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annotate src/libm/s_scalbn.c @ 4593:3892fe2f6537

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Fixed so many things. See the changelog listed below. 1. Use SDL_X11_HAVE_XRENDER to check for RENDER at runtime. 2. Added lots of comments. 3. Added checks and lots of calls to SDL_SetError(). 4. Fixed X11_CreateTexture() so that the pixmap and image created are for the format specified by the user and not the window format. This is only for the RENDER case. 5. The above change required that functions to convert SDL pixel format enums to Visuals and XRenderPictFormats be added. 6. Fixed lots of 'style' issues.
author Sunny Sachanandani <sunnysachanandani@gmail.com>
date Sat, 17 Jul 2010 15:38:24 +0530
parents 9ac6f0782dd6
children
rev   line source
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a98604b691c8 Expanded the libm support and put it into a separate directory.
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1 /* @(#)s_scalbn.c 5.1 93/09/24 */
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2 /*
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3 * ====================================================
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4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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5 *
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6 * Developed at SunPro, a Sun Microsystems, Inc. business.
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7 * Permission to use, copy, modify, and distribute this
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8 * software is freely granted, provided that this notice
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9 * is preserved.
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10 * ====================================================
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11 */
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12
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13 #if defined(LIBM_SCCS) && !defined(lint)
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14 static const char rcsid[] =
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15 "$NetBSD: s_scalbn.c,v 1.8 1995/05/10 20:48:08 jtc Exp $";
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16 #endif
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17
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18 /*
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19 * scalbn (double x, int n)
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20 * scalbn(x,n) returns x* 2**n computed by exponent
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21 * manipulation rather than by actually performing an
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22 * exponentiation or a multiplication.
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23 */
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24
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25 #include "math.h"
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26 #include "math_private.h"
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27
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28 libm_hidden_proto(copysign)
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29 #ifdef __STDC__
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30 static const double
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31 #else
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32 static double
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33 #endif
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34 two54 = 1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
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35 twom54 = 5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */
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36 huge_val = 1.0e+300, tiny = 1.0e-300;
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37
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38 libm_hidden_proto(scalbn)
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39 #ifdef __STDC__
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40 double scalbn(double x, int n)
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41 #else
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42 double scalbn(x, n)
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43 double x;
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44 int n;
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45 #endif
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46 {
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47 int32_t k, hx, lx;
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48 EXTRACT_WORDS(hx, lx, x);
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49 k = (hx & 0x7ff00000) >> 20; /* extract exponent */
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50 if (k == 0) { /* 0 or subnormal x */
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51 if ((lx | (hx & 0x7fffffff)) == 0)
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52 return x; /* +-0 */
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53 x *= two54;
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54 GET_HIGH_WORD(hx, x);
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55 k = ((hx & 0x7ff00000) >> 20) - 54;
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56 if (n < -50000)
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57 return tiny * x; /*underflow */
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58 }
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59 if (k == 0x7ff)
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60 return x + x; /* NaN or Inf */
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61 k = k + n;
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62 if (k > 0x7fe)
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63 return huge_val * copysign(huge_val, x); /* overflow */
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64 if (k > 0) { /* normal result */
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65 SET_HIGH_WORD(x, (hx & 0x800fffff) | (k << 20));
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66 return x;
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67 }
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68 if (k <= -54) {
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69 if (n > 50000) /* in case integer overflow in n+k */
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70 return huge_val * copysign(huge_val, x); /*overflow */
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71 else
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72 return tiny * copysign(tiny, x); /*underflow */
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73 }
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74 k += 54; /* subnormal result */
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75 SET_HIGH_WORD(x, (hx & 0x800fffff) | (k << 20));
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76 return x * twom54;
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77 }
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78
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79 libm_hidden_def(scalbn)