Mercurial > sdl-ios-xcode
annotate README.DirectFB @ 2752:edd2839b36f7
http://sources.redhat.com/ml/newlib/2002/msg00230.html
Stephen L Moshier wrote:
>
> pow(x,y) returns 0 when x is very close to -1.0 and y is very large.
> The following test program prints
>
> pow(1.0000000000000002e+00 4.5035996273704970e+15) = 2.7182818284590455e+00
> pow(-1.0000000000000002e+00 4.5035996273704970e+15) =0.0000000000000000e+00
> pow(9.9999999999999978e-01 4.5035996273704970e+15) = 3.6787944117144222e-01
> pow(-9.9999999999999978e-01 4.5035996273704970e+15) = 0.0000000000000000e+00
>
> which is incorrect for the negative arguments raised to an odd integer
> power.
>
> -----
> double pow (double, double);
>
> int
> main ()
> {
> double x, y, z;
>
> x = 1.0 + pow (2.0, -52.0);
> y = 1.0 + pow (2.0, 52.0);
> z = pow (x, y);
> printf ("pow(%.16e %.16e) = %.16e\n", x, y, z);
> x = -x;
> z = pow (x, y);
> printf ("pow(%.16e %.16e) = %.16e\n", x, y, z);
> x = 1.0 - pow (2.0, -52.0);
> z = pow (x, y);
> printf ("pow(%.16e %.16e) = %.16e\n", x, y, z);
> x = -x;
> z = pow (x, y);
> printf ("pow(%.16e %.16e) = %.16e\n", x, y, z);
> }
> -----
>
> Here is a patch for newlib/libm/math/epow.c:
Patch checked in and duplicated for ef_pow.c. Thanks.
-- Jeff J.
| author | Sam Lantinga <slouken@libsdl.org> |
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| date | Mon, 15 Sep 2008 04:31:30 +0000 |
| parents | 0e70b4b8cf84 |
| children | 8133d1d278da |
| rev | line source |
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0e70b4b8cf84
Date: Sat, 11 Aug 2007 02:03:16 +0200 (CEST)
Sam Lantinga <slouken@libsdl.org>
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1 SDL on DirectFB |
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Date: Sat, 11 Aug 2007 02:03:16 +0200 (CEST)
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2 |
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3 Supports: |
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4 |
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5 - Hardware YUV overlays |
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6 - OpenGL - software only |
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7 - 2D/3D accelerations (depends on directfb driver) |
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8 |
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Date: Sat, 11 Aug 2007 02:03:16 +0200 (CEST)
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9 What you need: |
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10 |
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Date: Sat, 11 Aug 2007 02:03:16 +0200 (CEST)
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11 DirectFB 1.0.0 - required |
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12 Kernel-Framebuffer support: required: vesafb, radeonfb .... |
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13 Mesa 7.0.x - optional for OpenGL |
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14 |
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Date: Sat, 11 Aug 2007 02:03:16 +0200 (CEST)
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15 As of this writing 20070810 you need to pull Mesa from git and do the following: |
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16 |
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17 ------------------------ |
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18 cd mesa |
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19 make linux-directfb |
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20 make |
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21 |
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22 echo Installing - pleaser enter sudo pw. |
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23 |
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24 sudo make install INSTALL_DIR=/usr/local/dfb_GL |
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25 cd src/mesa/drivers/directfb |
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Date: Sat, 11 Aug 2007 02:03:16 +0200 (CEST)
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26 make |
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27 sudo make install INSTALL_DIR=/usr/local/dfb_GL |
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28 ------------------------ |
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29 |
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30 To run the SDL - testprograms: |
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31 |
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32 export SDL_VIDEODRIVER=directfb |
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33 export LD_LIBRARY_PATH=/usr/local/dfb_GL/lib |
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34 export LD_PRELOAD=/usr/local/dfb_GL/libGL.so.7 |
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35 |
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Date: Sat, 11 Aug 2007 02:03:16 +0200 (CEST)
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36 ./testgl |
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37 |
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Date: Sat, 11 Aug 2007 02:03:16 +0200 (CEST)
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38 To use hardware accelerated YUV-overlays for YUV-textures, use: |
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0e70b4b8cf84
Date: Sat, 11 Aug 2007 02:03:16 +0200 (CEST)
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39 |
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0e70b4b8cf84
Date: Sat, 11 Aug 2007 02:03:16 +0200 (CEST)
Sam Lantinga <slouken@libsdl.org>
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40 export SDL_DIRECTFB_YUV_DIRECT=1 |
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0e70b4b8cf84
Date: Sat, 11 Aug 2007 02:03:16 +0200 (CEST)
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41 |
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Date: Sat, 11 Aug 2007 02:03:16 +0200 (CEST)
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42 This is disabled by default. It will only support one concurrent |
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Date: Sat, 11 Aug 2007 02:03:16 +0200 (CEST)
Sam Lantinga <slouken@libsdl.org>
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43 overlay and may behave strange if not used with SDL_CreateYUvOverlay |
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0e70b4b8cf84
Date: Sat, 11 Aug 2007 02:03:16 +0200 (CEST)
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44 from SDLcompat.c. |
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Date: Sat, 11 Aug 2007 02:03:16 +0200 (CEST)
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45 |