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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