37 lines
1.2 KiB
C
37 lines
1.2 KiB
C
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/* Public domain. */
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typedef int DItype __attribute__ ((mode (DI)));
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typedef unsigned int UDItype __attribute__ ((mode (DI)));
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typedef unsigned int USItype __attribute__ ((mode (SI)));
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typedef float SFtype __attribute__ ((mode (SF)));
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typedef float DFtype __attribute__ ((mode (DF)));
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SFtype __floatundisf (UDItype);
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SFtype
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__floatundisf (UDItype u)
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{
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/* Protect against double-rounding error.
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Represent any low-order bits, that might be truncated by a bit that
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won't be lost. The bit can go in anywhere below the rounding position
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of SFTYPE. A fixed mask and bit position handles all usual
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configurations. */
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if (53 < (sizeof (DItype) * 8)
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&& 53 > ((sizeof (DItype) * 8) - 53 + 24))
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{
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if (u >= ((UDItype) 1 << 53))
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{
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if ((UDItype) u & (((UDItype) 1 << (sizeof (DItype) * 8 - 53)) - 1))
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{
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u &= ~ (((UDItype) 1 << (sizeof (DItype) * 8 - 53)) - 1);
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u |= (UDItype) 1 << (sizeof (DItype) * 8 - 53);
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}
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}
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}
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/* Do the calculation in a wider type so that we don't lose any of
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the precision of the high word while multiplying it. */
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DFtype f = (USItype) (u >> (sizeof (USItype) * 8));
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f *= 0x1p32f;
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f += (USItype) u;
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return (SFtype) f;
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}
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