Szabolcs Nagy
662ed20065
old code (return x+x;) returns correct value and raises correct flags only if the result is stored as double (or float)
46 lines
799 B
C
46 lines
799 B
C
#include "libm.h"
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#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
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double nexttoward(double x, long double y)
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{
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return nextafter(x, y);
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}
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#else
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#define SIGN ((uint64_t)1<<63)
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double nexttoward(double x, long double y)
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{
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union dshape ux;
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int e;
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if (isnan(x) || isnan(y))
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return x + y;
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if (x == y)
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return y;
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ux.value = x;
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if (x == 0) {
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ux.bits = 1;
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if (signbit(y))
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ux.bits |= SIGN;
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} else if (x < y) {
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if (signbit(x))
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ux.bits--;
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else
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ux.bits++;
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} else {
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if (signbit(x))
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ux.bits++;
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else
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ux.bits--;
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}
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e = ux.bits>>52 & 0x7ff;
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/* raise overflow if ux.value is infinite and x is finite */
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if (e == 0x7ff)
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FORCE_EVAL(x+x);
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/* raise underflow if ux.value is subnormal or zero */
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if (e == 0)
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FORCE_EVAL(x*x + ux.value*ux.value);
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return ux.value;
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}
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#endif
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