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#include "duk_internal.h"
#if defined(DUK_USE_FASTINT)
/*
* Manually optimized double-to-fastint downgrade check.
*
* This check has a large impact on performance, especially for fastint
* slow paths, so must be changed carefully. The code should probably be
* optimized for the case where the result does not fit into a fastint,
* to minimize the penalty for "slow path code" dealing with fractions etc.
*
* At least on one tested soft float ARM platform double-to-int64 coercion
* is very slow (and sometimes produces incorrect results, see self tests).
* This algorithm combines a fastint compatibility check and extracting the
* integer value from an IEEE double for setting the tagged fastint. For
* other platforms a more naive approach might be better.
*
* See doc/fastint.rst for details.
*/
DUK_INTERNAL DUK_ALWAYS_INLINE void duk_tval_set_number_chkfast(duk_tval *tv, duk_double_t x) {
duk_double_union du;
duk_int64_t i;
duk_small_int_t expt;
duk_small_int_t shift;
/* XXX: optimize for packed duk_tval directly? */
du.d = x;
i = (duk_int64_t) DUK_DBLUNION_GET_INT64(&du);
expt = (duk_small_int_t) ((i >> 52) & 0x07ff);
shift = expt - 1023;
if (shift >= 0 && shift <= 46) { /* exponents 1023 to 1069 */
duk_int64_t t;
if (((0x000fffffffffffffLL >> shift) & i) == 0) {
t = i | 0x0010000000000000LL; /* implicit leading one */
t = t & 0x001fffffffffffffLL;
t = t >> (52 - shift);
if (i < 0) {
t = -t;
}
DUK_TVAL_SET_FASTINT(tv, t);
return;
}
} else if (shift == -1023) { /* exponent 0 */
if (i >= 0 && (i & 0x000fffffffffffffLL) == 0) {
/* Note: reject negative zero. */
DUK_TVAL_SET_FASTINT(tv, (duk_int64_t) 0);
return;
}
} else if (shift == 47) { /* exponent 1070 */
if (i < 0 && (i & 0x000fffffffffffffLL) == 0) {
DUK_TVAL_SET_FASTINT(tv, (duk_int64_t) DUK_FASTINT_MIN);
return;
}
}
DUK_TVAL_SET_DOUBLE(tv, x);
return;
}
/*
* Manually optimized number-to-double conversion
*/
#if defined(DUK_USE_FASTINT) && defined(DUK_USE_PACKED_TVAL)
DUK_INTERNAL DUK_ALWAYS_INLINE duk_double_t duk_tval_get_number_packed(duk_tval *tv) {
duk_double_union du;
duk_uint64_t t;
t = (duk_uint64_t) DUK_DBLUNION_GET_UINT64(tv);
if ((t >> 48) != DUK_TAG_FASTINT) {
return tv->d;
} else if (t & 0x0000800000000000ULL) {
t = (duk_uint64_t) (-((duk_int64_t) t)); /* avoid unary minus on unsigned */
t = t & 0x0000ffffffffffffULL; /* negative */
t |= 0xc330000000000000ULL;
DUK_DBLUNION_SET_UINT64(&du, t);
return du.d + 4503599627370496.0; /* 1 << 52 */
} else if (t != 0) {
t &= 0x0000ffffffffffffULL; /* positive */
t |= 0x4330000000000000ULL;
DUK_DBLUNION_SET_UINT64(&du, t);
return du.d - 4503599627370496.0; /* 1 << 52 */
} else {
return 0.0; /* zero */
}
}
#endif /* DUK_USE_FASTINT && DUK_USE_PACKED_TVAL */
#if 0 /* unused */
#if defined(DUK_USE_FASTINT) && !defined(DUK_USE_PACKED_TVAL)
DUK_INTERNAL DUK_ALWAYS_INLINE duk_double_t duk_tval_get_number_unpacked(duk_tval *tv) {
duk_double_union du;
duk_uint64_t t;
DUK_ASSERT(tv->t == DUK__TAG_NUMBER || tv->t == DUK_TAG_FASTINT);
if (tv->t == DUK_TAG_FASTINT) {
if (tv->v.fi >= 0) {
t = 0x4330000000000000ULL | (duk_uint64_t) tv->v.fi;
DUK_DBLUNION_SET_UINT64(&du, t);
return du.d - 4503599627370496.0; /* 1 << 52 */
} else {
t = 0xc330000000000000ULL | (duk_uint64_t) (-tv->v.fi);
DUK_DBLUNION_SET_UINT64(&du, t);
return du.d + 4503599627370496.0; /* 1 << 52 */
}
} else {
return tv->v.d;
}
}
#endif /* DUK_USE_FASTINT && DUK_USE_PACKED_TVAL */
#endif /* 0 */
#if defined(DUK_USE_FASTINT) && !defined(DUK_USE_PACKED_TVAL)
DUK_INTERNAL DUK_ALWAYS_INLINE duk_double_t duk_tval_get_number_unpacked_fastint(duk_tval *tv) {
duk_double_union du;
duk_uint64_t t;
DUK_ASSERT(tv->t == DUK_TAG_FASTINT);
if (tv->v.fi >= 0) {
t = 0x4330000000000000ULL | (duk_uint64_t) tv->v.fi;
DUK_DBLUNION_SET_UINT64(&du, t);
return du.d - 4503599627370496.0; /* 1 << 52 */
} else {
t = 0xc330000000000000ULL | (duk_uint64_t) (-tv->v.fi);
DUK_DBLUNION_SET_UINT64(&du, t);
return du.d + 4503599627370496.0; /* 1 << 52 */
}
}
#endif /* DUK_USE_FASTINT && DUK_USE_PACKED_TVAL */
#endif /* DUK_USE_FASTINT */
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