  2
var volatile byte status       at  3
var volatile byte fsr          at  4
var volatile byte port_a       at  5
var volatile byte port_b       at  6
var volatile byte port_c       at  7
var volatile byte port_d       at  8
var volatile byte port_e       at  9
var volatile byte x84_eedata   at  8
var volatile byte x84_eeadr    at  9
var volatile byte pclath       at 10
var volatile byte intcon       at 11

var volatile byte f877_t2con   at 0x12
var volatile byte f877_ccpr1l  at 0x15
var volatile byte f877_ccpr1h  at 0x16
var volatile byte f877_ccp1con at 0x17

var volatile byte f877_adcon1  at 0x9F
var volatile byte f877_adcon0  at 0x1F
var volatile byte f877_pr2     at 0x92
var volatile byte f877_adresl  at 0x9E
var volatile byte f877_adresh  at 0x1E

var volatile byte f877_eeadr   at 0x10D
var volatile byte f877_eedath  at 0x10E
var volatile byte f877_eeadrh  at 0x10F
var volatile byte f877_eedata  at 0x10C

var volatile byte f877_eecon1  at 0x18C
var volatile byte f877_eecon2  at 0x18D

-- pseudo-variable in bank 1
var volatile byte option

var volatile bit  pin_a0 at port_a : 0
var volatile bit  pin_a1 at port_a : 1
var volatile bit  pin_a2 at port_a : 2
var volatile bit  pin_a3 at port_a : 3
var volatile bit  pin_a4 at port_a : 4
var volatile bit  pin_a5 at port_a : 5

var volatile bit  pin_b0 at port_b : 0
var volatile bit  pin_b1 at port_b : 1
var volatile bit  pin_b2 at port_b : 2
var volatile bit  pin_b3 at port_b : 3
var volatile bit  pin_b4 at port_b : 4
var volatile bit  pin_b5 at port_b : 5
var volatile bit  pin_b6 at port_b : 6
var volatile bit  pin_b7 at port_b : 7

var volatile bit  pin_c0 at port_c : 0
var volatile bit  pin_c1 at port_c : 1
var volatile bit  pin_c2 at port_c : 2
var volatile bit  pin_c3 at port_c : 3
var volatile bit  pin_c4 at port_c : 4
var volatile bit  pin_c5 at port_c : 5
var volatile bit  pin_c6 at port_c : 6
var volatile bit  pin_c7 at port_c : 7

var volatile bit  pin_d0 at port_d : 0
var volatile bit  pin_d1 at port_d : 1
var volatile bit  pin_d2 at port_d : 2
var volatile bit  pin_d3 at port_d : 3
var volatile bit  pin_d4 at port_d : 4
var volatile bit  pin_d5 at port_d : 5
var volatile bit  pin_d6 at port_d : 6
var volatile bit  pin_d7 at port_d : 7

var volatile bit  pin_e0 at port_e : 0
var volatile bit  pin_e1 at port_e : 1
var volatile bit  pin_e2 at port_e : 2

var volatile bit  status_c    at status : 0
var volatile bit  status_dc   at status : 1
var volatile bit  status_z    at status : 2
var volatile bit  status_pd   at status : 3
var volatile bit  status_to   at status : 4
var volatile bit  status_rp0  at status : 5
var volatile bit  status_rp1  at status : 6
var volatile bit  status_irp  at status : 7

var volatile bit  intcon_gie  at intcon : 7
var volatile bit  intcon_eeie at intcon : 6
var volatile bit  intcon_peie at intcon : 6
var volatile bit  intcon_t0ie at intcon : 5
var volatile bit  intcon_inte at intcon : 4
var volatile bit  intcon_rbie at intcon : 3
var volatile bit  intcon_t0if at intcon : 2
var volatile bit  intcon_intf at intcon : 1
var volatile bit  intcon_rbif at intcon : 0

var volatile bit  ccp1x at f877_ccp1con : 5
var volatile bit  ccp1y at f877_ccp1con : 4

var volatile bit  adcon0_go     at f877_adcon0 : 2
var volatile bit  adcon0_ch0    at f877_adcon0 : 3
var volatile bit  adcon0_ch1    at f877_adcon0 : 4
var volatile bit  adcon0_ch2    at f877_adcon0 : 5
var volatile bit  eecon1_rd     at f877_eecon1 : 0
var volatile bit  eecon1_wr     at f877_eecon1 : 1
var volatile bit  eecon1_wren   at f877_eecon1 : 2
var volatile bit  eecon1_wrerr  at f877_eecon1 : 3
var volatile bit  eecon1_eepgd  at f877_eecon1 : 7

-- --------------------------------------------------------------------
-- register bank selection
-- --------------------------------------------------------------------

procedure bank_0 is
   if( target_chip == pic_16f877 ) then
      asm bcf status, 5
      asm bcf status, 6
   end if
   asm bank 0
end procedure

procedure bank_1 is
   if( target_chip == pic_16f877 ) then
      asm bsf status, 5
      asm bcf status, 6
   end if
   asm bank 1
end procedure

procedure bank_2 is
   if( target_chip == pic_16f877 ) then
      asm bcf status, 5
      asm bsf status, 6
   end if
   asm bank 2
end procedure

procedure bank_3 is
   if( target_chip == pic_16f877 ) then
      asm bsf status, 5
      asm bsf status, 6
   end if
   asm bank 3
end procedure

procedure bank_4 is
   asm bank 4
end procedure

procedure bank_5 is
   asm bank 5
end procedure

procedure bank_6 is
   asm bank 6
end procedure

procedure bank_7 is
   asm bank 7
end procedure

-- --------------------------------------------------------------------
-- option put and get
-- --------------------------------------------------------------------

procedure option'put( byte in x ) is
   assembler
      bank  movfw x
            option
   end assembler
end procedure

function option'get return byte is
   var byte x
   asm bank movfw 0x81
   if( target_chip == pic_16f877 ) then bank_1 end if
   asm bank  movwf x
   if( target_chip == pic_16f877 ) then bank_0 end if
   return x
end function

-- --------------------------------------------------------------------
-- port and pin direction
-- --------------------------------------------------------------------

const bit input           = on
const bit output          = off
const byte all_input      = 0b_1111_1111
const byte all_output     = 0b_0000_0000

-- shadows of the actual tris values
var byte trisa
var byte trisb
var byte trisc
var byte trisd
var byte trise

-- Bring the applicable trisX values in accordance
-- with the power-on hardware defaults.
trisa = all_input
if target_cpu != pic_12 then
   trisb = all_input
end if
if target_chip == pic_16f877 | target_cpu == sx_12 then
   trisc = all_input
end if
if target_chip == pic_16f877 then
   trisd = all_input
   trise = 0x0F -- high nibble has other functions!
end if

procedure _trisa_flush is
   assembler
      bank movfw trisa
           tris  5
   end assembler
end procedure

procedure _trisb_flush is
   assembler
      bank movfw trisb
           tris  6
   end assembler
end procedure

procedure _trisc_flush is
   assembler
      bank movfw trisc
           tris  7
   end assembler
end procedure

procedure _trisd_flush is
   asm movfw trisd
   bank_1
   asm movwf 0x8
   bank_0
end procedure

procedure _trise_flush is
   asm movfw trise
   bank_1
   asm movwf 0x9
   bank_0
end procedure

var byte port_a_direction at trisa
procedure port_a_direction'put( byte in x at trisa ) is
   _trisa_flush
end procedure

var byte port_b_direction at trisb
procedure port_b_direction'put( byte in x at trisb ) is
   _trisb_flush
end procedure

var byte port_c_direction at trisc
procedure port_c_direction'put( byte in x at trisc ) is
   _trisc_flush
end procedure

var byte port_d_direction at trisd
procedure port_d_direction'put( byte in x at trisd ) is
   _trisd_flush
end procedure

var byte port_e_direction at trise
procedure port_e_direction'put( byte in x ) is
   var byte c at trise = ( trise & 0xF0 ) | ( x & 0x0F )
   _trise_flush
end procedure

var bit pin_a0_direction at trisa : 0
var bit pin_a1_direction at trisa : 1
var bit pin_a2_direction at trisa : 2
var bit pin_a3_direction at trisa : 3
var bit pin_a4_direction at trisa : 4
var bit pin_a5_direction at trisa : 5

procedure pin_a0_direction'put( bit in d at trisa : 0 ) is
   _trisa_flush
end procedure
procedure pin_a1_direction'put( bit in d at trisa : 1 ) is
   _trisa_flush
end procedure
procedure pin_a2_direction'put( bit in d at trisa : 2 ) is
   _trisa_flush
end procedure
procedure pin_a3_direction'put( bit in d at trisa : 3 ) is
   _trisa_flush
end procedure
procedure pin_a4_direction'put( bit in d at trisa : 4 ) is
   _trisa_flush
end procedure

var bit pin_b0_direction at trisb : 0
var bit pin_b1_direction at trisb : 1
var bit pin_b2_direction at trisb : 2
var bit pin_b3_direction at trisb : 3
var bit pin_b4_direction at trisb : 4
var bit pin_b5_direction at trisb : 5
var bit pin_b6_direction at trisb : 6
var bit pin_b7_direction at trisb : 7

procedure pin_b0_direction'put( bit in d at trisb : 0 ) is
   _trisb_flush
end procedure
procedure pin_b1_direction'put( bit in d at trisb : 1 ) is
   _trisb_flush
end procedure
procedure pin_b2_direction'put( bit in d at trisb : 2 ) is
   _trisb_flush
end procedure
procedure pin_b3_direction'put( bit in d at trisb : 3 ) is
   _trisb_flush
end procedure
procedure pin_b4_direction'put( bit in d at trisb : 4 ) is
   _trisb_flush
end procedure
procedure pin_b5_direction'put( bit in d at trisb : 5 ) is
   _trisb_flush
end procedure
procedure pin_b6_direction'put( bit in d at trisb : 6 ) is
   _trisb_flush
end procedure
procedure pin_b7_direction'put( bit in d at trisb : 7 ) is
   _trisb_flush
end procedure

var bit pin_c0_direction at trisc : 0
var bit pin_c1_direction at trisc : 1
var bit pin_c2_direction at trisc : 2
var bit pin_c3_direction at trisc : 3
var bit pin_c4_direction at trisc : 4
var bit pin_c5_direction at trisc : 5
var bit pin_c6_direction at trisc : 6
var bit pin_c7_direction at trisc : 7

procedure pin_c0_direction'put( bit in d at trisc : 0 ) is
   _trisc_flush
end procedure
procedure pin_c1_direction'put( bit in d at trisc : 1 ) is
   _trisc_flush
end procedure
procedure pin_c2_direction'put( bit in d at trisc : 2 ) is
   _trisc_flush
end procedure
procedure pin_c3_direction'put( bit in d at trisc : 3 ) is
   _trisc_flush
end procedure
procedure pin_c4_direction'put( bit in d at trisc : 4 ) is
   _trisc_flush
end procedure
procedure pin_c5_direction'put( bit in d at trisc : 5 ) is
   _trisc_flush
end procedure
procedure pin_c6_direction'put( bit in d at trisc : 6 ) is
   _trisc_flush
end procedure
procedure pin_c7_direction'put( bit in d at trisc : 7 ) is
   _trisc_flush
end procedure

var bit pin_d0_direction at trisd : 0
var bit pin_d1_direction at trisd : 1
var bit pin_d2_direction at trisd : 2
var bit pin_d3_direction at trisd : 3
var bit pin_d4_direction at trisd : 4
var bit pin_d5_direction at trisd : 5
var bit pin_d6_direction at trisd : 6
var bit pin_d7_direction at trisd : 7

procedure pin_d0_direction'put( bit in d at trisd : 0 ) is
   _trisd_flush
end procedure
procedure pin_d1_direction'put( bit in d at trisd : 1 ) is
   _trisd_flush
end procedure
procedure pin_d2_direction'put( bit in d at trisd : 2 ) is
   _trisd_flush
end procedure
procedure pin_d3_direction'put( bit in d at trisd : 3 ) is
   _trisd_flush
end procedure
procedure pin_d4_direction'put( bit in d at trisd : 4 ) is
   _trisd_flush
end procedure
procedure pin_d5_direction'put( bit in d at trisd : 5 ) is
   _trisd_flush
end procedure
procedure pin_d6_direction'put( bit in d at trisd : 6 ) is
   _trisd_flush
end procedure
procedure pin_d7_direction'put( bit in d at trisd : 7 ) is
   _trisd_flush
end procedure

var bit pin_e0_direction at trisc : 0
var bit pin_e1_direction at trisc : 1
var bit pin_e2_direction at trisc : 2

procedure pin_e0_direction'put( bit in d at trise : 0 ) is
   _trise_flush
end procedure
procedure pin_e1_direction'put( bit in d at trise : 1 ) is
   _trise_flush
end procedure
procedure pin_e2_direction'put( bit in d at trise : 2 ) is
   _trise_flush
end procedure

procedure port_a_low_direction'put( byte in d ) is
   var byte a at trisa = ( trisa & 0xF0 ) | ( d & 0x0F )
   _trisa_flush
end procedure
procedure port_a_high_direction'put( byte in d ) is
   var byte a at trisa = ( trisa & 0x0F ) | ( ( d & 0x0F ) << 4 )
   _trisa_flush
end procedure

procedure port_b_low_direction'put( byte in d ) is
   var byte b at trisb = ( trisb & 0xF0 ) | ( d & 0x0F )
   _trisb_flush
end procedure
procedure port_b_high_direction'put( byte in d ) is
   var byte b at trisb  = ( trisb & 0x0F ) | ( ( d & 0x0F ) << 4 )
   _trisb_flush
end procedure

procedure port_c_low_direction'put( byte in d ) is
   var byte c at trisc = ( trisc & 0xF0 ) | ( d & 0x0F )
   _trisc_flush
end procedure
procedure port_c_high_direction'put( byte in d ) is
   var byte c at trisc = ( trisc & 0x0F ) | ( ( d & 0x0F ) << 4 )
   _trisc_flush
end procedure

procedure port_d_low_direction'put( byte in d ) is
   var byte c at trisd = ( trisd & 0xF0 ) | ( d & 0x0F )
   _trisd_flush
end procedure
procedure port_d_high_direction'put( byte in d ) is
   var byte c at trisd = ( trisd & 0x0F ) | ( ( d & 0x0F ) << 4 )
   _trisd_flush
end procedure

procedure port_e_low_direction'put( byte in d ) is
   var byte c at trise = ( trise & 0xF0 ) | ( d & 0x0F )
   _trise_flush
end procedure

function port_a_low_direction'get return byte is
   var byte a at trisa
   return a & 0x0F
end function
function port_a_high_direction'get return byte is
   var byte a at trisa
   return a >> 4
end function

function port_b_low_direction'get return byte is
   var byte b at trisb
   return b & 0x0F
end function
function port_b_high_direction'get return byte is
   var byte b at trisb
   return b >> 4
end function

function port_c_low_direction'get return byte is
   var byte b at trisc
   return b & 0x0F
end function
function port_c_high_direction'get return byte is
   var byte b at trisc
   return b >> 4
end function

function port_d_low_direction'get return byte is
   var byte b at trisd
   return b & 0x0F
end function
function port_d_high_direction'get return byte is
   var byte b at trisd
   return b >> 4
end function

function port_e_low_direction'get return byte is
   var byte b at trise
   return b & 0x0F
end function

-- port and pin value

var byte _port_a_buffer
var byte _port_b_buffer
var byte _port_c_buffer
var byte _port_d_buffer
var byte _port_e_buffer

procedure _port_a_flush is
   var volatile byte port_a at 5 = _port_a_buffer
end procedure
procedure _port_b_flush is
   var volatile byte port_b at 6 = _port_b_buffer
end procedure
procedure _port_c_flush is
   var volatile byte port_c at 7 = _port_c_buffer
end procedure
procedure _port_d_flush is
   var volatile byte port_d at 8 = _port_d_buffer
end procedure
procedure _port_e_flush is
   var volatile byte port_e at 9 = _port_e_buffer
end procedure

procedure port_a'put( byte in x at _port_a_buffer ) is
   _port_a_flush
end procedure
procedure port_b'put( byte in x at _port_b_buffer ) is
   _port_b_flush
end procedure
procedure port_c'put( byte in x at _port_c_buffer ) is
   _port_c_flush
end procedure
procedure port_d'put( byte in x at _port_d_buffer ) is
   _port_d_flush
end procedure
procedure port_e'put( byte in x at _port_e_buffer ) is
   _port_e_flush
end procedure

procedure port_a_low'put( byte in x ) is
   _port_a_buffer = ( _port_a_buffer  & 0xF0 ) | ( x & 0x0F )
   _port_a_flush
end procedure
function port_a_low'get return byte is
   return _port_a_buffer & 0x0F
end function

procedure port_b_low'put( byte in x ) is
   _port_b_buffer = ( _port_b_buffer  & 0xF0 ) | ( x & 0x0F )
   _port_b_flush
end procedure
function port_b_low'get return byte is
   return _port_b_buffer & 0x0F
end function

procedure port_b_high'put( byte in x ) is
   _port_b_buffer = ( _port_b_buffer & 0x0F ) | ( x << 4 )
   _port_b_flush
end procedure
function port_b_high'get return byte is
   return _port_b_buffer >> 4
end function

procedure port_c_low'put( byte in x ) is
   _port_c_buffer = ( _port_c_buffer  & 0xF0 ) | ( x & 0x0F )
   _port_c_flush
end procedure
function port_c_low'get return byte is
   return _port_c_buffer & 0x0F
end function

procedure port_c_high'put( byte in x ) is
   _port_c_buffer = ( _port_c_buffer & 0x0F ) | ( x << 4 )
   _port_c_flush
end procedure
function port_c_high'get return byte is
   return _port_c_buffer >> 4
end function

procedure port_d_low'put( byte in x ) is
   _port_d_buffer = ( _port_d_buffer  & 0xF0 ) | ( x & 0x0F )
   _port_d_flush
end procedure
function port_d_low'get return byte is
   return _port_d_buffer & 0x0F
end function

procedure port_d_high'put( byte in x ) is
   _port_d_buffer = ( _port_d_buffer & 0x0F ) | ( x << 4 )
   _port_d_flush
end procedure
function port_d_high'get return byte is
   return _port_d_buffer >> 4
end function

procedure port_e_low'put( byte in x ) is
   _port_e_buffer = ( _port_e_buffer  & 0xF0 ) | ( x & 0x0F )
   _port_e_flush
end procedure
function port_e_low'get return byte is
   return _port_e_buffer & 0x0F
end function

procedure pin_a0'put( bit in x at _port_a_buffer : 0 ) is
   _port_a_flush
end procedure
procedure pin_a1'put( bit in x at _port_a_buffer : 1 ) is
   _port_a_flush
end procedure
procedure pin_a2'put( bit in x at _port_a_buffer : 2 ) is
   _port_a_flush
end procedure
procedure pin_a3'put( bit in x at _port_a_buffer : 3 ) is
   _port_a_flush
end procedure
procedure pin_a4'put( bit in x at _port_a_buffer : 4 ) is
   _port_a_flush
end procedure
procedure pin_a5'put( bit in x at _port_a_buffer : 5 ) is
   _port_a_flush
end procedure

procedure pin_b0'put( bit in x at _port_b_buffer : 0 ) is
   _port_b_flush
end procedure
procedure pin_b1'put( bit in x at _port_b_buffer : 1 ) is
   _port_b_flush
end procedure
procedure pin_b2'put( bit in x at _port_b_buffer : 2 ) is
   _port_b_flush
end procedure
procedure pin_b3'put( bit in x at _port_b_buffer : 3 ) is
  _port_b_flush
end procedure
procedure pin_b4'put( bit in x at _port_b_buffer : 4 ) is
   _port_b_flush
end procedure
procedure pin_b5'put( bit in x at _port_b_buffer : 5 ) is
   _port_b_flush
end procedure
procedure pin_b6'put( bit in x at _port_b_buffer : 6 ) is
   _port_b_flush
end procedure
procedure pin_b7'put( bit in x at _port_b_buffer : 7 ) is
   _port_b_flush
end procedure

procedure pin_c0'put( bit in x at _port_c_buffer : 0 ) is
   _port_c_flush
end procedure
procedure pin_c1'put( bit in x at _port_c_buffer : 1 ) is
   _port_c_flush
end procedure
procedure pin_c2'put( bit in x at _port_c_buffer : 2 ) is
   _port_c_flush
end procedure
procedure pin_c3'put( bit in x at _port_c_buffer : 3 ) is
   _port_c_flush
end procedure
procedure pin_c4'put( bit in x at _port_c_buffer : 4 ) is
   _port_c_flush
end procedure
procedure pin_c5'put( bit in x at _port_c_buffer : 5 ) is
   _port_c_flush
end procedure
procedure pin_c6'put( bit in x at _port_c_buffer : 6 ) is
   _port_c_flush
end procedure
procedure pin_c7'put( bit in x at _port_c_buffer : 7 ) is
   _port_c_flush
end procedure

procedure pin_d0'put( bit in x at _port_d_buffer : 0 ) is
   _port_d_flush
end procedure
procedure pin_d1'put( bit in x at _port_d_buffer : 1 ) is
   _port_d_flush
end procedure
procedure pin_d2'put( bit in x at _port_d_buffer : 2 ) is
   _port_d_flush
end procedure
procedure pin_d3'put( bit in x at _port_d_buffer : 3 ) is
   _port_d_flush
end procedure
procedure pin_d4'put( bit in x at _port_d_buffer : 4 ) is
   _port_d_flush
end procedure
procedure pin_d5'put( bit in x at _port_d_buffer : 5 ) is
   _port_d_flush
end procedure
procedure pin_d6'put( bit in x at _port_d_buffer : 6 ) is
   _port_d_flush
end procedure
procedure pin_d7'put( bit in x at _port_d_buffer : 7 ) is
   _port_d_flush
end procedure

procedure pin_e0'put( bit in x at _port_e_buffer : 0 ) is
   _port_e_flush
end procedure
procedure pin_e1'put( bit in x at _port_e_buffer : 1 ) is
   _port_e_flush
end procedure
procedure pin_e2'put( bit in x at _port_e_buffer : 2 ) is
   _port_e_flush
end procedure


-- --------------------------------------------------------------------
-- indirect access to the file registers
-- --------------------------------------------------------------------

procedure file_get( byte in a, byte out d ) is begin
   if target_cpu != pic_14 then
      pragma error -- not implemented yet
   end if
   fsr = a
   d   = indf
end procedure

procedure file_put( byte in a, byte in d ) is begin
   if target_cpu != pic_14 then
      pragma error -- not implemented yet
   end if
   fsr  = a
   indf = d
end procedure


-- --------------------------------------------------------------------
-- (indirect) access to the eeprom
-- original versions corrected by AxelK
-- --------------------------------------------------------------------

procedure eeprom_get( byte in a, byte out d ) is

   if ( target_chip == pic_16c84 ) | ( target_chip == pic_16f84 ) then

      var volatile bit ee_read at 8 : 0

      x84_eeadr        = a
      status_rp0       = on          -- select page 1
      ee_read          = on          -- set read bit in EECON1
      status_rp0       = off         -- back to page 0
      d                = x84_eedata  -- the actual data from eeprom

   elsif target_chip == pic_16f877 then

      f877_eeadr   = a

      -- 16F877 datasheet p45
      assembler
         bank bcf eecon1_eepgd
              bsf eecon1_rd
      end assembler

      a            = f877_eedata

   else
      pragma error -- eeprom not available
   end if
end procedure

procedure eeprom_put( byte in a, byte in d ) is

   if ( target_chip == pic_16c84 ) | ( target_chip == pic_16f84 ) then

      var volatile bit ee_write        at 8 : 1
      var volatile bit ee_write_enable at 8 : 2

      -- preparation
      x84_eeadr        = a
      x84_eedata       = d

      status_rp0       = on      -- select page 1
      ee_write_enable  = on
      x84_eeadr        = 0x55    -- to EECON2
      x84_eeadr        = 0xAA    -- to EECON2
      ee_write         = on

      -- wait for completion
      while ee_write loop end loop

      ee_write_enable = off      -- disable writing to prevent accidental writes
      status_rp0      = off      -- back to page 0

   elsif target_chip == pic_16f877 then

      f877_eeadr   = a
      f877_eedata  = d

      -- 16F877 datasheet p45
      assembler
         bank bcf eecon1_eepgd
         bank bsf eecon1_wren
         bank bcf intcon_gie
              movlw 0x55
         bank movwf f877_eecon2
              movlw 0xAA
         bank movwf f877_eecon2
         bank bsf eecon1_wr
         bank bsf intcon_gie
              sleep
         bank bcf eecon1_wren
      end assembler

   else
      pragma error -- eeprom not available
   end if
end procedure

-- --------------------------------------------------------------------
-- (indirect) access to the code flash
-- --------------------------------------------------------------------

procedure flash_get(
   byte in  al,
   byte in  ah,
   byte out dl,
   byte out dh
) is
   if ( target_chip != pic_16f877 ) then
      pragma error -- flash read/write not available
   end if

   f877_eeadrh = ah
   f877_eeadr  = al

   -- 16F877 datasheet p44
   assembler
      bank bsf status_rp0
      bank bsf status_rp1
      bank bsf eecon1_eepgd
      bank bsf eecon1_rd
           nop
           nop
   end assembler

   dl = f877_eedata
   dh = f877_eedath

end procedure

procedure flash_put(
   byte in al,
   byte in ah,
   byte in dl,
   byte in dh
) is
   if ( target_chip != pic_16f877 ) then
      pragma error -- flash read/write not available
   end if

   f877_eeadrh = ah
   f877_eeadr  = al
   dl = f877_eedata
   dh = f877_eedath

   -- 16F877 datasheet p45
   assembler
      bank bsf status_rp0
      bank bsf status_rp1
      bank bsf eecon1_eepgd
      bank bsf eecon1_wren
      bank bcf intcon_gie
           movlw 0x55
      bank movwf f877_eecon2
           movlw 0xAA
      bank movwf f877_eecon2
      bank bsf eecon1_wr
           nop
           nop
      bank bsf intcon_gie
      bank bcf eecon1_wren
   end assembler

end procedure

-- --------------------------------------------------------------------
-- pic special functions
-- --------------------------------------------------------------------

procedure sleep is
   asm sleep
end procedure

procedure clear_watchdog is
   asm clrwdt
end procedure

procedure swap_nibbles( byte in out x ) is
   asm bank swapf x, f
end procedure

-- disable the f877 A/D to be able to use port a as input
procedure disable_a_d_functions is
 bank_1
 asm movlw 7
 asm movwf 0x1F
 bank_0
end procedure

Questions:

• plsangita at -Remove-yahoo.co.in asks: " What does EE_read function do?
  I will be highly oblized if anyone explain me the function in detail." +