| 1 | ;;; The Computer Language Benchmarks Game
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| 2 | ;;; http://shootout.alioth.debian.org/
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| 3 | ;;
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| 4 | ;;; Derived from the Chicken Scheme variant by Anthony Borla
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| 5 | ;;; contributed by Matthew Flatt
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| 6 | ;;
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| 7 | ;; ... then ported back to CHICKEN by felix
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| 8 |
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| 9 |
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| 10 | (use extras)
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| 11 |
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| 12 |
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| 13 | (define +limit-sqr+ 4.0)
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| 14 | (define +iterations+ 50)
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| 15 |
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| 16 | ;; -------------------------------
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| 17 |
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| 18 | (: mandelbrot (fixnum fixnum fixnum float -> fixnum))
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| 19 |
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| 20 | (define (mandelbrot x y n ci)
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| 21 | (let ((cr (fp- (fp/ (fp* 2.0 (exact->inexact x)) (exact->inexact n)) 1.5)))
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| 22 | (let loop ((i 0) (zr 0.0) (zi 0.0))
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| 23 | (if (> i +iterations+)
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| 24 | 1
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| 25 | (cond
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| 26 | ((fp> (fp+ (fp* zr zr) (fp* zi zi)) +limit-sqr+) 0)
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| 27 | (else (loop (fx+ 1 i)
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| 28 | (fp+ (fp- (fp* zr zr) (fp* zi zi)) cr)
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| 29 | (fp+ (fp* 2.0 (fp* zr zi)) ci))))))))
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| 30 |
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| 31 | ;; -------------------------------
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| 32 |
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| 33 | (define (main n)
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| 34 | (let ((out (current-output-port)))
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| 35 | (fprintf out "P4\n~a ~a\n" n n)
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| 36 | (let loop-y ((y 0))
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| 37 | (when (fx< y n)
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| 38 | (let ((ci (fp- (fp/ (fp* 2.0 (exact->inexact y)) (exact->inexact n)) 1.0)))
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| 39 | (let loop-x ((x 0) (bitnum 0) (byteacc 0))
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| 40 | (if (fx< x n)
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| 41 | (let ((bitnum (fx+ 1 bitnum))
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| 42 | (byteacc (+ (fxshl byteacc 1)
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| 43 | (mandelbrot x y n ci))))
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| 44 | (cond
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| 45 | ((= bitnum 8)
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| 46 | (write-byte byteacc out)
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| 47 | (loop-x (fx+ 1 x) 0 0))
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| 48 | (else (loop-x (fx+ 1 x) bitnum byteacc))))
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| 49 | (begin
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| 50 | (when (positive? bitnum)
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| 51 | (write-byte (fxshl byteacc
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| 52 | (fx- 8 (fxand n #x7)))
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| 53 | out))
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| 54 | (loop-y (fx+ y 1))))))))))
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| 55 |
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| 56 | ;; -------------------------------
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| 57 |
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| 58 | (time (main (string->number (car (command-line-arguments)))))
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