3DICC / SqueakNim

# We exercise some trivial types and how they map.
#
#   SqueakFFI      Nim
#   =========      ======
#   long       =>  int
#   char*      =>  cstring        

import math

# A single proc, returns an int. Since we are on 32 bits
# an int is 4 bytes (same size as pointer) and in Squeak FFI
# this is a long. The exportc pragma ensures that the exported
# name for this proc is exactly "hello" and not mangled.
proc hello*(): int {.exportc.} =
  42

# Trivial, a Nim string can be sent as a cstring because they are
# automatically 0-terminated.
proc foo*(): cstring {.exportc.} =
  "hey"

# Not a problem taking int arguments, they are "long" in Squeak FFI.
proc add*(x, y:int): int {.exportc.} =
  x + y

# Just return the length of a cstring
proc length*(x: cstring): int {.exportc.} =
  len(x)

# Here we convert cstrings to Nim strings, concatenate and return.
proc concat*(x, y: cstring): cstring {.exportc.} =
  $x & $y