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1268
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1 /* magstep.c: fix up fixed-point vs. floating-point. |
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2 |
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3 Copyright (C) 1994 Karl Berry. |
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4 |
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5 This program is free software; you can redistribute it and/or modify |
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6 it under the terms of the GNU General Public License as published by |
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7 the Free Software Foundation; either version 2, or (at your option) |
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8 any later version. |
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9 |
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10 This program is distributed in the hope that it will be useful, |
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11 but WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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13 GNU General Public License for more details. |
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14 |
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15 You should have received a copy of the GNU General Public License |
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16 along with this program; if not, write to the Free Software |
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17 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ |
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18 |
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19 #include <kpathsea/config.h> |
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20 |
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21 #include <kpathsea/magstep.h> |
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22 |
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23 |
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24 /* Return true magstep N, where the lsb of N means ``half'' (see |
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25 magstep.h) for resolution BDPI. From Tom Rokicki's dvips. */ |
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26 |
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27 static int |
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28 magstep P2C(int, n, int, bdpi) |
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29 { |
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30 double t; |
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31 int step; |
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32 int neg = 0; |
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33 |
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34 if (n < 0) |
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35 { |
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36 neg = 1; |
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37 n = -n; |
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38 } |
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39 |
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40 if (n & 1) |
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41 { |
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42 n &= ~1; |
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43 t = 1.095445115; |
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44 } |
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45 else |
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46 t = 1.0; |
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47 |
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48 while (n > 8) |
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49 { |
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50 n -= 8; |
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51 t = t * 2.0736; |
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52 } |
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53 |
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54 while (n > 0) |
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55 { |
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56 n -= 2; |
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57 t = t * 1.2; |
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58 } |
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59 |
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60 step = 0.5 + (neg ? bdpi / t : bdpi * t); |
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61 return step; |
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62 } |
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63 |
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64 /* This is adapted from code written by Tom Rokicki for dvips. It's |
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65 part of Kpathsea now so all the drivers can use it. The idea is to |
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66 return the true dpi corresponding to DPI with a base resolution of |
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67 BDPI. If M_RET is non-null, we also set that to the mag value. */ |
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68 |
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69 /* Don't bother trying to use fabs or some other ``standard'' routine |
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70 which can only cause trouble; just roll our own simple-minded |
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71 absolute-value function that is all we need. */ |
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72 #undef ABS /* be safe */ |
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73 #define ABS(expr) ((expr) < 0 ? -(expr) : (expr)) |
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74 |
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75 #define MAGSTEP_MAX 40 |
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76 |
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77 unsigned |
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78 kpse_magstep_fix P3C(unsigned, dpi, unsigned, bdpi, int *, m_ret) |
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79 { |
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80 int m; |
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81 int mdpi = -1; |
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82 unsigned real_dpi = 0; |
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83 int sign = dpi < bdpi ? -1 : 1; /* negative or positive magsteps? */ |
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84 |
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85 for (m = 0; !real_dpi && m < MAGSTEP_MAX; m++) /* don't go forever */ |
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86 { |
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87 mdpi = magstep (m * sign, bdpi); |
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88 if (ABS (mdpi - (int) dpi) <= 1) /* if this magstep matches, quit */ |
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89 real_dpi = mdpi; |
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90 else if ((mdpi - (int) dpi) * sign > 0) /* if gone too far, quit */ |
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91 real_dpi = dpi; |
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92 } |
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93 |
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94 /* If requested, return the encoded magstep (the loop went one too far). */ |
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95 if (m_ret) |
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96 *m_ret = real_dpi == mdpi ? (m - 1) * sign : 0; |
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97 |
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98 /* Always return the true dpi found. */ |
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99 return real_dpi ? real_dpi : dpi; |
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100 } |
