-- (c) William Welch 2004
--
-- This software is provided 'as-is', without any express or implied 
-- warranty. In no event will the authors be held liable for any damages 
-- arising from the use of this software.
--
-- Permission is granted to anyone to use this software for any purpose, 
-- including commercial applications, and to alter it and redistribute it 
-- freely, subject to the following restrictions:
--
-- 1. The origin of this software must not be misrepresented; 
--    you must not claim that you wrote the original software. 
--    If you use this software in a product, an acknowledgment in 
--    the product documentation would be appreciated but is not required.
--
-- 2. Altered source versions must be plainly marked as such, and must 
--    not be misrepresented as being the original software.
--
-- 3. This notice may not be removed or altered from any source distribution.
--
-- This license is commonly known as the zlib/libpng License.
--
-- whack452.jal 27 may 2005
-- This is for a 18F452 connected to a EDTP PacketWhacker card
--
-- FIXME -- double check all of these fuses !!!
pragma target fuses       0x00,  0
pragma target fuses       0x01,  0b_00_1_00_010   -- no switching, HS, no PLL
pragma target fuses       0x02,  0b_0000_11_1_0   -- Vbor=2.0, bor, PWRT
pragma target fuses       0x03,  0b_0000_111_0    -- no wdt
pragma target fuses       0x04,  0
pragma target fuses       0x05,  0
pragma target fuses       0x06,  0b_1_0000_0_0_0  -- no debug, no LVP, no stov reset
pragma target fuses       0x07,  0
pragma target fuses       0x08,  0b_1111_0000     -- no code readout protection
pragma target fuses       0x09,  0b_11_000000     -- no data readout protection
pragma target fuses       0x0A,  0b_0000_1111     -- no code self-write protection
pragma target fuses       0x0B,  0b_111_00000     -- no various write protections
pragma target fuses       0x0C,  0b_0000_1111     -- no table read protection
pragma target fuses       0x0D,  0b_0_1_000000    -- no boot block read protection
pragma target fuses       0x0E,  0
pragma target fuses       0x0F,  0

-- picmicro i/o port and i/o pin assignments.
-- The original NE2000 card was plugged into the "ISA" bus on the PC. And some of the chips
-- that claim to be "NE2000 compatible" used the "ISA" bus naming conventions.
-- So that is why I using these names for the I/O pins.

-- ISA address bus, low 5 bits
port_b_direction  = all_output 
var byte isa_addr is portb

-- ISA 8 bit data bus
port_d_direction  = all_output 
var byte isa_data_direction is port_d_direction, isa_data is portd
isa_data = 0

-- ISA read and write strobes. Both are active low signals
var bit isa_ior is pin_e0, isa_iow is pin_e1
isa_ior = high
isa_iow = high

-- ISA reset signal. Active high.
var bit isa_reset is pin_e2
port_e_low_direction = 0
isa_reset = low

-- one-time init of the system
procedure init_board is
  ADCON1 = 0b_0000_0110
  TRISA = 0
  LATA = 0xff
end procedure

-- debugging LED, not essential
procedure toggle_led is
  LATA = LATA ^ 1;
end procedure

procedure isa_write ( byte in addr, byte in v ) is
  isa_addr = addr & 0x1F      -- only 5 lower bytes active 
  isa_data = v
  isa_data_direction = all_output
  isa_iow = low
  isa_iow = high
  isa_data_direction = all_input
end procedure

function isa_read ( byte in addr ) return byte is
  var byte v
  isa_data_direction = all_input
  isa_addr = addr & 0x1F         -- only 5 lower bytes active 
  isa_ior = low
  v = isa_data
  isa_ior = high
  return v
end function