69 lines
1.9 KiB
C
69 lines
1.9 KiB
C
#define BIAS80 16383
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#define BIAS64 1023
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typedef struct {
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int16_t begin;
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union {
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double d;
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uint64_t ll;
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} eind;
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} x87_conv_t;
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static __inline double x87_from80(x87_conv_t *test)
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{
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int64_t exp64;
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int64_t blah;
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int64_t exp64final;
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int64_t mant64;
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int64_t sign;
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exp64 = (((test->begin&0x7fff) - BIAS80));
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blah = ((exp64 >0)?exp64:-exp64)&0x3ff;
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exp64final = ((exp64 >0)?blah:-blah) +BIAS64;
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mant64 = (test->eind.ll >> 11) & (0xfffffffffffffll);
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sign = (test->begin&0x8000)?1:0;
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if ((test->begin & 0x7fff) == 0x7fff)
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exp64final = 0x7ff;
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if ((test->begin & 0x7fff) == 0)
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exp64final = 0;
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if (test->eind.ll & 0x400)
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mant64++;
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test->eind.ll = (sign <<63)|(exp64final << 52)| mant64;
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return test->eind.d;
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}
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static __inline void x87_to80(double d, x87_conv_t *test)
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{
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int64_t sign80;
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int64_t exp80;
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int64_t exp80final;
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int64_t mant80;
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int64_t mant80final;
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test->eind.d=d;
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sign80 = (test->eind.ll&(0x8000000000000000ll))?1:0;
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exp80 = test->eind.ll&(0x7ff0000000000000ll);
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exp80final = (exp80>>52);
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mant80 = test->eind.ll&(0x000fffffffffffffll);
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mant80final = (mant80 << 11);
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if (exp80final == 0x7ff) /*Infinity / Nan*/
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{
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exp80final = 0x7fff;
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mant80final |= (0x8000000000000000ll);
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}
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else if (d != 0){ /* Zero is a special case */
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/* Elvira wants the 8 and tcalc doesn't */
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mant80final |= (0x8000000000000000ll);
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/* Ca-cyber doesn't like this when result is zero. */
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exp80final += (BIAS80 - BIAS64);
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}
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test->begin = (((int16_t)sign80)<<15)| (int16_t)exp80final;
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test->eind.ll = mant80final;
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}
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