/prog/ - Is my Lisp enterprise enough?

Name: Anonymous 2012-03-11 11:56



(defun png-load-stream (bs)

    (let* ((chunks (png-parse bs))

           (g nil)

           (chns 0)

           (IHDR (gethash "IHDR" chunks))

           (IDAT (gethash "IDAT" chunks))

           (PLTE (gethash "PLTE" chunks)))

      (unless IHDR (gfx-load-error "Missing IHDR"))

      (unless IDAT (gfx-load-error "Missing IDAT"))

      (deser (strm IHDR) ((width     msb 4)

                          (height    msb 4)

                          (chn-depth msb 1)

                          (type      msb 1)

                          (enc       msb 1)

                          (filter    msb 1)

                          (interlace msb 1))

        (unless (= enc 0) (gfx-load-error "Unsupported encoding (~a)" enc))

        (setf chns (case type

                     (0 1) ; grayscale

                     (2 3) ; truecolor

                     (3 2) ; indexed

                     (4 4) ; grayscale with alpha

                     (6 4) ; truecolor with alpha

                     (otherwise (gfx-load-error "Invalid color type (~d)" type))))

        (setf g (gfx width height :c chns))

        (setf IDAT (zlib-unpack-bytes IDAT))

        (png-defilter g IDAT)

        (case interlace

          (0 ) ; no interlace

          (1 (gfx-load-error "Interlaced PNGs are not supported")) (png-deinterlace-adam7 g))

          (otherwise (gfx-load-error "Invalid interlace type (~d)" type)))

        (when PLTE

          (let ((a (vec 256 u4))

                (n (truncate (length PLTE) 3))

                (s (strm PLTE)))

            (dotimes (i n)

              (deser s ((r msb 1)

                        (g msb 1)

                        (b msb 1))

                (setf (aref a i) (rgb r g b))))

            (setf (gfx-m g) a)))

        g))))

Name: Anonymous 2012-03-11 12:06

>>1
Cool, although error handling can likely be done better by using conditions, but only if those errors can actually be recovered from.

Name: Anonymous 2012-03-11 13:32

looks nice, how fast is it?

Name: Anonymous 2012-03-11 13:51

>>3
Doesn't your monkey ass know how to benchmark code?

Name: Anonymous 2012-03-11 13:58

>>4
There's no way >>3 would be able to do it, even if he knew how, simply because you only provided one function and didn't include the other functions or macros.

Name: Anonymous 2012-03-11 13:59

Your parens are dead. Like Batman's.

Actually they're just unbalanced.

Name: Anonymous 2012-03-11 14:10

Too bad Lisp is shit.

Name: Anonymous 2012-03-11 14:12

>>7

translation: i am incapable of understanding the power of lisp

Name: Anonymous 2012-03-11 14:50

>>6
That is because I write my code in Microsoft Notepad.

Name: Anonymous 2012-03-11 14:55

>>9
I'm surprised you manage to keep everything indented properly - CL indentation rules are quite fancy, but nobody has problems with this because the editors do it for you, but having to do it by yourself sounds like a bit of effort.

Name: Anonymous 2012-03-11 16:07

Here is how I do "pointer arithmetics":



(defmacro inc (p &rest n)

  (setf n (or (car n) 1))

  `(prog1 (aref (car ,p) (the fixnum (cdr ,p)))

     (setf (cdr ,p) (the fixnum (+ (cdr ,p) ,n)))))



(let ((p (cons #(6 1 2 3) 0)))

  (list (inc p) (inc p) p))

Is my Lisp enterprise enough?

1 Name: Anonymous 2012-03-11 11:56

2 Name: Anonymous 2012-03-11 12:06

3 Name: Anonymous 2012-03-11 13:32

4 Name: Anonymous 2012-03-11 13:51

5 Name: Anonymous 2012-03-11 13:58

6 Name: Anonymous 2012-03-11 13:59

7 Name: Anonymous 2012-03-11 14:10

8 Name: Anonymous 2012-03-11 14:12

9 Name: Anonymous 2012-03-11 14:50

10 Name: Anonymous 2012-03-11 14:55

11 Name: Anonymous 2012-03-11 16:07