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Update comments in strtod.c

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This commit is contained in:
Calvin Rose 2019-02-17 21:44:58 -05:00
parent ffc14f6019
commit 07912f5ab2
1 changed files with 10 additions and 13 deletions
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23
src/core/strtod.c
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@ -26,23 +26,19 @@
* This version has been modified for much greater flexibility in parsing, such * This version has been modified for much greater flexibility in parsing, such
* as choosing the radix and supporting scientific notation with any radix. * as choosing the radix and supporting scientific notation with any radix.
* *
* Numbers are of the form [-+]R[rR]I.F[eE&][-+]X where R is the radix, I is * Numbers are of the form [-+]R[rR]I.F[eE&][-+]X in pseudo-regex form, where R
* the integer part, F is the fractional part, and X is the exponent. All * is the radix, I is the integer part, F is the fractional part, and X is the
* signs, radix, decimal point, fractional part, and exponent can be omitted. * exponent. All signs, radix, decimal point, fractional part, and exponent can
* The number will be considered and integer if the there is no decimal point * be omitted. The radix is assumed to be 10 if omitted, and the E or e
* and no exponent. Any number greater the 2^32-1 or less than -(2^32) will be
* coerced to a double. If there is an error, the function janet_scan_number will
* return a janet nil. The radix is assumed to be 10 if omitted, and the E
* separator for the exponent can only be used when the radix is 10. This is * separator for the exponent can only be used when the radix is 10. This is
* because E is a valid digit in bases 15 or greater. For bases greater than 10, * because E is a valid digit in bases 15 or greater. For bases greater than
* the letters are used as digits. A through Z correspond to the digits 10 * 10, the letters are used as digits. A through Z correspond to the digits 10
* through 35, and the lowercase letters have the same values. The radix number * through 35, and the lowercase letters have the same values. The radix number
* is always in base 10. For example, a hexidecimal number could be written * is always in base 10. For example, a hexidecimal number could be written
* '16rdeadbeef'. janet_scan_number also supports some c style syntax for * '16rdeadbeef'. janet_scan_number also supports some c style syntax for
* hexidecimal literals. The previous number could also be written * hexidecimal literals. The previous number could also be written
* '0xdeadbeef'. Note that in this case, the number will actually be a double * '0xdeadbeef'.
* as it will not fit in the range for a signed 32 bit integer. The string */
* '0xbeef' would parse to an integer as it is in the range of an int32_t. */
#include <math.h> #include <math.h>
#include <string.h> #include <string.h>
@ -75,6 +71,7 @@ struct BigNat {
uint32_t *digits; /* Each digit is base (2 ^ 31). Digits are least significant first. */ uint32_t *digits; /* Each digit is base (2 ^ 31). Digits are least significant first. */
}; };
/* Initialize a bignat to 0 */
static void bignat_zero(struct BigNat *x) { static void bignat_zero(struct BigNat *x) {
x->first_digit = 0; x->first_digit = 0;
x->n = 0; x->n = 0;
@ -197,7 +194,7 @@ static double bignat_extract(struct BigNat *mant, int32_t exponent2) {
} }
/* Read in a mantissa and exponent of a certain base, and give /* Read in a mantissa and exponent of a certain base, and give
* back the double value. Should properly handle 0s, Infinities, and * back the double value. Should properly handle 0s, infinities, and
* denormalized numbers. (When the exponent values are too large) */ * denormalized numbers. (When the exponent values are too large) */
static double convert( static double convert(
int negative, int negative,