Last change
on this file since 466 was
444,
checked in by satin@…, 6 years ago
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add newlib,libalmos-mkh, restructure shared_syscalls.h and mini-libc
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File size:
1.4 KB
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Line | |
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1 | |
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2 | /* @(#)z_ldexpf.c 1.0 98/08/13 */ |
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3 | /****************************************************************** |
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4 | * ldexp |
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5 | * |
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6 | * Input: |
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7 | * d - a floating point value |
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8 | * e - an exponent value |
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9 | * |
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10 | * Output: |
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11 | * A floating point value f such that f = d * 2 ^ e. |
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12 | * |
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13 | * Description: |
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14 | * This function creates a floating point number f such that |
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15 | * f = d * 2 ^ e. |
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16 | * |
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17 | *****************************************************************/ |
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18 | |
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19 | #include <float.h> |
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20 | #include "fdlibm.h" |
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21 | #include "zmath.h" |
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22 | |
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23 | #define FLOAT_EXP_OFFS 127 |
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24 | |
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25 | float |
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26 | ldexpf (float d, |
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27 | int e) |
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28 | { |
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29 | int exp; |
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30 | __int32_t wd; |
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31 | |
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32 | GET_FLOAT_WORD (wd, d); |
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33 | |
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34 | /* Check for special values and then scale d by e. */ |
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35 | switch (numtestf (wd)) |
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36 | { |
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37 | case NAN: |
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38 | errno = EDOM; |
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39 | break; |
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40 | |
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41 | case INF: |
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42 | errno = ERANGE; |
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43 | break; |
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44 | |
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45 | case 0: |
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46 | break; |
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47 | |
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48 | default: |
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49 | exp = (wd & 0x7f800000) >> 23; |
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50 | exp += e; |
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51 | |
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52 | if (exp > FLT_MAX_EXP + FLOAT_EXP_OFFS) |
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53 | { |
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54 | errno = ERANGE; |
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55 | d = z_infinity_f.f; |
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56 | } |
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57 | else if (exp < FLT_MIN_EXP + FLOAT_EXP_OFFS) |
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58 | { |
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59 | errno = ERANGE; |
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60 | d = -z_infinity_f.f; |
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61 | } |
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62 | else |
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63 | { |
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64 | wd &= 0x807fffff; |
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65 | wd |= exp << 23; |
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66 | SET_FLOAT_WORD (d, wd); |
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67 | } |
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68 | } |
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69 | |
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70 | return (d); |
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71 | } |
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72 | |
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73 | #ifdef _DOUBLE_IS_32BITS |
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74 | |
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75 | double ldexp (double x, int e) |
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76 | { |
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77 | return (double) ldexpf ((float) x, e); |
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78 | } |
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79 | |
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80 | #endif /* defined(_DOUBLE_IS_32BITS) */ |
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