-- T_straight_chans macro 0.002: (C) A E Lawrence 1993,1994

-- #INCLUDE "harp1plc.inc" -- This declares XFPGA.w
[2]PORT OF INT FPGA.chan.ports:
PLACE FPGA.chan.ports AT XFPGA.w:
-- {{{ indices and masks
VAL INT flags.index IS 0:
-- VAL []INT from.FPGA.indices IS [1]:
-- VAL []INT to.FPGA.indices IS [0]:
-- VAL []INT from.bit.masks IS [1]:
-- VAL []INT to.bit.masks IS [2]:
-- }}}
PROTOCOL EVENT IS ANY: -- Toolset flavour
CHAN OF EVENT EventIn :  -- ANY EventIn | EVENT EventIn
PLACE EventIn AT 8 :
VAL no.of.channels IS 2:
-- {{{ ready channels between Event.Handler and clients
[no.of.channels]CHAN OF BOOL ready:

-- {{{ COMMENT Notes on abbreviations below
-- Possible abbreviations using FPGA internal names (`_' changed to `.')
-- are included. However, the abbreviations for the PORTS are commented out.
-- The reason is that otherwise the compiler may report an aliasing problem.
-- Any abbreviation of an array must be disjoint: this is to ensure that there
-- is a unique name for any port in any scope. In the current situation, a
-- single address really represents two ports, one in each direction.
-- 
-- The commented abbreviations may be used if they are moved into a local
-- scope, so that there is only one alias for a given port at any point
-- Or the compiler alias checking can be turned off temporarily.
-- It is preferable to use the abbreviations in outermost local scope:
-- with most compilers, this leads to more efficient code.
-- }}}
-- {{{ Channels FPGA ----> transputer
-- {{{ C.cout.0
ready.C.cout.0 IS ready[0] :
-- port.C.cout.0 IS FPGA.chan.ports[1] :
-- }}}
-- }}}
-- {{{ Channels transputer ----> FPGA
-- {{{ ChanOut.Bus.3
ready.ChanOut.Bus.3 IS ready[1] :
-- port.ChanOut.Bus.3 IS FPGA.chan.ports[0] :
-- }}}
-- }}}
-- }}}
-- {{{ Event.Handler, version 1
-- Version 1: Fast, but termination might be awkward in rare circumstances
-- active in Event.Handler below must be FPGA.chan.ports[flags.index]
-- or an alias defined with an abbreviation.

-- {{{ Event.Handler
-- Advantages: fewest branches in ALT, and this reduces if any channels
-- shut down early. Disadvantage: termination might be awkward in rare
-- circumstances

--  There is scope for improved efficiency below, including:-
--   1) moving 1 << i out of the replicated ALT;  and
--   2) avoiding indexing into ready in the replicated ALT.
--  This is automatically generated code, and you may wish to
--  use an ALT with explicit rather than replicated branches.
--  However, the largest overhead is servicing the Event channel.

-- {{{ Event.Handler
PROC Event.Handler(PORT OF INT active,[no.of.channels]CHAN OF BOOL ready)
  -- {{{ COMMENT CSP (FDRish)
  --  A, "Alive", is the set of channels active, as seen from the transputer
  --  H, "Hready", is the set of hardware channels both alive *and* ready.
  --  Thus   Hready - Alive = {}  is always true.
  -- 
  --  Event.handler = Ev.hand({},0..n-1)
  --  Ev.hand(H,{}) = SKIP
  --  Ev.hand(H,A) = ready(H,A) [] event(H,A)
  -- 
  --  ready(H,A) = [] i:A @ ( ready.i ? more ->
  --                   ( if more then Ev.hand(H-{i},A)
  --                        else Ev.hand(H-{i},A-{i}) ) )
  -- 
  --  event(H,A) = event ? flags -> Ev.hand( (H union flags) intersect A, A)
  -- }}}
  VAL flag.mask IS (1 << no.of.channels) MINUS 1 :
  BOOL any,talking :
  INT flags,Hready,alive :
  SEQ
    Hready,alive := 0,flag.mask
    -- {{{ main loop
    WHILE alive <> 0
      PRI ALT
        -- {{{ Any ready
        ALT i = 0 FOR no.of.channels
          VAL bit.mask IS 1 << i :  -- move out for more speed
          ((Hready /\ bit.mask) <> 0) & ready[i] ? talking
            SEQ
              -- {{{ turn off hardware reflection
              Hready := Hready /\ (~bit.mask)
              -- }}}
              IF
                -- {{{ more
                talking
                  SKIP
                -- }}}
                -- {{{ otherwise deactivate this channel
                TRUE
                  alive := alive /\ (~bit.mask)
                -- }}}
        -- }}}
        -- {{{ Event?  (This may be very frequent, so lower priority)
        EventIn ? flags
          SEQ
            active ? flags
            flags := flags /\ alive    -- ignore any channels shut down
            Hready := Hready \/ flags
        -- }}}
    -- }}}
:
-- }}}
-- }}}
-- }}}

-- There may be further occam components below from embedded sub-macros.
-- These can probably be ignored and should be deleted:-
-- {{{ TP_bd & TP_bdl macros: (C) A E Lawrence 1994
-- {{{ Toolset version
-- #COMMENT T_bd macro: (C) A E Lawrence 1994
-- #INCLUDE "harp1plc.inc" -- This declares XFPGA.array as below
-- [#400000]INT XFPGA.array :    -- allows block move (2^27 words) on array
-- PLACE XFPGA.array AT XFPGA.w :

-- {{{ COMMENT PORT alternative
-- [#400000]PORT OF INT XFPGA : -- This is normally mutually exclusive with
-- PLACE XFPGA AT XFPGA.w :     --  XFPGA.array. For both, use RETYPE...
-- }}}
-- }}}
-- }}}