honeylisp/editor/tiledraw/iigs.fnl

(local {: putpixel : make-canvas} (require :editor.tiledraw))

; converted from http://pixeljoint.com/forum/forum_posts.asp?TID=12795 (db16)
; maybe check out https://lospec.com/palette-list ?
(local pal [[1 0 1]  [4 2 3]  [3 3 6]  [4 4 4]  [8 4 3]   [3 6 2]   [13 4 4]  [7 7 6]
            [5 7 12] [13 7 2] [8 9 10] [6 10 2] [13 10 9] [6 12 12] [13 13 5] [13 14 13]])
(fn gs-to-rgb [color] (icollect [_ v (ipairs color)] (* v 0x11)))

(fn tile-to-sprite [tile]
  (if tile (make-canvas 16 16 (fn [canvas]
    (love.graphics.clear 0 0 0 0)
    (for [y 0 15]
      (for [x 0 15]
        (let [ibyte (+ (* y 16) x 1)
              byte (string.byte (tile:sub ibyte ibyte))
              mask (bit.band (bit.rshift byte 4) 0xf)
              color (bit.band byte 0xf)
              rgb (if (= mask 0) (gs-to-rgb (. pal (+ color 1))) [255 0 255])]
          (when (= mask 0) (putpixel x y rgb)))))))))

{: tile-to-sprite : pal : gs-to-rgb}