DUK_INTERNAL duk_double_t duk_double_trunc_towards_zero(duk_double_t x) {
/* XXX: optimize */
duk_small_int_t s = duk_double_signbit(x);
x = DUK_FLOOR(DUK_FABS(x)); /* truncate towards zero */
if (s) {
x = -x;
}
return x;
}
/* exposed, used by e.g. duk_bi_date.c */
DUK_INTERNAL duk_double_t duk_js_tointeger_number(duk_double_t x) {
duk_small_int_t c = (duk_small_int_t) DUK_FPCLASSIFY(x);
if (c == DUK_FP_NAN) {
return 0.0;
} else if (c == DUK_FP_ZERO || c == DUK_FP_INFINITE) {
/* XXX: FP_ZERO check can be removed, the else clause handles it
* correctly (preserving sign).
*/
return x;
} else {
duk_small_int_t s = (duk_small_int_t) DUK_SIGNBIT(x);
x = DUK_FLOOR(DUK_FABS(x)); /* truncate towards zero */
if (s) {
x = -x;
}
return x;
}
}
/* combined algorithm matching E5 Sections 9.5 and 9.6 */
DUK_LOCAL duk_double_t duk__toint32_touint32_helper(duk_double_t x, duk_bool_t is_toint32) {
duk_small_int_t c = (duk_small_int_t) DUK_FPCLASSIFY(x);
duk_small_int_t s;
if (c == DUK_FP_NAN || c == DUK_FP_ZERO || c == DUK_FP_INFINITE) {
return 0.0;
}
/* x = sign(x) * floor(abs(x)), i.e. truncate towards zero, keep sign */
s = (duk_small_int_t) DUK_SIGNBIT(x);
x = DUK_FLOOR(DUK_FABS(x));
if (s) {
x = -x;
}
/* NOTE: fmod(x) result sign is same as sign of x, which
* differs from what Javascript wants (see Section 9.6).
*/
x = DUK_FMOD(x, DUK_DOUBLE_2TO32); /* -> x in ]-2**32, 2**32[ */
if (x < 0.0) {
x += DUK_DOUBLE_2TO32;
}
/* -> x in [0, 2**32[ */
if (is_toint32) {
if (x >= DUK_DOUBLE_2TO31) {
/* x in [2**31, 2**32[ */
x -= DUK_DOUBLE_2TO32; /* -> x in [-2**31,2**31[ */
}
}
return x;
}
DUK_INTERNAL duk_ret_t duk_bi_math_object_hypot(duk_context *ctx) {
/*
* E6 Section 20.2.2.18: Math.hypot
*
* - If no arguments are passed, the result is +0.
* - If any argument is +inf, the result is +inf.
* - If any argument is -inf, the result is +inf.
* - If no argument is +inf or -inf, and any argument is NaN, the result is
* NaN.
* - If all arguments are either +0 or -0, the result is +0.
*/
duk_idx_t nargs;
duk_idx_t i;
duk_bool_t found_nan;
duk_double_t max;
duk_double_t sum, summand;
duk_double_t comp, prelim;
duk_double_t t;
nargs = duk_get_top(ctx);
/* Find the highest value. Also ToNumber() coerces. */
max = 0.0;
found_nan = 0;
for (i = 0; i < nargs; i++) {
t = DUK_FABS(duk_to_number(ctx, i));
if (DUK_FPCLASSIFY(t) == DUK_FP_NAN) {
found_nan = 1;
} else {
max = duk_double_fmax(max, t);
}
}
/* Early return cases. */
if (max == DUK_DOUBLE_INFINITY) {
duk_push_number(ctx, DUK_DOUBLE_INFINITY);
return 1;
} else if (found_nan) {
duk_push_number(ctx, DUK_DOUBLE_NAN);
return 1;
} else if (max == 0.0) {
duk_push_number(ctx, 0.0);
/* Otherwise we'd divide by zero. */
return 1;
}
/* Use Kahan summation and normalize to the highest value to minimize
* floating point rounding error and avoid overflow.
*
* https://en.wikipedia.org/wiki/Kahan_summation_algorithm
*/
sum = 0.0;
comp = 0.0;
for (i = 0; i < nargs; i++) {
t = DUK_FABS(duk_get_number(ctx, i)) / max;
summand = (t * t) - comp;
prelim = sum + summand;
comp = (prelim - sum) - summand;
sum = prelim;
}
duk_push_number(ctx, (duk_double_t) DUK_SQRT(sum) * max);
return 1;
}
DUK_LOCAL double duk__fabs(double x) {
return DUK_FABS(x);
}
static double duk__pow_fixed(double x, double y) {
/* The ANSI C pow() semantics differ from Ecmascript.
*
* E.g. when x==1 and y is +/- infinite, the Ecmascript required
* result is NaN, while at least Linux pow() returns 1.
*/
int cx, cy, sx;
DUK_UNREF(cx);
DUK_UNREF(sx);
cy = DUK_FPCLASSIFY(y);
if (cy == DUK_FP_NAN) {
goto ret_nan;
}
if (DUK_FABS(x) == 1.0 && cy == DUK_FP_INFINITE) {
goto ret_nan;
}
#if defined(DUK_USE_POW_NETBSD_WORKAROUND)
/* See test-bug-netbsd-math-pow.js: NetBSD 6.0 on x86 (at least) does not
* correctly handle some cases where x=+/-0. Specific fixes to these
* here.
*/
cx = DUK_FPCLASSIFY(x);
if (cx == DUK_FP_ZERO && y < 0.0) {
sx = DUK_SIGNBIT(x);
if (sx == 0) {
/* Math.pow(+0,y) should be Infinity when y<0. NetBSD pow()
* returns -Infinity instead when y is <0 and finite. The
* if-clause also catches y == -Infinity (which works even
* without the fix).
*/
return DUK_DOUBLE_INFINITY;
} else {
/* Math.pow(-0,y) where y<0 should be:
* - -Infinity if y<0 and an odd integer
* - Infinity otherwise
* NetBSD pow() returns -Infinity for all finite y<0. The
* if-clause also catches y == -Infinity (which works even
* without the fix).
*/
/* fmod() return value has same sign as input (negative) so
* the result here will be in the range ]-2,0], 1 indicates
* odd. If x is -Infinity, NaN is returned and the odd check
* always concludes "not odd" which results in desired outcome.
*/
double tmp = DUK_FMOD(y, 2);
if (tmp == -1.0) {
return -DUK_DOUBLE_INFINITY;
} else {
/* Not odd, or y == -Infinity */
return DUK_DOUBLE_INFINITY;
}
}
}
#endif
return DUK_POW(x, y);
ret_nan:
return DUK_DOUBLE_NAN;
}