dbbaa959c8
Following discussions in PR #16666, this commit updates the float formatting code to improve the `repr` reversibility, i.e. the percentage of valid floating point numbers that do parse back to the same number when formatted by `repr` (in CPython it's 100%). This new code offers a choice of 3 float conversion methods, depending on the desired tradeoff between code size and conversion precision: - BASIC method is the smallest code footprint - APPROX method uses an iterative method to approximate the exact representation, which is a bit slower but but does not have a big impact on code size. It provides `repr` reversibility on >99.8% of the cases in double precision, and on >98.5% in single precision (except with REPR_C, where reversibility is 100% as the last two bits are not taken into account). - EXACT method uses higher-precision floats during conversion, which provides perfect results but has a higher impact on code size. It is faster than APPROX method, and faster than the CPython equivalent implementation. It is however not available on all compilers when using FLOAT_IMPL_DOUBLE. Here is the table comparing the impact of the three conversion methods on code footprint on PYBV10 (using single-precision floats) and reversibility rate for both single-precision and double-precision floats. The table includes current situation as a baseline for the comparison: PYBV10 REPR_C FLOAT DOUBLE current = 364688 12.9% 27.6% 37.9% basic = 364812 85.6% 60.5% 85.7% approx = 365080 100.0% 98.5% 99.8% exact = 366408 100.0% 100.0% 100.0% Signed-off-by: Yoctopuce dev <dev@yoctopuce.com>
56 lines
2.3 KiB
C
56 lines
2.3 KiB
C
/*
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* This file is part of the MicroPython project, http://micropython.org/
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*
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* The MIT License (MIT)
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*
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* Copyright (c) 2013, 2014 Damien P. George
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#ifndef MICROPY_INCLUDED_PY_PARSENUM_H
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#define MICROPY_INCLUDED_PY_PARSENUM_H
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#include "py/mpconfig.h"
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#include "py/lexer.h"
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#include "py/obj.h"
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// these functions raise a SyntaxError if lex!=NULL, else a ValueError
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mp_obj_t mp_parse_num_integer(const char *restrict str, size_t len, int base, mp_lexer_t *lex);
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#if MICROPY_PY_BUILTINS_FLOAT
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mp_large_float_t mp_decimal_exp(mp_large_float_t num, int dec_exp);
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const char *mp_parse_float_internal(const char *str, size_t len, mp_float_t *res);
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#endif
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#if MICROPY_PY_BUILTINS_COMPLEX
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mp_obj_t mp_parse_num_decimal(const char *str, size_t len, bool allow_imag, bool force_complex, mp_lexer_t *lex);
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static inline mp_obj_t mp_parse_num_float(const char *str, size_t len, bool allow_imag, mp_lexer_t *lex) {
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return mp_parse_num_decimal(str, len, allow_imag, false, lex);
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}
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static inline mp_obj_t mp_parse_num_complex(const char *str, size_t len, mp_lexer_t *lex) {
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return mp_parse_num_decimal(str, len, true, true, lex);
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}
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#else
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mp_obj_t mp_parse_num_float(const char *str, size_t len, bool allow_imag, mp_lexer_t *lex);
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#endif
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#endif // MICROPY_INCLUDED_PY_PARSENUM_H
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