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2 #ifdef DM_USE_SIMD
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3 static int DM_DRAWLINE_NAME_ASM (SDL_Surface *screen, int x0, int y0, int x1, int y1, const Uint32 col);
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4 #endif
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5
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6 #ifdef DM_USE_C
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7 static int DM_DRAWLINE_NAME_C (SDL_Surface *screen, int x0, int y0, int x1, int y1, const Uint32 col)
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8 {
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9 int dx, dy, xstep, ystep;
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10 const int qpitch = screen->pitch / DM_DRAWLINE_DST_BYTES;
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11
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12 // Clipping
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13 if (dmClipLineCoords(&x0, &y0, &x1, &y1, screen))
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14 return -1;
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15
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16 // Compute initial deltas
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17 dx = (x1 - x0) * 2;
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18 dy = (y1 - y0) * 2;
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19
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20 if (dx < 0)
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21 {
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22 dx = -dx;
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23 xstep = -1;
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24 }
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25 else
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26 xstep = 1;
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27
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28 if (dy < 0)
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29 {
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30 dy = -dy;
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31 ystep = -qpitch;
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32 }
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33 else
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34 ystep = qpitch;
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35
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36 // Compute offsets
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37 y0 *= qpitch;
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38 y1 *= qpitch;
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39
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40 DM_DRAWLINE_DST_TYPE *pix = screen->pixels;
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41
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42 // Continue based on which delta is larger
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43 if (dx > dy)
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44 {
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45 int afrac = dy - (dx / 2);
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46 while (x0 != x1)
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47 {
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48 if (afrac >= 0)
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49 {
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50 y0 += ystep;
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51 afrac -= dx;
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52 }
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53
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54 x0 += xstep;
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55 afrac += dy;
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56
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57 DM_DRAWLINE_INNER
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58 }
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59 }
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60 else
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61 {
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62 int afrac = dx - (dy / 2);
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63 while (y0 != y1)
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64 {
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65 if (afrac >= 0)
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66 {
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67 x0 += xstep;
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68 afrac -= dy;
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69 }
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70
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71 y0 += ystep;
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72 afrac += dx;
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73
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74 DM_DRAWLINE_INNER
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75 }
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76 }
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77
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78 return 0;
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79 }
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80 #endif
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81
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82 #undef DM_DRAWLINE_NAME
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83 #undef DM_DRAWLINE_NAME_ASM
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84 #undef DM_DRAWLINE_NAME_C
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85 #undef DM_DRAWLINE_DST_BYTES
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86 #undef DM_DRAWLINE_DST_TYPE
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