/**
* Helper function to normalizing an array index
*
* This function clamps the given index to the [0, length] range.
* If the index is negative, it is used as the offset from the end of the array,
* to compute normalized index.
* If the index is greater than the length of the array, the normalized index will be the length of the array.
*
* See also:
* ECMA-262 v5, 15.4.4.10 steps 5-6, 7 (part 2) and 8
* ECMA-262 v5, 15.4.4.12 steps 5-6
* ECMA-262 v5, 15.4.4.14 steps 5
* ECMA-262 v5, 15.5.4.13 steps 4, 5 (part 2) and 6-7
*
* Used by:
* - The Array.prototype.slice routine.
* - The Array.prototype.splice routine.
* - The Array.prototype.indexOf routine.
* - The String.prototype.slice routine.
*
* @return uint32_t - the normalized value of the index
*/
uint32_t
ecma_builtin_helper_array_index_normalize (ecma_number_t index, /**< index */
uint32_t length) /**< array's length */
{
uint32_t norm_index;
if (!ecma_number_is_nan (index))
{
if (ecma_number_is_zero (index))
{
norm_index = 0;
}
else if (ecma_number_is_infinity (index))
{
norm_index = ecma_number_is_negative (index) ? 0 : length;
}
else
{
if (ecma_number_is_negative (index))
{
ecma_number_t index_neg = ecma_number_negate (index);
if (index_neg > length)
{
norm_index = 0;
}
else
{
norm_index = length - ecma_number_to_uint32 (index_neg);
}
}
else
{
if (index > length)
{
norm_index = length;
}
else
{
norm_index = ecma_number_to_uint32 (index);
}
}
}
}
else
{
norm_index = 0;
}
return norm_index;
} /* ecma_builtin_helper_array_index_normalize */
/**
* The Math object's 'round' routine
*
* See also:
* ECMA-262 v5, 15.8.2.15
*
* @return ecma value
* Returned value must be freed with ecma_free_value.
*/
static ecma_value_t
ecma_builtin_math_object_round (ecma_value_t this_arg __attr_unused___, /**< 'this' argument */
ecma_value_t arg) /**< routine's argument */
{
ecma_value_t ret_value = ecma_make_simple_value (ECMA_SIMPLE_VALUE_EMPTY);
ECMA_OP_TO_NUMBER_TRY_CATCH (arg_num, arg, ret_value);
ecma_number_t *num_p = ecma_alloc_number ();
if (ecma_number_is_nan (arg_num)
|| ecma_number_is_zero (arg_num)
|| ecma_number_is_infinity (arg_num))
{
*num_p = arg_num;
}
else if (ecma_number_is_negative (arg_num)
&& arg_num >= -0.5f)
{
*num_p = ecma_number_negate (0.0f);
}
else
{
const ecma_number_t up_half = arg_num + 0.5f;
const ecma_number_t down_half = arg_num - 0.5f;
const ecma_number_t up_rounded = up_half - ecma_op_number_remainder (up_half, 1);
const ecma_number_t down_rounded = down_half - ecma_op_number_remainder (down_half, 1);
if (up_rounded - arg_num <= arg_num - down_rounded)
{
*num_p = up_rounded;
}
else
{
*num_p = down_rounded;
}
}
ret_value = ecma_make_number_value (num_p);
ECMA_OP_TO_NUMBER_FINALIZE (arg_num);
return ret_value;
} /* ecma_builtin_math_object_round */
