Nim Hard Port Configuration Example

gpio_setup_example.nim

type
  Direction* = enum
    input
    output

  PinConf* = object
    dir: Direction 

  Port0* = object
    pin: array[32, PinConf]
  RefPort0* = ptr Port0

  Port1* = object
    pin: array[32, PinConf]
  RefPort1* = ptr Port1

var
  # a real microcontroller would need a bit of magic here
  # to ensure the correct memory addresses were used
  port0 = Port0()
  port1 = Port1()

  # normally just import these from the C headers as-is
  # but this lets us run it
  p0* : RefPort0 = addr port0
  p1* : RefPort1 = addr port1

var rows = (
     ( port: p1, pin: 0 ),
     ( port: p1, pin: 1 ),
     ( port: p1, pin: 2 ),
     ( port: p1, pin: 4 ),
  )

var cols = (
    (port: p0, pin: 13 ),
    (port: p1, pin: 15 ),
    (port: p0, pin: 17 ),
    (port: p0, pin: 20 ),
    (port: p0, pin: 22 ),
    (port: p0, pin: 24 ),
    (port: p0, pin: 9 ),
    (port: p0, pin: 10 ),
    (port: p0, pin: 4 ),
    (port: p0, pin: 26 ),
    (port: p0, pin: 2 )
  )

proc initKeyboardGPIO() =
  rows[0].port.pin[rows[0].pin].dir = output

  for item in rows.fields: 
    item.port.pin[item.pin].dir = output

  for item in cols.fields: 
    var port = item.port
    port.pin[item.pin].dir = output

echo "\nPre"
echo "pre init: p0: " & $p0[]
echo "pre init: p1: " & $p1[]

echo "\nSetup"
initKeyboardGPIO()

echo "\nPost"
echo "post init: p0: " & $p0[]
echo "post init: p1: " & $p1[]

Compile and run:

time nim c -r gpio_setup_example.nim

Pre
pre init: p0: (pin: [(dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input)])
pre init: p1: (pin: [(dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input)])

Setup

Post
post init: p0: (pin: [(dir: input), (dir: input), (dir: output), (dir: input), (dir: output), (dir: input), (dir: input), (dir: input), (dir: input), (dir: output), (dir: output), (dir: input), (dir: input), (dir: output), (dir: input), (dir: input), (dir: input), (dir: output), (dir: input), (dir: input), (dir: output), (dir: input), (dir: output), (dir: input), (dir: output), (dir: input), (dir: output), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input)])
post init: p1: (pin: [(dir: output), (dir: output), (dir: output), (dir: input), (dir: output), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: output), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input), (dir: input)])
nim c -r gpio_setup.nim  0.42s user 0.21s system 103% cpu 0.610 total