Last change
on this file since 559 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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Rev | Line | |
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[444] | 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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