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>
82 lines
3.1 KiB
C
82 lines
3.1 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_MPPRINT_H
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#define MICROPY_INCLUDED_PY_MPPRINT_H
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#include "py/mpconfig.h"
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#define PF_FLAG_LEFT_ADJUST (0x001)
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#define PF_FLAG_SHOW_SIGN (0x002)
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#define PF_FLAG_SPACE_SIGN (0x004)
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#define PF_FLAG_SHOW_PREFIX (0x008)
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#define PF_FLAG_PAD_AFTER_SIGN (0x010)
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#define PF_FLAG_CENTER_ADJUST (0x020)
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#define PF_FLAG_ADD_PERCENT (0x040)
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#define PF_FLAG_SHOW_OCTAL_LETTER (0x080)
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#define PF_FLAG_ALWAYS_DECIMAL (0x100)
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#define PF_FLAG_SEP_POS (9) // must be above all the above PF_FLAGs
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#if MICROPY_PY_IO && MICROPY_PY_SYS_STDFILES
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#define MP_PYTHON_PRINTER &mp_sys_stdout_print
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#else
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#define MP_PYTHON_PRINTER &mp_plat_print
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#endif
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typedef void (*mp_print_strn_t)(void *data, const char *str, size_t len);
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typedef struct _mp_print_t {
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void *data;
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mp_print_strn_t print_strn;
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} mp_print_t;
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typedef struct _mp_print_ext_t {
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mp_print_t base;
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const char *item_separator;
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const char *key_separator;
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} mp_print_ext_t;
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#define MP_PRINT_GET_EXT(print) ((mp_print_ext_t *)print)
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// All (non-debug) prints go through one of the two interfaces below.
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// 1) Wrapper for platform print function, which wraps MP_PLAT_PRINT_STRN.
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extern const mp_print_t mp_plat_print;
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#if MICROPY_PY_IO && MICROPY_PY_SYS_STDFILES
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// 2) Wrapper for printing to sys.stdout.
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extern const mp_print_t mp_sys_stdout_print;
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#endif
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int mp_print_str(const mp_print_t *print, const char *str);
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int mp_print_strn(const mp_print_t *print, const char *str, size_t len, unsigned int flags, char fill, int width);
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#if MICROPY_PY_BUILTINS_FLOAT
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int mp_print_float(const mp_print_t *print, mp_float_t f, char fmt, unsigned int flags, char fill, int width, int prec);
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#endif
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int mp_printf(const mp_print_t *print, const char *fmt, ...);
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#ifdef va_start
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int mp_vprintf(const mp_print_t *print, const char *fmt, va_list args);
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#endif
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#endif // MICROPY_INCLUDED_PY_MPPRINT_H
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