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-rw-r--r--py/parsenum.c211
-rw-r--r--py/parsenum.h5
2 files changed, 117 insertions, 99 deletions
diff --git a/py/parsenum.c b/py/parsenum.c
index fcc690917..019491b51 100644
--- a/py/parsenum.c
+++ b/py/parsenum.c
@@ -195,6 +195,8 @@ value_error:
}
}
+#if MICROPY_PY_BUILTINS_FLOAT
+
enum {
REAL_IMAG_STATE_START = 0,
REAL_IMAG_STATE_HAVE_REAL = 1,
@@ -207,25 +209,39 @@ typedef enum {
PARSE_DEC_IN_EXP,
} parse_dec_in_t;
-#if MICROPY_PY_BUILTINS_FLOAT
// MANTISSA_MAX is used to retain precision while not overflowing mantissa
-// SMALL_NORMAL_VAL is the smallest power of 10 that is still a normal float
-// EXACT_POWER_OF_10 is the largest value of x so that 10^x can be stored exactly in a float
-// Note: EXACT_POWER_OF_10 is at least floor(log_5(2^mantissa_length)). Indeed, 10^n = 2^n * 5^n
-// so we only have to store the 5^n part in the mantissa (the 2^n part will go into the float's
-// exponent).
+#define MANTISSA_MAX (sizeof(mp_float_uint_t) == 8 ? 0x1999999999999998ULL : 0x19999998U)
+
+// MAX_EXACT_POWER_OF_5 is the largest value of x so that 5^x can be stored exactly in a float
#if MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT
-#define MANTISSA_MAX 0x19999998U
-#define SMALL_NORMAL_VAL (1e-37F)
-#define SMALL_NORMAL_EXP (-37)
-#define EXACT_POWER_OF_10 (9)
+#define MAX_EXACT_POWER_OF_5 (10)
#elif MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_DOUBLE
-#define MANTISSA_MAX 0x1999999999999998ULL
-#define SMALL_NORMAL_VAL (1e-307)
-#define SMALL_NORMAL_EXP (-307)
-#define EXACT_POWER_OF_10 (22)
+#define MAX_EXACT_POWER_OF_5 (22)
#endif
+// Helper to compute `num * (10.0 ** dec_exp)`
+mp_float_t mp_decimal_exp(mp_float_t num, int dec_exp) {
+
+ if (dec_exp == 0 || num == MICROPY_FLOAT_CONST(0.0)) {
+ return num;
+ }
+ mp_float_union_t res = {num};
+ // Multiply first by (2.0 ** dec_exp) via the exponent
+ // - this will ensure that the result of `pow()` is always in mp_float_t range
+ // when the result is expected to be in mp_float_t range (e.g. during format)
+ // - we don't need to care about p.exp overflow, as (5.0 ** dec_exp) will anyway
+ // force the final result toward the proper edge if needed (0.0 or inf)
+ res.p.exp += dec_exp;
+ // Use positive exponents when they are more precise then negative
+ if (dec_exp < 0 && dec_exp >= -MAX_EXACT_POWER_OF_5) {
+ res.f /= MICROPY_FLOAT_C_FUN(pow)(5, -dec_exp);
+ } else {
+ res.f *= MICROPY_FLOAT_C_FUN(pow)(5, dec_exp);
+ }
+ return (mp_float_t)res.f;
+}
+
+
// Break out inner digit accumulation routine to ease trailing zero deferral.
static mp_float_uint_t accept_digit(mp_float_uint_t p_mantissa, unsigned int dig, int *p_exp_extra, int in) {
// Core routine to ingest an additional digit.
@@ -244,6 +260,85 @@ static mp_float_uint_t accept_digit(mp_float_uint_t p_mantissa, unsigned int dig
return p_mantissa;
}
}
+
+// Helper to parse an unsigned decimal number into a mp_float_t
+const char *mp_parse_float_internal(const char *str, size_t len, mp_float_t *res) {
+ const char *top = str + len;
+
+ parse_dec_in_t in = PARSE_DEC_IN_INTG;
+ bool exp_neg = false;
+ mp_float_uint_t mantissa = 0;
+ int exp_val = 0;
+ int exp_extra = 0;
+ int trailing_zeros_intg = 0, trailing_zeros_frac = 0;
+ while (str < top) {
+ unsigned int dig = *str++;
+ if ('0' <= dig && dig <= '9') {
+ dig -= '0';
+ if (in == PARSE_DEC_IN_EXP) {
+ // don't overflow exp_val when adding next digit, instead just truncate
+ // it and the resulting float will still be correct, either inf or 0.0
+ // (use INT_MAX/2 to allow adding exp_extra at the end without overflow)
+ if (exp_val < (INT_MAX / 2 - 9) / 10) {
+ exp_val = 10 * exp_val + dig;
+ }
+ } else {
+ if (dig == 0 || mantissa >= MANTISSA_MAX) {
+ // Defer treatment of zeros in fractional part. If nothing comes afterwards, ignore them.
+ // Also, once we reach MANTISSA_MAX, treat every additional digit as a trailing zero.
+ if (in == PARSE_DEC_IN_INTG) {
+ ++trailing_zeros_intg;
+ } else {
+ ++trailing_zeros_frac;
+ }
+ } else {
+ // Time to un-defer any trailing zeros. Intg zeros first.
+ while (trailing_zeros_intg) {
+ mantissa = accept_digit(mantissa, 0, &exp_extra, PARSE_DEC_IN_INTG);
+ --trailing_zeros_intg;
+ }
+ while (trailing_zeros_frac) {
+ mantissa = accept_digit(mantissa, 0, &exp_extra, PARSE_DEC_IN_FRAC);
+ --trailing_zeros_frac;
+ }
+ mantissa = accept_digit(mantissa, dig, &exp_extra, in);
+ }
+ }
+ } else if (in == PARSE_DEC_IN_INTG && dig == '.') {
+ in = PARSE_DEC_IN_FRAC;
+ } else if (in != PARSE_DEC_IN_EXP && ((dig | 0x20) == 'e')) {
+ in = PARSE_DEC_IN_EXP;
+ if (str < top) {
+ if (str[0] == '+') {
+ str++;
+ } else if (str[0] == '-') {
+ str++;
+ exp_neg = true;
+ }
+ }
+ if (str == top) {
+ return NULL;
+ }
+ } else if (dig == '_') {
+ continue;
+ } else {
+ // unknown character
+ str--;
+ break;
+ }
+ }
+
+ // work out the exponent
+ if (exp_neg) {
+ exp_val = -exp_val;
+ }
+ exp_val += exp_extra + trailing_zeros_intg;
+
+ // At this point, we just need to multiply the mantissa by its base 10 exponent.
+ *res = (mp_float_t)mp_decimal_exp(mantissa, exp_val);
+
+ return str;
+}
#endif // MICROPY_PY_BUILTINS_FLOAT
#if MICROPY_PY_BUILTINS_COMPLEX
@@ -295,91 +390,9 @@ parse_start:;
dec_val = MICROPY_FLOAT_C_FUN(nan)("");
} else {
// string should be a decimal number
- parse_dec_in_t in = PARSE_DEC_IN_INTG;
- bool exp_neg = false;
- mp_float_uint_t mantissa = 0;
- int exp_val = 0;
- int exp_extra = 0;
- int trailing_zeros_intg = 0, trailing_zeros_frac = 0;
- while (str < top) {
- unsigned int dig = *str++;
- if ('0' <= dig && dig <= '9') {
- dig -= '0';
- if (in == PARSE_DEC_IN_EXP) {
- // don't overflow exp_val when adding next digit, instead just truncate
- // it and the resulting float will still be correct, either inf or 0.0
- // (use INT_MAX/2 to allow adding exp_extra at the end without overflow)
- if (exp_val < (INT_MAX / 2 - 9) / 10) {
- exp_val = 10 * exp_val + dig;
- }
- } else {
- if (dig == 0 || mantissa >= MANTISSA_MAX) {
- // Defer treatment of zeros in fractional part. If nothing comes afterwards, ignore them.
- // Also, once we reach MANTISSA_MAX, treat every additional digit as a trailing zero.
- if (in == PARSE_DEC_IN_INTG) {
- ++trailing_zeros_intg;
- } else {
- ++trailing_zeros_frac;
- }
- } else {
- // Time to un-defer any trailing zeros. Intg zeros first.
- while (trailing_zeros_intg) {
- mantissa = accept_digit(mantissa, 0, &exp_extra, PARSE_DEC_IN_INTG);
- --trailing_zeros_intg;
- }
- while (trailing_zeros_frac) {
- mantissa = accept_digit(mantissa, 0, &exp_extra, PARSE_DEC_IN_FRAC);
- --trailing_zeros_frac;
- }
- mantissa = accept_digit(mantissa, dig, &exp_extra, in);
- }
- }
- } else if (in == PARSE_DEC_IN_INTG && dig == '.') {
- in = PARSE_DEC_IN_FRAC;
- } else if (in != PARSE_DEC_IN_EXP && ((dig | 0x20) == 'e')) {
- in = PARSE_DEC_IN_EXP;
- if (str < top) {
- if (str[0] == '+') {
- str++;
- } else if (str[0] == '-') {
- str++;
- exp_neg = true;
- }
- }
- if (str == top) {
- goto value_error;
- }
- } else if (dig == '_') {
- continue;
- } else {
- // unknown character
- str--;
- break;
- }
- }
-
- // work out the exponent
- if (exp_neg) {
- exp_val = -exp_val;
- }
-
- // apply the exponent, making sure it's not a subnormal value
- exp_val += exp_extra + trailing_zeros_intg;
- dec_val = (mp_float_t)mantissa;
- if (exp_val < SMALL_NORMAL_EXP) {
- exp_val -= SMALL_NORMAL_EXP;
- dec_val *= SMALL_NORMAL_VAL;
- }
-
- // At this point, we need to multiply the mantissa by its base 10 exponent. If possible,
- // we would rather manipulate numbers that have an exact representation in IEEE754. It
- // turns out small positive powers of 10 do, whereas small negative powers of 10 don't.
- // So in that case, we'll yield a division of exact values rather than a multiplication
- // of slightly erroneous values.
- if (exp_val < 0 && exp_val >= -EXACT_POWER_OF_10) {
- dec_val /= MICROPY_FLOAT_C_FUN(pow)(10, -exp_val);
- } else {
- dec_val *= MICROPY_FLOAT_C_FUN(pow)(10, exp_val);
+ str = mp_parse_float_internal(str, top - str, &dec_val);
+ if (!str) {
+ goto value_error;
}
}
diff --git a/py/parsenum.h b/py/parsenum.h
index f444632d2..a807cb09d 100644
--- a/py/parsenum.h
+++ b/py/parsenum.h
@@ -34,6 +34,11 @@
mp_obj_t mp_parse_num_integer(const char *restrict str, size_t len, int base, mp_lexer_t *lex);
+#if MICROPY_PY_BUILTINS_FLOAT
+mp_float_t mp_decimal_exp(mp_float_t num, int dec_exp);
+const char *mp_parse_float_internal(const char *str, size_t len, mp_float_t *res);
+#endif
+
#if MICROPY_PY_BUILTINS_COMPLEX
mp_obj_t mp_parse_num_decimal(const char *str, size_t len, bool allow_imag, bool force_complex, mp_lexer_t *lex);
generated by cgit v1.2.3 (git 2.46.0) at 2025-11-10 21:54:27 +0000