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| 4973 | right-hear | 1 | /* Copyright (C) 1994 DJ Delorie, see COPYING.DJ for details */ |
| 2 | #include |
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| 3 | |||
| 4 | double |
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| 5 | frexp(double x, int *exptr) |
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| 6 | { |
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| 7 | union { |
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| 8 | double d; |
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| 9 | unsigned char c[8]; |
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| 10 | } u; |
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| 11 | |||
| 12 | u.d = x; |
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| 13 | /* |
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| 14 | * The format of the number is: |
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| 15 | * Sign, 12 exponent bits, 51 mantissa bits |
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| 16 | * The exponent is 1023 biased and there is an implicit zero. |
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| 17 | * We get the exponent from the upper bits and set the exponent |
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| 18 | * to 0x3fe (1022). |
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| 19 | */ |
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| 20 | *exptr = (int)(((u.c[7] & 0x7f) << 4) | (u.c[6] >> 4)) - 1022; |
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| 21 | u.c[7] &= 0x80; |
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| 22 | u.c[7] |= 0x3f; |
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| 23 | u.c[6] &= 0x0f; |
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| 24 | u.c[6] |= 0xe0; |
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| 25 | return u.d; |
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| 26 | } |