path: root/transect/ex4.k2

## read a character from stdin, save it to a global, write it to stdout

# variables are always references
#   read their address with their names: x (can't write to their address)
#   read/write their contents with a lookup: *x
var x : char

fn main [
  call read 0/stdin, x, 1/size
  result/EAX <- call write 1/stdout, x, 1/size
  call exit, result/EAX
]

fn read fd : int, x : (address array byte), size : int [
  EBX <- copy fd
  ECX <- copy x
  EDX <- copy size
  EAX <- copy 3/read
  syscall
]

fn write fd : int, x : (address array byte), size : int [
  EBX <- copy fd
  ECX <- copy x
  EDX <- copy size
  EAX <- copy 4/write
  syscall
]

fn exit x : int [
  code/EBX <- copy x
  code/EAX <- copy 1/exit
  syscall
]