mirror of
https://github.com/janet-lang/janet
synced 2024-12-26 00:10:27 +00:00
Work on number code for more expected behavior and better rounding.
Still needs work and testing.
This commit is contained in:
Calvin Rose
parent
424073bbb8
commit
5c84f0f5d9
@ -31,11 +31,11 @@ static JanetSlot multisym_parse_part(JanetCompiler *c, const uint8_t *sympart, i
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return janetc_cslot(janet_symbolv(sympart, len));
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} else {
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int err = 0;
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int32_t num = janet_scan_integer(sympart + 1, len - 1, &err);
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double num = janet_scan_number(sympart + 1, len - 1, &err);
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if (err) {
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return janetc_resolve(c, janet_symbol(sympart + 1, len - 1));
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} else {
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return janetc_cslot(janet_wrap_integer(num));
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return janetc_cslot(janet_wrap_number(num));
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}
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}
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}
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@ -107,7 +107,7 @@ const uint8_t *janet_cstring(const char *str) {
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#define BUFSIZE 64
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static int32_t number_to_string_impl(uint8_t *buf, double x) {
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int count = snprintf((char *) buf, BUFSIZE, "%.17g", x);
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int count = snprintf((char *) buf, BUFSIZE, "%g", x);
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return (int32_t) count;
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}
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@ -51,6 +51,7 @@
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#include <janet/janet.h>
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#include <math.h>
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#include <string.h>
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/* Lookup table for getting values of characters when parsing numbers. Handles
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* digits 0-9 and a-z (and A-Z). A-Z have values of 10 to 35. */
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@ -65,98 +66,217 @@ static uint8_t digit_lookup[128] = {
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25,26,27,28,29,30,31,32,33,34,35,0xff,0xff,0xff,0xff,0xff
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};
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#define MANT_NBIT 27
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#define MANT_BASE 0x8000000
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/* Allow for BigInt mantissa. Mant is a natural number. */
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struct Mant {
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uint32_t first_digit; /* First digit so we don't need to allocate when not needed. */
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int32_t n; /* n digits */
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int32_t cap; /* allocated digit capacity */
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uint32_t *digits; /* Each digit is base (2 ^ 31). Digits are least significant first. */
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};
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/* Print number */
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static void mant_debug(struct Mant *mant) {
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printf("<bigint: 0x%x", mant->first_digit);
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for (int i = 0; i < mant->n; i++) {
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printf(" 0x%x", mant->digits[i]);
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}
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printf(">\n");
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}
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/* Allocate n more digits for mant. Return a pointer to these digits. */
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static uint32_t *mant_extra(struct Mant *mant, int32_t n) {
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int32_t oldn = mant->n;
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int32_t newn = oldn + n;
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if (mant->cap < newn) {
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int32_t newcap = 2 * newn;
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uint32_t *mem = realloc(mant->digits, newcap * sizeof(uint32_t));
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if (NULL == mem) {
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JANET_OUT_OF_MEMORY;
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}
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mant->cap = newcap;
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mant->digits = mem;
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}
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mant->n = newn;
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return mant->digits + oldn;
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}
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/* Append a digit */
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static void mant_append(struct Mant *mant, uint32_t dig) {
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mant_extra(mant, 1)[0] = dig;
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}
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/* Add term to mant */
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static void mant_add(struct Mant *mant, uint32_t dig) {
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int32_t i;
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int carry = 0;
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uint32_t next = mant->first_digit + dig;
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if (next >= MANT_BASE) {
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next -= MANT_BASE;
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carry = 1;
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}
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mant->first_digit = next;
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for (i = 0; i < mant->n; i++) {
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if (!carry) return;
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uint32_t next = mant->digits[i] + 1;
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if (next >= MANT_BASE) {
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next = 0;
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} else {
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carry = 0;
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}
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mant->digits[i] = next;
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}
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if (carry) mant_append(mant, 1);
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}
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/* Multiply the mantissa mant by a factor */
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static void mant_mul(struct Mant *mant, uint32_t factor) {
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int32_t i;
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uint64_t carry = mant->first_digit * factor;
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mant->first_digit = carry % MANT_BASE;
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carry /= MANT_BASE;
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for (i = 0; i < mant->n; i++) {
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carry += mant->digits[i] * factor;
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mant->digits[i] = carry % MANT_BASE;
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carry /= MANT_BASE;
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}
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if (carry) mant_append(mant, carry);
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}
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/* Divide the mantissa mant by a factor. Returns the remainder */
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static int32_t mant_div(struct Mant *mant, uint32_t divisor) {
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int32_t i;
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uint32_t quotient, remainder;
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uint64_t dividend;
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remainder = 0;
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for (i = mant->n - 1; i >= 0; i--) {
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dividend = ((uint64_t)remainder * MANT_BASE) + mant->digits[i];
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if (i < mant->n - 1) mant->digits[i + 1] = quotient;
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quotient = dividend / divisor;
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remainder = dividend % divisor;
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mant->digits[i] = remainder;
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}
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dividend = ((uint64_t)remainder * MANT_BASE) + mant->first_digit;
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if (mant->n) {
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if (mant->digits[mant->n - 1] == 0) mant->n--;
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}
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quotient = dividend / divisor;
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remainder = dividend % divisor;
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mant->first_digit = quotient;
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return remainder;
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}
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/* Shift left by a multiple of MANT_NBIT */
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static void mant_lshift_n(struct Mant *mant, int n) {
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if (!n) return;
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int32_t oldn = mant->n;
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mant_extra(mant, n);
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memmove(mant->digits + n, mant->digits, sizeof(uint32_t) * oldn);
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memset(mant->digits, 0, sizeof(uint32_t) * (n - 1));
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mant->digits[n - 1] = mant->first_digit;
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mant->first_digit = 0;
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}
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#ifdef __GNUC__
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#define clz(x) __builtin_clz(x)
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#else
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static int clz(uint32_t x) {
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int n = 0;
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if (x <= 0x0000ffff) n += 16, x <<= 16;
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if (x <= 0x00ffffff) n += 8, x <<= 8;
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if (x <= 0x0fffffff) n += 4, x <<= 4;
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if (x <= 0x3fffffff) n += 2, x <<= 2;
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if (x <= 0x7fffffff) n ++;
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return n;
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}
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#endif
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/* Extract double value from mantissa */
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static double mant_extract(struct Mant *mant, int32_t exponent2) {
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uint64_t top53;
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int32_t n = mant->n;
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/* Get most significant 52 bits from mant. Bit52 (0 indexed) should
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* always be 1. */
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if (n) {
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/* Two or more digits */
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uint64_t d1 = mant->digits[n - 1]; /* MSD (non-zero) */
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uint64_t d2 = (n == 1) ? mant->first_digit : mant->digits[n - 2];
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uint64_t d3 = (n > 2) ? mant->digits[n - 3] : (n == 2) ? mant->first_digit : 0;
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int lz = clz(d1);
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int nbits = 32 - lz;
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top53 = (d2 << (53 - MANT_NBIT)) + (d3 >> (2 * MANT_NBIT - 53));
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top53 >>= nbits;
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top53 |= (d1 << (53 - nbits));
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exponent2 += (nbits - 53) + MANT_NBIT * n;
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} else {
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/* One digit */
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top53 = mant->first_digit;
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}
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return ldexp((double) top53, exponent2);
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}
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/* Read in a mantissa and exponent of a certain base, and give
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* back the double value. Should properly handle 0s, Inifinties, and
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* back the double value. Should properly handle 0s, Infinities, and
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* denormalized numbers. (When the exponent values are too large) */
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static double convert(
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int negative,
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uint64_t mantissa,
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struct Mant *mant,
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int32_t base,
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int32_t exponent) {
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int32_t exponent2 = 0;
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/* Short circuit zero and huge numbers */
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if (mantissa == 0)
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if (mant->n == 0 && mant->first_digit == 0)
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return 0.0;
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if (exponent > 1022)
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return negative ? -INFINITY : INFINITY;
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/* TODO add fast paths */
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/* Final value is X = mant * base ^ exponent * 2 ^ exponent2
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* Get exponent to zero while holding X constant. */
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/* Convert exponent on the base into exponent2, the power of
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* 2 the will be used. Modify the mantissa as we convert. */
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if (exponent > 0) {
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/* Make the mantissa large enough so no precision is lost */
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while (mantissa <= 0x03ffffffffffffffULL && exponent > 0) {
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mantissa *= base;
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exponent--;
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/* Positive exponents are simple */
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while (exponent > 0) {
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mant_mul(mant, base);
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exponent--;
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}
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/* Negative exponents are tricky - we don't want to loose bits
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* from integer division, so we need to premultiply. */
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if (exponent < 0) {
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mant_lshift_n(mant, 10 - exponent);
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exponent2 -= (10 - exponent) * MANT_NBIT;
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while (exponent < -3) {
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mant_div(mant, (base * base) * (base * base));
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exponent += 4;
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}
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while (exponent > 0) {
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/* Allow 6 bits of room when multiplying. This is because
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* the largest base is 36, which is 6 bits. The space of 6 should
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* prevent overflow.*/
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mantissa >>= 1;
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exponent2++;
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if (mantissa <= 0x03ffffffffffffffULL) {
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mantissa *= base;
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exponent--;
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}
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}
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} else {
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while (exponent < 0) {
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mantissa <<= 1;
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exponent2--;
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/* Ensure that the last bit is set for minimum error
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* before dividing by the base */
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if (mantissa > 0x7fffffffffffffffULL) {
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mantissa /= base;
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exponent++;
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}
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mant_div(mant, base);
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exponent++;
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}
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}
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return negative
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? -ldexp((double) mantissa, exponent2)
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: ldexp((double) mantissa, exponent2);
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? -mant_extract(mant, exponent2)
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: mant_extract(mant, exponent2);
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}
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/* Result of scanning a number source string. Will be further processed
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* depending on the desired resultant type. */
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struct JanetScanRes {
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uint64_t mant;
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int32_t ex;
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int error;
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int base;
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int seenpoint;
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int foundexp;
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int neg;
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};
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/* Get the mantissa and exponent of decimal number. The
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* mantissa will be stored in a 64 bit unsigned integer (always positive).
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* The exponent will be in a signed 32 bit integer. Will also check if
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* the decimal point has been seen. Returns -1 if there is an invalid
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* number. */
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static struct JanetScanRes janet_scan_impl(
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/* Scan a real (double) from a string. If the string cannot be converted into
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* and integer, set *err to 1 and return 0. */
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double janet_scan_number(
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const uint8_t *str,
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int32_t len) {
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struct JanetScanRes res;
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int32_t len,
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int *err) {
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const uint8_t *end = str + len;
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/* Initialize flags */
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int seenadigit = 0;
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int gotradix = 0;
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/* Initialize result */
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res.mant = 0;
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res.ex = 0;
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res.error = 0;
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res.base = 10;
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res.seenpoint = 0;
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res.foundexp = 0;
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res.neg = 0;
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struct Mant mant = {0};
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int ex = 0;
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int base = 10;
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int seenpoint = 0;
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int foundexp = 0;
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int neg = 0;
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/* Prevent some kinds of overflow bugs relating to the exponent
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* overflowing. For example, if a string was passed 2GB worth of 0s after
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@ -168,18 +288,31 @@ static struct JanetScanRes janet_scan_impl(
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/* Get sign */
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if (str >= end) goto error;
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if (*str == '-') {
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res.neg = 1;
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neg = 1;
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str++;
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} else if (*str == '+') {
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str++;
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}
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/* Check for leading 0x or digit digit r */
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if (str + 1 < end && str[0] == '0' && str[1] == 'x') {
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base = 16;
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str += 2;
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} else if (str + 2 < end &&
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str[0] >= '0' && str[0] <= '9' &&
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str[1] >= '0' && str[1] <= '9' &&
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str[2] == 'r') {
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base = 10 * (str[0] - '0') + (str[1] - '0');
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if (base < 2 || base > 36) goto error;
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str += 3;
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}
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/* Skip leading zeros */
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while (str < end && (*str == '0' || *str == '.')) {
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if (res.seenpoint) res.ex--;
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if (seenpoint) ex--;
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if (*str == '.') {
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if (res.seenpoint) goto error;
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res.seenpoint = 1;
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if (seenpoint) goto error;
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seenpoint = 1;
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}
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seenadigit = 1;
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str++;
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@ -188,37 +321,21 @@ static struct JanetScanRes janet_scan_impl(
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/* Parse significant digits */
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while (str < end) {
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if (*str == '.') {
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if (res.seenpoint) goto error;
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res.seenpoint = 1;
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if (seenpoint) goto error;
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seenpoint = 1;
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} else if (*str == '&') {
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res.foundexp = 1;
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foundexp = 1;
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break;
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} else if (res.base == 10 && (*str == 'E' || *str == 'e')) {
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res.foundexp = 1;
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} else if (base == 10 && (*str == 'E' || *str == 'e')) {
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foundexp = 1;
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break;
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} else if (!gotradix && (*str == 'x' || *str == 'X')) {
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if (!seenadigit) goto error;
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if (res.seenpoint || res.mant > 0) goto error;
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res.base = 16;
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res.mant = 0;
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seenadigit = 0;
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gotradix = 1;
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} else if (!gotradix && (*str == 'r' || *str == 'R')) {
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if (res.seenpoint) goto error;
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if (res.mant < 2 || res.mant > 36) goto error;
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res.base = (int) res.mant;
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res.mant = 0;
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seenadigit = 0;
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gotradix = 1;
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} else if (*str != '_') {
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/* underscores are ignored - can be used for separator */
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int digit = digit_lookup[*str & 0x7F];
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if (*str > 127 || digit >= res.base) goto error;
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if (res.seenpoint) res.ex--;
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if (res.mant > 0x00ffffffffffffff)
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res.ex++;
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else
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res.mant = res.base * res.mant + digit;
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if (*str > 127 || digit >= base) goto error;
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if (seenpoint) ex--;
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mant_mul(&mant, base);
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mant_add(&mant, digit);
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seenadigit = 1;
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}
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str++;
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@ -228,7 +345,7 @@ static struct JanetScanRes janet_scan_impl(
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goto error;
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/* Read exponent */
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if (str < end && res.foundexp) {
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if (str < end && foundexp) {
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int eneg = 0;
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int ee = 0;
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seenadigit = 0;
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@ -241,72 +358,33 @@ static struct JanetScanRes janet_scan_impl(
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str++;
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}
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/* Skip leading 0s in exponent */
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while (str < end && *str == '0') str++;
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while (str < end && *str == '0') {
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str++;
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seenadigit = 1;
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}
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while (str < end && ee < (INT32_MAX / 40)) {
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int digit = digit_lookup[*str & 0x7F];
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if (*str == '_') {
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str++;
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continue;
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}
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if (*str > 127 || digit >= res.base) goto error;
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ee = res.base * ee + digit;
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if (*str > 127 || digit >= base) goto error;
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ee = base * ee + digit;
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str++;
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seenadigit = 1;
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}
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if (eneg) res.ex -= ee; else res.ex += ee;
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if (eneg) ex -= ee; else ex += ee;
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}
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if (!seenadigit)
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goto error;
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return res;
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double result = convert(neg, &mant, base, ex);
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free(mant.digits);
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return result;
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error:
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res.error = 1;
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return res;
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}
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/* Scan an integer from a string. If the string cannot be converted into
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* and integer, set *err to 1 and return 0. */
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int32_t janet_scan_integer(
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const uint8_t *str,
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int32_t len,
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int *err) {
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struct JanetScanRes res = janet_scan_impl(str, len);
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int64_t i64;
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if (res.error) goto error;
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if (res.seenpoint) goto error;
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if (res.ex < 0) goto error;
|
||||
i64 = res.neg ? -(int64_t)res.mant : (int64_t)res.mant;
|
||||
while (res.ex > 0) {
|
||||
i64 *= res.base;
|
||||
if (i64 > INT32_MAX || i64 < INT32_MIN) goto error;
|
||||
res.ex--;
|
||||
}
|
||||
if (i64 > INT32_MAX || i64 < INT32_MIN) goto error;
|
||||
if (NULL != err)
|
||||
*err = 0;
|
||||
return (int32_t) i64;
|
||||
error:
|
||||
if (NULL != err)
|
||||
*err = 1;
|
||||
return 0;
|
||||
}
|
||||
|
||||
/* Scan a real (double) from a string. If the string cannot be converted into
|
||||
* and integer, set *err to 1 and return 0. */
|
||||
double janet_scan_number(
|
||||
const uint8_t *str,
|
||||
int32_t len,
|
||||
int *err) {
|
||||
struct JanetScanRes res = janet_scan_impl(str, len);
|
||||
if (res.error) {
|
||||
if (NULL != err)
|
||||
*err = 1;
|
||||
return 0.0;
|
||||
} else {
|
||||
if (NULL != err)
|
||||
*err = 0;
|
||||
}
|
||||
return convert(res.neg, res.mant, res.base, res.ex);
|
||||
*err = 1;
|
||||
free(mant.digits);
|
||||
return 0.0;
|
||||
}
|
||||
|
||||
@ -915,7 +915,6 @@ JANET_API int janet_dobytes(JanetTable *env, const uint8_t *bytes, int32_t len,
|
||||
JANET_API int janet_dostring(JanetTable *env, const char *str, const char *sourcePath, Janet *out);
|
||||
|
||||
/* Number scanning */
|
||||
JANET_API int32_t janet_scan_integer(const uint8_t *str, int32_t len, int *err);
|
||||
JANET_API double janet_scan_number(const uint8_t *str, int32_t len, int *err);
|
||||
|
||||
/* Debugging */
|
||||
|
||||
Loading…
Reference in New Issue
Block a user