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111
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1 /*
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2 * inspired by glibc-2.0.6/sysdeps/libm-ieee754/s_nextafterf.c
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3 *
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4 * gcc -O2 -S -DOP=+ gives faddp %st(1),%st
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5 * gcc -O2 -S -DOP=* gives fmulp %st(1),%st
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6 * gcc -O2 -S -DOP=- gives fsubrp %st(1),%st
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7 * gcc -O2 -S -DOP=/ gives fdivrp %st(1),%st
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8 */
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9
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10 #ifndef OP
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11 #define OP *
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12 #endif
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13
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14 typedef int int32_t __attribute__ ((__mode__ ( __SI__ ))) ;
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15 typedef unsigned int u_int32_t __attribute__ ((__mode__ ( __SI__ ))) ;
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16
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17 typedef union
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18 {
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19 float value;
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20 u_int32_t word;
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21 } ieee_float_shape_type;
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22
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23 float __nextafterf(float x, float y)
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24 {
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25 int32_t hx,hy,ix,iy;
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26
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27 {
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28 ieee_float_shape_type gf_u;
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29 gf_u.value = x;
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30 hx = gf_u.word;
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31 }
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32 {
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33 ieee_float_shape_type gf_u;
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34 gf_u.value = y;
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35 hy = gf_u.word;
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36 }
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37 ix = hx&0x7fffffff;
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38 iy = hy&0x7fffffff;
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39
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40 if ( ix > 0x7f800000 || iy > 0x7f800000 )
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41 return x+y;
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42 if (x == y) return x;
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43 if (ix == 0)
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44 {
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45 {
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46 ieee_float_shape_type sf_u;
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47 sf_u.word = (hy&0x80000000) | 1;
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48 x = sf_u.value;
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49 }
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50 y = x*x;
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51 if (y == x) return y; else return x;
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52 }
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53 if (hx >= 0)
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54 {
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55 if (hx > hy)
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56 hx -= 1;
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57 else
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58 hx += 1;
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59 }
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60 else
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61 {
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62 if (hy >= 0 || hx > hy)
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63 hx -= 1;
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64 else
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65 hx += 1;
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66 }
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67 hy = hx & 0x7f800000;
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68 if (hy >= 0x7f800000)
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69 return x+x;
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70 if (hy < 0x00800000)
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71 {
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72 y = x OP x;
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73 if (y != x)
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74 {
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75 ieee_float_shape_type sf_u;
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76 sf_u.word = hx;
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77 y = sf_u.value;
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78 return y;
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79 }
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80 }
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81 {
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82 ieee_float_shape_type sf_u;
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83 sf_u.word = hx;
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84 x = sf_u.value;
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85 }
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86 return x;
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87 }
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88
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89
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