/** * @author (c) Eyal Rozenberg * 2021-2022, Haifa, Palestine/Israel * @author (c) Marco Paland (info@paland.com) * 2014-2019, PALANDesign Hannover, Germany * * @note Others have made smaller contributions to this file: see the * contributors page at https://github.com/eyalroz/printf/graphs/contributors * or ask one of the authors. The original code for exponential specifiers was * contributed by Martijn Jasperse . * * @brief Small stand-alone implementation of the printf family of functions * (`(v)printf`, `(v)s(n)printf` etc., geared towards use on embedded systems with * a very limited resources. * * @note the implementations are thread-safe; re-entrant; use no functions from * the standard library; and do not dynamically allocate any memory. * * @license The MIT License (MIT) * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ #include #include #include #include #include "vlibc_stdio.h" #define _VLIBC_IO_HAVE_WRITE ((unsigned char)(0x04)) #define _VLIBC_IO_HAVE_READ ((unsigned char)(0x08)) #define _VLIBC_IO_VBUF_MASK ((unsigned char)(0x60)) #define _VLIBC_IO_VBUF_FBF ((unsigned char)(0x40)) #define _VLIBC_IO_VBUF_LBF ((unsigned char)(0x20)) #define _VLIBC_IO_VBUF_NBF ((unsigned char)(0x00)) #define _VLIBC_IO_AUTO_BUFF ((unsigned char)(0x80)) #define _VLIBC_TYPEIS_IO ((int)(0x01)) #define _VLIBC_TYPEIS_FILE ((int)(0x02)) #ifdef CONFIG_VLIBC_DEBUG #define CHECK_FILE(_stream, __ret) \ do { \ if ((void *)(_stream) == NULL) { \ errno = EINVAL; \ return __ret; \ } \ } while (0) #else #define CHECK_FILE(_stream, __ret) \ do { \ } while (0) #endif #define vlibc_file(_stream) ((vlibc_file_t *)(_stream)) #define IF_IO_DEV(_stream) \ if (((vlibc_file(_stream)->magic) & _VLIBC_MAGIC_MASK) == _VLIBC_IO_MAGIC_CODE) #define IF_FILE(_stream) \ if (((vlibc_file(_stream)->magic) & _VLIBC_MAGIC_MASK) == _VLIBC_FILE_MAGIC_CODE) #ifdef CONFIG_VLIBC_FATFS extern int FRESULT_to_errno[20]; #endif /** @addtogroup config ******************************************************** * @{ */ // 'ntoa' conversion buffer size, this must be big enough to hold one converted // numeric number including padded zeros (dynamically created on stack) #ifndef PRINTF_INTEGER_BUFFER_SIZE #define PRINTF_INTEGER_BUFFER_SIZE 32 #endif // size of the fixed (on-stack) buffer for printing individual decimal numbers. // this must be big enough to hold one converted floating-point value including // padded zeros. #ifndef PRINTF_DECIMAL_BUFFER_SIZE #define PRINTF_DECIMAL_BUFFER_SIZE 32 #endif // Support for the decimal notation floating point conversion specifiers (%f, %F) #ifndef CONFIG_VLIBC_FLOAT #define CONFIG_VLIBC_FLOAT 1 #endif // Support for the exponential notation floating point conversion specifiers (%e, %g, %E, %G) #ifndef CONFIG_VLIBC_FLOAT_EX #define CONFIG_VLIBC_FLOAT_EX 0 #endif // Support for the length write-back specifier (%n) #ifndef CONFIG_VLIBC_WRITEBACK #define CONFIG_VLIBC_WRITEBACK 0 #endif // Default precision for the floating point conversion specifiers (the C standard sets this at 6) #ifndef VLIBC_DEFAULT_FLOAT_PRECISION #define VLIBC_DEFAULT_FLOAT_PRECISION 6 #endif // According to the C languages standard, printf() and related functions must be able to print any // integral number in floating-point notation, regardless of length, when using the %f specifier - // possibly hundreds of characters, potentially overflowing your buffers. In this implementation, // all values beyond this threshold are switched to exponential notation. #ifndef VLIBC_MAX_INTEGRAL_DIGITS_FOR_DECIMAL #define VLIBC_MAX_INTEGRAL_DIGITS_FOR_DECIMAL 9 #endif // Support for the long long integral types (with the ll, z and t length modifiers for specifiers // %d,%i,%o,%x,%X,%u, and with the %p specifier). Note: 'L' (long double) is not supported. #ifndef CONFIG_VLIBC_LONG_LONG #define CONFIG_VLIBC_LONG_LONG 0 #endif // The number of terms in a Taylor series expansion of log_10(x) to // use for approximation - including the power-zero term (i.e. the // value at the point of expansion). #ifndef PRINTF_LOG10_TAYLOR_TERMS #define PRINTF_LOG10_TAYLOR_TERMS 4 #endif #if PRINTF_LOG10_TAYLOR_TERMS <= 1 #error "At least one non-constant Taylor expansion is necessary for the log10() calculation" #endif #define PRINTF_PREFER_DECIMAL false #define PRINTF_PREFER_EXPONENTIAL true /****************************************************************************** * @} */ // The following will convert the number-of-digits into an exponential-notation literal #define PRINTF_CONCATENATE(s1, s2) s1##s2 #define PRINTF_EXPAND_THEN_CONCATENATE(s1, s2) PRINTF_CONCATENATE(s1, s2) #define PRINTF_FLOAT_NOTATION_THRESHOLD PRINTF_EXPAND_THEN_CONCATENATE(1e, VLIBC_MAX_INTEGRAL_DIGITS_FOR_DECIMAL) // internal flag definitions #define FLAGS_ZEROPAD (1U << 0U) #define FLAGS_LEFT (1U << 1U) #define FLAGS_PLUS (1U << 2U) #define FLAGS_SPACE (1U << 3U) #define FLAGS_HASH (1U << 4U) #define FLAGS_UPPERCASE (1U << 5U) #define FLAGS_CHAR (1U << 6U) #define FLAGS_SHORT (1U << 7U) #define FLAGS_INT (1U << 8U) #define FLAGS_LONG (1U << 9U) #define FLAGS_LONG_LONG (1U << 10U) #define FLAGS_PRECISION (1U << 11U) #define FLAGS_ADAPT_EXP (1U << 12U) #define FLAGS_POINTER (1U << 13U) // Note: Similar, but not identical, effect as FLAGS_HASH #define FLAGS_SIGNED (1U << 14U) typedef unsigned int printf_flags_t; #define BASE_BINARY 2 #define BASE_OCTAL 8 #define BASE_DECIMAL 10 #define BASE_HEX 16 typedef uint8_t numeric_base_t; #if CONFIG_VLIBC_LONG_LONG typedef unsigned long long printf_unsigned_value_t; typedef long long printf_signed_value_t; #else typedef unsigned long printf_unsigned_value_t; typedef long printf_signed_value_t; #endif #define PRINTF_MAX_POSSIBLE_BUFFER_SIZE INT_MAX // If we were to nitpick, this would actually be INT_MAX + 1, // since INT_MAX is the maximum return value, which excludes the // trailing '\0'. #if (CONFIG_VLIBC_FLOAT || CONFIG_VLIBC_FLOAT_EX) #include #if FLT_RADIX != 2 #error "Non-binary-radix floating-point types are unsupported." #endif #if DBL_MANT_DIG == 24 #define DOUBLE_SIZE_IN_BITS 32 typedef uint32_t double_uint_t; #define DOUBLE_EXPONENT_MASK 0xFFU #define DOUBLE_BASE_EXPONENT 127 #define DOUBLE_MAX_SUBNORMAL_EXPONENT_OF_10 -38 #define DOUBLE_MAX_SUBNORMAL_POWER_OF_10 1e-38 #elif DBL_MANT_DIG == 53 #define DOUBLE_SIZE_IN_BITS 64 typedef uint64_t double_uint_t; #define DOUBLE_EXPONENT_MASK 0x7FFU #define DOUBLE_BASE_EXPONENT 1023 #define DOUBLE_MAX_SUBNORMAL_EXPONENT_OF_10 -308 #define DOUBLE_MAX_SUBNORMAL_POWER_OF_10 1e-308 #else #error "Unsupported double type configuration" #endif #define DOUBLE_STORED_MANTISSA_BITS (DBL_MANT_DIG - 1) typedef union { double_uint_t U; double F; } double_with_bit_access; // This is unnecessary in C99, since compound initializers can be used, // but: // 1. Some compilers are finicky about this; // 2. Some people may want to convert this to C89; // 3. If you try to use it as C++, only C++20 supports compound literals static inline double_with_bit_access get_bit_access(double x) { double_with_bit_access dwba; dwba.F = x; return dwba; } static inline int get_sign_bit(double x) { // The sign is stored in the highest bit return (int)(get_bit_access(x).U >> (DOUBLE_SIZE_IN_BITS - 1)); } static inline int get_exp2(double_with_bit_access x) { // The exponent in an IEEE-754 floating-point number occupies a contiguous // sequence of bits (e.g. 52..62 for 64-bit doubles), but with a non-trivial representation: An // unsigned offset from some negative value (with the extremal offset values reserved for // special use). return (int)((x.U >> DOUBLE_STORED_MANTISSA_BITS) & DOUBLE_EXPONENT_MASK) - DOUBLE_BASE_EXPONENT; } #define PRINTF_ABS(_x) ((_x) > 0 ? (_x) : -(_x)) #endif // (CONFIG_VLIBC_FLOAT || CONFIG_VLIBC_FLOAT_EX) // Note in particular the behavior here on LONG_MIN or LLONG_MIN; it is valid // and well-defined, but if you're not careful you can easily trigger undefined // behavior with -LONG_MIN or -LLONG_MIN #define ABS_FOR_PRINTING(_x) ((printf_unsigned_value_t)((_x) > 0 ? (_x) : -((printf_signed_value_t)_x))) // wrapper (used as buffer) for output function type // // One of the following must hold: // 1. max is 0 // 2. buffer is non-null // 3. stream is non-null // // ... otherwise bad things will happen. typedef struct { VLIBC_FILE *stream; char *buffer; size_t pos; size_t max; } output_gadget_t; /** @addtogroup putc functions * @{ */ static inline void putc_via_buffer(output_gadget_t *output, char c) { size_t write_pos = output->pos++; if (write_pos >= output->max) { return; } output->buffer[write_pos] = c; } static inline void putc_via_file(output_gadget_t *output, char c) { size_t write_pos = output->max++; output->pos++; if (write_pos >= VLIBC_FBUFSIZ) { output->max = 0; write_pos = 0; #ifdef CONFIG_VLIBC_FATFS FRESULT fresult; size_t bytes; fresult = f_write(output->stream->file, output->buffer, VLIBC_FBUFSIZ, &bytes); if (fresult != FR_OK) { if (fresult <= FR_INVALID_PARAMETER) { errno = FRESULT_to_errno[fresult]; } } #else #endif } output->buffer[write_pos] = c; return; } static inline void putc_via_iodev_nbf(output_gadget_t *output, char c) { output->pos++; if (__vlibc_io_mem2dev(output->stream->io, &c, 1) == 0) { errno = EINVAL; } } static inline void putc_via_iodev_lbf(output_gadget_t *output, char c) { register char *bg = output->stream->io->bg; register char *wp = output->stream->io->wp; register char *ed = output->stream->io->ed; output->pos++; *wp++ = c; if ((c == '\n') || (wp == ed)) { if (__vlibc_io_mem2dev(output->stream->io, bg, wp - bg) == 0) { errno = EINVAL; goto done; } wp = bg; } done: output->stream->io->wp = wp; } static inline void putc_via_iodev_fbf(output_gadget_t *output, char c) { register char *bg = output->stream->io->bg; register char *wp = output->stream->io->wp; register char *ed = output->stream->io->ed; output->pos++; *wp++ = c; if (wp == ed) { if (__vlibc_io_mem2dev(output->stream->io, bg, ed - bg) == 0) { errno = EINVAL; goto done; } wp = bg; } done: output->stream->io->wp = wp; } /** * @} */ /** @addtogroup internal std c functions * @{ */ // internal secure strlen // @return The length of the string (excluding the terminating 0) limited by 'maxsize' // @note strlen uses size_t, but wes only use this function with size_t // variables - hence the signature. static inline size_t strnlen_s_(const char *str, size_t maxsize) { const char *s; for (s = str; *s && maxsize--; ++s) ; return (size_t)(s - str); } // internal test if char is a digit (0-9) // @return true if char is a digit static inline bool is_digit_(char ch) { return (ch >= '0') && (ch <= '9'); } // internal ASCII string to size_t conversion static size_t atou_(const char **str) { size_t i = 0U; while (is_digit_(**str)) { i = i * 10U + (size_t)(*((*str)++) - '0'); } return i; } /** * @} */ // output the specified string in reverse, taking care of any zero-padding static void out_rev_(output_gadget_t *output, void (*putc_function)(output_gadget_t *, char), const char *buf, size_t len, size_t width, printf_flags_t flags) { const size_t start_pos = output->pos; // pad spaces up to given width if (!(flags & FLAGS_LEFT) && !(flags & FLAGS_ZEROPAD)) { for (size_t i = len; i < width; i++) { putc_function(output, ' '); } } // reverse string while (len) { putc_function(output, buf[--len]); } // append pad spaces up to given width if (flags & FLAGS_LEFT) { while (output->pos - start_pos < width) { putc_function(output, ' '); } } } // Invoked by print_integer after the actual number has been printed, performing necessary // work on the number's prefix (as the number is initially printed in reverse order) static void print_integer_finalization(output_gadget_t *output, void (*putc_function)(output_gadget_t *, char), char *buf, size_t len, bool negative, numeric_base_t base, size_t precision, size_t width, printf_flags_t flags) { size_t unpadded_len = len; // pad with leading zeros { if (!(flags & FLAGS_LEFT)) { if (width && (flags & FLAGS_ZEROPAD) && (negative || (flags & (FLAGS_PLUS | FLAGS_SPACE)))) { width--; } while ((flags & FLAGS_ZEROPAD) && (len < width) && (len < PRINTF_INTEGER_BUFFER_SIZE)) { buf[len++] = '0'; } } while ((len < precision) && (len < PRINTF_INTEGER_BUFFER_SIZE)) { buf[len++] = '0'; } if (base == BASE_OCTAL && (len > unpadded_len)) { // Since we've written some zeros, we've satisfied the alternative format leading space requirement flags &= ~FLAGS_HASH; } } // handle hash if (flags & (FLAGS_HASH | FLAGS_POINTER)) { if (!(flags & FLAGS_PRECISION) && len && ((len == precision) || (len == width))) { // Let's take back some padding digits to fit in what will eventually // be the format-specific prefix if (unpadded_len < len) { len--; // This should suffice for BASE_OCTAL } if (len && (base == BASE_HEX || base == BASE_BINARY) && (unpadded_len < len)) { len--; // ... and an extra one for 0x or 0b } } if ((base == BASE_HEX) && !(flags & FLAGS_UPPERCASE) && (len < PRINTF_INTEGER_BUFFER_SIZE)) { buf[len++] = 'x'; } else if ((base == BASE_HEX) && (flags & FLAGS_UPPERCASE) && (len < PRINTF_INTEGER_BUFFER_SIZE)) { buf[len++] = 'X'; } else if ((base == BASE_BINARY) && (len < PRINTF_INTEGER_BUFFER_SIZE)) { buf[len++] = 'b'; } if (len < PRINTF_INTEGER_BUFFER_SIZE) { buf[len++] = '0'; } } if (len < PRINTF_INTEGER_BUFFER_SIZE) { if (negative) { buf[len++] = '-'; } else if (flags & FLAGS_PLUS) { buf[len++] = '+'; // ignore the space if the '+' exists } else if (flags & FLAGS_SPACE) { buf[len++] = ' '; } } out_rev_(output, putc_function, buf, len, width, flags); } // An internal itoa-like function static void print_integer(output_gadget_t *output, void (*putc_function)(output_gadget_t *, char), printf_unsigned_value_t value, bool negative, numeric_base_t base, size_t precision, size_t width, printf_flags_t flags) { char buf[PRINTF_INTEGER_BUFFER_SIZE]; size_t len = 0U; if (!value) { if (!(flags & FLAGS_PRECISION)) { buf[len++] = '0'; flags &= ~FLAGS_HASH; // We drop this flag this since either the alternative and regular modes of the specifier // don't differ on 0 values, or (in the case of octal) we've already provided the special // handling for this mode. } else if (base == BASE_HEX) { flags &= ~FLAGS_HASH; // We drop this flag this since either the alternative and regular modes of the specifier // don't differ on 0 values } } else { do { const char digit = (char)(value % base); buf[len++] = (char)(digit < 10 ? '0' + digit : (flags & FLAGS_UPPERCASE ? 'A' : 'a') + digit - 10); value /= base; } while (value && (len < PRINTF_INTEGER_BUFFER_SIZE)); } print_integer_finalization(output, putc_function, buf, len, negative, base, precision, width, flags); } #if (CONFIG_VLIBC_FLOAT || CONFIG_VLIBC_FLOAT_EX) // Stores a fixed-precision representation of a double relative // to a fixed precision (which cannot be determined by examining this structure) struct double_components { int_fast64_t integral; int_fast64_t fractional; // ... truncation of the actual fractional part of the double value, scaled // by the precision value bool is_negative; }; #define NUM_DECIMAL_DIGITS_IN_INT64_T 18 #define PRINTF_MAX_PRECOMPUTED_POWER_OF_10 NUM_DECIMAL_DIGITS_IN_INT64_T static const double powers_of_10[NUM_DECIMAL_DIGITS_IN_INT64_T] = { 1e00, 1e01, 1e02, 1e03, 1e04, 1e05, 1e06, 1e07, 1e08, 1e09, 1e10, 1e11, 1e12, 1e13, 1e14, 1e15, 1e16, 1e17 }; #define PRINTF_MAX_SUPPORTED_PRECISION NUM_DECIMAL_DIGITS_IN_INT64_T - 1 // Break up a double number - which is known to be a finite non-negative number - // into its base-10 parts: integral - before the decimal point, and fractional - after it. // Taken the precision into account, but does not change it even internally. static struct double_components get_components(double number, size_t precision) { struct double_components number_; number_.is_negative = get_sign_bit(number); double abs_number = (number_.is_negative) ? -number : number; number_.integral = (int_fast64_t)abs_number; double remainder = (abs_number - (double)number_.integral) * powers_of_10[precision]; number_.fractional = (int_fast64_t)remainder; remainder -= (double)number_.fractional; if (remainder > 0.5) { ++number_.fractional; // handle rollover, e.g. case 0.99 with precision 1 is 1.0 if ((double)number_.fractional >= powers_of_10[precision]) { number_.fractional = 0; ++number_.integral; } } else if ((remainder == 0.5) && ((number_.fractional == 0U) || (number_.fractional & 1U))) { // if halfway, round up if odd OR if last digit is 0 ++number_.fractional; } if (precision == 0U) { remainder = abs_number - (double)number_.integral; if ((!(remainder < 0.5) || (remainder > 0.5)) && (number_.integral & 1)) { // exactly 0.5 and ODD, then round up // 1.5 -> 2, but 2.5 -> 2 ++number_.integral; } } return number_; } #if CONFIG_VLIBC_FLOAT_EX struct scaling_factor { double raw_factor; bool multiply; // if true, need to multiply by raw_factor; otherwise need to divide by it }; static double apply_scaling(double num, struct scaling_factor normalization) { return normalization.multiply ? num * normalization.raw_factor : num / normalization.raw_factor; } static double unapply_scaling(double normalized, struct scaling_factor normalization) { return normalization.multiply ? normalized / normalization.raw_factor : normalized * normalization.raw_factor; } static struct scaling_factor update_normalization(struct scaling_factor sf, double extra_multiplicative_factor) { struct scaling_factor result; if (sf.multiply) { result.multiply = true; result.raw_factor = sf.raw_factor * extra_multiplicative_factor; } else { int factor_exp2 = get_exp2(get_bit_access(sf.raw_factor)); int extra_factor_exp2 = get_exp2(get_bit_access(extra_multiplicative_factor)); // Divide the larger-exponent raw raw_factor by the smaller if (PRINTF_ABS(factor_exp2) > PRINTF_ABS(extra_factor_exp2)) { result.multiply = false; result.raw_factor = sf.raw_factor / extra_multiplicative_factor; } else { result.multiply = true; result.raw_factor = extra_multiplicative_factor / sf.raw_factor; } } return result; } static struct double_components get_normalized_components(bool negative, size_t precision, double non_normalized, struct scaling_factor normalization, int floored_exp10) { struct double_components components; components.is_negative = negative; double scaled = apply_scaling(non_normalized, normalization); bool close_to_representation_extremum = ((-floored_exp10 + (int)precision) >= DBL_MAX_10_EXP - 1); if (close_to_representation_extremum) { // We can't have a normalization factor which also accounts for the precision, i.e. moves // some decimal digits into the mantissa, since it's unrepresentable, or nearly unrepresentable. // So, we'll give up early on getting extra precision... return get_components(negative ? -scaled : scaled, precision); } components.integral = (int_fast64_t)scaled; double remainder = non_normalized - unapply_scaling((double)components.integral, normalization); double prec_power_of_10 = powers_of_10[precision]; struct scaling_factor account_for_precision = update_normalization(normalization, prec_power_of_10); double scaled_remainder = apply_scaling(remainder, account_for_precision); double rounding_threshold = 0.5; components.fractional = (int_fast64_t)scaled_remainder; // when precision == 0, the assigned value should be 0 scaled_remainder -= (double)components.fractional; //when precision == 0, this will not change scaled_remainder components.fractional += (scaled_remainder >= rounding_threshold); if (scaled_remainder == rounding_threshold) { // banker's rounding: Round towards the even number (making the mean error 0) components.fractional &= ~((int_fast64_t)0x1); } // handle rollover, e.g. the case of 0.99 with precision 1 becoming (0,100), // and must then be corrected into (1, 0). // Note: for precision = 0, this will "translate" the rounding effect from // the fractional part to the integral part where it should actually be // felt (as prec_power_of_10 is 1) if ((double)components.fractional >= prec_power_of_10) { components.fractional = 0; ++components.integral; } return components; } #endif // CONFIG_VLIBC_FLOAT_EX static void print_broken_up_decimal( struct double_components number_, output_gadget_t *output, void (*putc_function)(output_gadget_t *, char), size_t precision, size_t width, printf_flags_t flags, char *buf, size_t len) { if (precision != 0U) { // do fractional part, as an unsigned number size_t count = precision; // %g/%G mandates we skip the trailing 0 digits... if ((flags & FLAGS_ADAPT_EXP) && !(flags & FLAGS_HASH) && (number_.fractional > 0)) { while (true) { int_fast64_t digit = number_.fractional % 10U; if (digit != 0) { break; } --count; number_.fractional /= 10U; } // ... and even the decimal point if there are no // non-zero fractional part digits (see below) } if (number_.fractional > 0 || !(flags & FLAGS_ADAPT_EXP) || (flags & FLAGS_HASH)) { while (len < PRINTF_DECIMAL_BUFFER_SIZE) { --count; buf[len++] = (char)('0' + number_.fractional % 10U); if (!(number_.fractional /= 10U)) { break; } } // add extra 0s while ((len < PRINTF_DECIMAL_BUFFER_SIZE) && (count > 0U)) { buf[len++] = '0'; --count; } if (len < PRINTF_DECIMAL_BUFFER_SIZE) { buf[len++] = '.'; } } } else { if ((flags & FLAGS_HASH) && (len < PRINTF_DECIMAL_BUFFER_SIZE)) { buf[len++] = '.'; } } // Write the integer part of the number (it comes after the fractional // since the character order is reversed) while (len < PRINTF_DECIMAL_BUFFER_SIZE) { buf[len++] = (char)('0' + (number_.integral % 10)); if (!(number_.integral /= 10)) { break; } } // pad leading zeros if (!(flags & FLAGS_LEFT) && (flags & FLAGS_ZEROPAD)) { if (width && (number_.is_negative || (flags & (FLAGS_PLUS | FLAGS_SPACE)))) { width--; } while ((len < width) && (len < PRINTF_DECIMAL_BUFFER_SIZE)) { buf[len++] = '0'; } } if (len < PRINTF_DECIMAL_BUFFER_SIZE) { if (number_.is_negative) { buf[len++] = '-'; } else if (flags & FLAGS_PLUS) { buf[len++] = '+'; // ignore the space if the '+' exists } else if (flags & FLAGS_SPACE) { buf[len++] = ' '; } } out_rev_(output, putc_function, buf, len, width, flags); } // internal ftoa for fixed decimal floating point static void print_decimal_number(output_gadget_t *output, void (*putc_function)(output_gadget_t *, char), double number, size_t precision, size_t width, printf_flags_t flags, char *buf, size_t len) { struct double_components value_ = get_components(number, precision); print_broken_up_decimal(value_, output, putc_function, precision, width, flags, buf, len); } #if CONFIG_VLIBC_FLOAT_EX // A floor function - but one which only works for numbers whose // floor value is representable by an int. static int bastardized_floor(double x) { if (x >= 0) { return (int)x; } int n = (int)x; return (((double)n) == x) ? n : n - 1; } // Computes the base-10 logarithm of the input number - which must be an actual // positive number (not infinity or NaN, nor a sub-normal) static double log10_of_positive(double positive_number) { // The implementation follows David Gay (https://www.ampl.com/netlib/fp/dtoa.c). // // Since log_10 ( M * 2^x ) = log_10(M) + x , we can separate the components of // our input number, and need only solve log_10(M) for M between 1 and 2 (as // the base-2 mantissa is always 1-point-something). In that limited range, a // Taylor series expansion of log10(x) should serve us well enough; and we'll // take the mid-point, 1.5, as the point of expansion. double_with_bit_access dwba = get_bit_access(positive_number); // based on the algorithm by David Gay (https://www.ampl.com/netlib/fp/dtoa.c) int exp2 = get_exp2(dwba); // drop the exponent, so dwba.F comes into the range [1,2) dwba.U = (dwba.U & (((double_uint_t)(1) << DOUBLE_STORED_MANTISSA_BITS) - 1U)) | ((double_uint_t)DOUBLE_BASE_EXPONENT << DOUBLE_STORED_MANTISSA_BITS); double z = (dwba.F - 1.5); return ( // Taylor expansion around 1.5: 0.1760912590556812420 // Expansion term 0: ln(1.5) / ln(10) + z * 0.2895296546021678851 // Expansion term 1: (M - 1.5) * 2/3 / ln(10) #if PRINTF_LOG10_TAYLOR_TERMS > 2 - z * z * 0.0965098848673892950 // Expansion term 2: (M - 1.5)^2 * 2/9 / ln(10) #if PRINTF_LOG10_TAYLOR_TERMS > 3 + z * z * z * 0.0428932821632841311 // Expansion term 2: (M - 1.5)^3 * 8/81 / ln(10) #endif #endif // exact log_2 of the exponent x, with logarithm base change + exp2 * 0.30102999566398119521 // = exp2 * log_10(2) = exp2 * ln(2)/ln(10) ); } static double pow10_of_int(int floored_exp10) { // A crude hack for avoiding undesired behavior with barely-normal or slightly-subnormal values. if (floored_exp10 == DOUBLE_MAX_SUBNORMAL_EXPONENT_OF_10) { return DOUBLE_MAX_SUBNORMAL_POWER_OF_10; } // Compute 10^(floored_exp10) but (try to) make sure that doesn't overflow double_with_bit_access dwba; int exp2 = bastardized_floor(floored_exp10 * 3.321928094887362 + 0.5); const double z = floored_exp10 * 2.302585092994046 - exp2 * 0.6931471805599453; const double z2 = z * z; dwba.U = ((double_uint_t)(exp2) + DOUBLE_BASE_EXPONENT) << DOUBLE_STORED_MANTISSA_BITS; // compute exp(z) using continued fractions, // see https://en.wikipedia.org/wiki/Exponential_function#Continued_fractions_for_ex dwba.F *= 1 + 2 * z / (2 - z + (z2 / (6 + (z2 / (10 + z2 / 14))))); return dwba.F; } static void print_exponential_number(output_gadget_t *output, void (*putc_function)(output_gadget_t *, char), double number, size_t precision, size_t width, printf_flags_t flags, char *buf, size_t len) { const bool negative = get_sign_bit(number); // This number will decrease gradually (by factors of 10) as we "extract" the exponent out of it double abs_number = negative ? -number : number; int floored_exp10; bool abs_exp10_covered_by_powers_table; struct scaling_factor normalization; // Determine the decimal exponent if (abs_number == 0.0) { // TODO: This is a special-case for 0.0 (and -0.0); but proper handling is required for denormals more generally. floored_exp10 = 0; // ... and no need to set a normalization factor or check the powers table } else { double exp10 = log10_of_positive(abs_number); floored_exp10 = bastardized_floor(exp10); double p10 = pow10_of_int(floored_exp10); // correct for rounding errors if (abs_number < p10) { floored_exp10--; p10 /= 10; } abs_exp10_covered_by_powers_table = PRINTF_ABS(floored_exp10) < PRINTF_MAX_PRECOMPUTED_POWER_OF_10; normalization.raw_factor = abs_exp10_covered_by_powers_table ? powers_of_10[PRINTF_ABS(floored_exp10)] : p10; } // We now begin accounting for the widths of the two parts of our printed field: // the decimal part after decimal exponent extraction, and the base-10 exponent part. // For both of these, the value of 0 has a special meaning, but not the same one: // a 0 exponent-part width means "don't print the exponent"; a 0 decimal-part width // means "use as many characters as necessary". bool fall_back_to_decimal_only_mode = false; if (flags & FLAGS_ADAPT_EXP) { int required_significant_digits = (precision == 0) ? 1 : (int)precision; // Should we want to fall-back to "%f" mode, and only print the decimal part? fall_back_to_decimal_only_mode = (floored_exp10 >= -4 && floored_exp10 < required_significant_digits); // Now, let's adjust the precision // This also decided how we adjust the precision value - as in "%g" mode, // "precision" is the number of _significant digits_, and this is when we "translate" // the precision value to an actual number of decimal digits. int precision_ = fall_back_to_decimal_only_mode ? (int)precision - 1 - floored_exp10 : (int)precision - 1; // the presence of the exponent ensures only one significant digit comes before the decimal point precision = (precision_ > 0 ? (unsigned)precision_ : 0U); flags |= FLAGS_PRECISION; // make sure print_broken_up_decimal respects our choice above } normalization.multiply = (floored_exp10 < 0 && abs_exp10_covered_by_powers_table); bool should_skip_normalization = (fall_back_to_decimal_only_mode || floored_exp10 == 0); struct double_components decimal_part_components = should_skip_normalization ? get_components(negative ? -abs_number : abs_number, precision) : get_normalized_components(negative, precision, abs_number, normalization, floored_exp10); // Account for roll-over, e.g. rounding from 9.99 to 100.0 - which effects // the exponent and may require additional tweaking of the parts if (fall_back_to_decimal_only_mode) { if ((flags & FLAGS_ADAPT_EXP) && floored_exp10 >= -1 && decimal_part_components.integral == powers_of_10[floored_exp10 + 1]) { floored_exp10++; // Not strictly necessary, since floored_exp10 is no longer really used precision--; // ... and it should already be the case that decimal_part_components.fractional == 0 } // TODO: What about rollover strictly within the fractional part? } else { if (decimal_part_components.integral >= 10) { floored_exp10++; decimal_part_components.integral = 1; decimal_part_components.fractional = 0; } } // the floored_exp10 format is "E%+03d" and largest possible floored_exp10 value for a 64-bit double // is "307" (for 2^1023), so we set aside 4-5 characters overall size_t exp10_part_width = fall_back_to_decimal_only_mode ? 0U : (PRINTF_ABS(floored_exp10) < 100) ? 4U : 5U; size_t decimal_part_width = ((flags & FLAGS_LEFT) && exp10_part_width) ? // We're padding on the right, so the width constraint is the exponent part's // problem, not the decimal part's, so we'll use as many characters as we need: 0U : // We're padding on the left; so the width constraint is the decimal part's // problem. Well, can both the decimal part and the exponent part fit within our overall width? ((width > exp10_part_width) ? // Yes, so we limit our decimal part's width. // (Note this is trivially valid even if we've fallen back to "%f" mode) width - exp10_part_width : // No; we just give up on any restriction on the decimal part and use as many // characters as we need 0U); const size_t printed_exponential_start_pos = output->pos; print_broken_up_decimal(decimal_part_components, output, putc_function, precision, decimal_part_width, flags, buf, len); if (!fall_back_to_decimal_only_mode) { putc_function(output, (flags & FLAGS_UPPERCASE) ? 'E' : 'e'); print_integer(output, putc_function, ABS_FOR_PRINTING(floored_exp10), floored_exp10 < 0, 10, 0, exp10_part_width - 1, FLAGS_ZEROPAD | FLAGS_PLUS); if (flags & FLAGS_LEFT) { // We need to right-pad with spaces to meet the width requirement while (output->pos - printed_exponential_start_pos < width) { putc_function(output, ' '); } } } } #endif // CONFIG_VLIBC_FLOAT_EX static void print_floating_point(output_gadget_t *output, void (*putc_function)(output_gadget_t *, char), double value, size_t precision, size_t width, printf_flags_t flags, bool prefer_exponential) { char buf[PRINTF_DECIMAL_BUFFER_SIZE]; size_t len = 0U; // test for special values if (value != value) { out_rev_(output, putc_function, "nan", 3, width, flags); return; } if (value < -DBL_MAX) { out_rev_(output, putc_function, "fni-", 4, width, flags); return; } if (value > DBL_MAX) { out_rev_(output, putc_function, (flags & FLAGS_PLUS) ? "fni+" : "fni", (flags & FLAGS_PLUS) ? 4U : 3U, width, flags); return; } if (!prefer_exponential && ((value > PRINTF_FLOAT_NOTATION_THRESHOLD) || (value < -PRINTF_FLOAT_NOTATION_THRESHOLD))) { // The required behavior of standard printf is to print _every_ integral-part digit -- which could mean // printing hundreds of characters, overflowing any fixed internal buffer and necessitating a more complicated // implementation. #if CONFIG_VLIBC_FLOAT_EX print_exponential_number(output, putc_function, value, precision, width, flags, buf, len); #endif return; } // set default precision, if not set explicitly if (!(flags & FLAGS_PRECISION)) { precision = VLIBC_DEFAULT_FLOAT_PRECISION; } // limit precision so that our integer holding the fractional part does not overflow while ((len < PRINTF_DECIMAL_BUFFER_SIZE) && (precision > PRINTF_MAX_SUPPORTED_PRECISION)) { buf[len++] = '0'; // This respects the precision in terms of result length only precision--; } #if CONFIG_VLIBC_FLOAT_EX if (prefer_exponential) print_exponential_number(output, putc_function, value, precision, width, flags, buf, len); else #endif print_decimal_number(output, putc_function, value, precision, width, flags, buf, len); } #endif // (CONFIG_VLIBC_FLOAT || CONFIG_VLIBC_FLOAT_EX) // Advances the format pointer past the flags, and returns the parsed flags // due to the characters passed static printf_flags_t parse_flags(const char **format) { printf_flags_t flags = 0U; do { switch (**format) { case '0': flags |= FLAGS_ZEROPAD; (*format)++; break; case '-': flags |= FLAGS_LEFT; (*format)++; break; case '+': flags |= FLAGS_PLUS; (*format)++; break; case ' ': flags |= FLAGS_SPACE; (*format)++; break; case '#': flags |= FLAGS_HASH; (*format)++; break; default: return flags; } } while (true); } // internal vsnprintf - used for implementing _all library functions // Note: We don't like the C standard's parameter names, so using more informative parameter names // here instead. static int _vsnprintf(output_gadget_t *output, void (*putc_function)(output_gadget_t *, char), const char *format, va_list args) { // Note: The library only calls _vsnprintf() with output->pos being 0. However, it is // possible to call this function with a non-zero pos value for some "remedial printing". while (*format) { // format specifier? %[flags][width][.precision][length] if (*format != '%') { putc_function(output, *format); format++; continue; } else { format++; } printf_flags_t flags = parse_flags(&format); // evaluate width field size_t width = 0U; if (is_digit_(*format)) { width = (size_t)atou_(&format); } else if (*format == '*') { const int w = va_arg(args, int); if (w < 0) { flags |= FLAGS_LEFT; // reverse padding width = (size_t)-w; } else { width = (size_t)w; } format++; } // evaluate precision field size_t precision = 0U; if (*format == '.') { flags |= FLAGS_PRECISION; format++; if (is_digit_(*format)) { precision = (size_t)atou_(&format); } else if (*format == '*') { const int precision_ = va_arg(args, int); precision = precision_ > 0 ? (size_t)precision_ : 0U; format++; } } // evaluate length field switch (*format) { case 'l': flags |= FLAGS_LONG; format++; if (*format == 'l') { flags |= FLAGS_LONG_LONG; format++; } break; case 'h': flags |= FLAGS_SHORT; format++; if (*format == 'h') { flags |= FLAGS_CHAR; format++; } break; case 't': flags |= (sizeof(ptrdiff_t) == sizeof(long) ? FLAGS_LONG : FLAGS_LONG_LONG); format++; break; case 'j': flags |= (sizeof(intmax_t) == sizeof(long) ? FLAGS_LONG : FLAGS_LONG_LONG); format++; break; case 'z': flags |= (sizeof(size_t) == sizeof(long) ? FLAGS_LONG : FLAGS_LONG_LONG); format++; break; default: break; } // evaluate specifier switch (*format) { case 'd': case 'i': case 'u': case 'x': case 'X': case 'o': case 'b': { if (*format == 'd' || *format == 'i') { flags |= FLAGS_SIGNED; } numeric_base_t base; if (*format == 'x' || *format == 'X') { base = BASE_HEX; } else if (*format == 'o') { base = BASE_OCTAL; } else if (*format == 'b') { base = BASE_BINARY; } else { base = BASE_DECIMAL; flags &= ~FLAGS_HASH; // decimal integers have no alternative presentation } if (*format == 'X') { flags |= FLAGS_UPPERCASE; } format++; // ignore '0' flag when precision is given if (flags & FLAGS_PRECISION) { flags &= ~FLAGS_ZEROPAD; } if (flags & FLAGS_SIGNED) { // A signed specifier: d, i or possibly I + bit size if enabled if (flags & FLAGS_LONG_LONG) { #if CONFIG_VLIBC_LONG_LONG const long long value = va_arg(args, long long); print_integer(output, putc_function, ABS_FOR_PRINTING(value), value < 0, base, precision, width, flags); #endif } else if (flags & FLAGS_LONG) { const long value = va_arg(args, long); print_integer(output, putc_function, ABS_FOR_PRINTING(value), value < 0, base, precision, width, flags); } else { // We never try to interpret the argument as something potentially-smaller than int, // due to integer promotion rules: Even if the user passed a short int, short unsigned // etc. - these will come in after promotion, as int's (or unsigned for the case of // short unsigned when it has the same size as int) const int value = (flags & FLAGS_CHAR) ? (signed char)va_arg(args, int) : (flags & FLAGS_SHORT) ? (short int)va_arg(args, int) : va_arg(args, int); print_integer(output, putc_function, ABS_FOR_PRINTING(value), value < 0, base, precision, width, flags); } } else { // An unsigned specifier: u, x, X, o, b flags &= ~(FLAGS_PLUS | FLAGS_SPACE); if (flags & FLAGS_LONG_LONG) { #if CONFIG_VLIBC_LONG_LONG print_integer(output, putc_function, (printf_unsigned_value_t)va_arg(args, unsigned long long), false, base, precision, width, flags); #endif } else if (flags & FLAGS_LONG) { print_integer(output, putc_function, (printf_unsigned_value_t)va_arg(args, unsigned long), false, base, precision, width, flags); } else { const unsigned int value = (flags & FLAGS_CHAR) ? (unsigned char)va_arg(args, unsigned int) : (flags & FLAGS_SHORT) ? (unsigned short int)va_arg(args, unsigned int) : va_arg(args, unsigned int); print_integer(output, putc_function, (printf_unsigned_value_t)value, false, base, precision, width, flags); } } break; } #if CONFIG_VLIBC_FLOAT case 'f': case 'F': if (*format == 'F') flags |= FLAGS_UPPERCASE; print_floating_point(output, putc_function, va_arg(args, double), precision, width, flags, PRINTF_PREFER_DECIMAL); format++; break; #endif #if CONFIG_VLIBC_FLOAT_EX case 'e': case 'E': case 'g': case 'G': if ((*format == 'g') || (*format == 'G')) flags |= FLAGS_ADAPT_EXP; if ((*format == 'E') || (*format == 'G')) flags |= FLAGS_UPPERCASE; print_floating_point(output, putc_function, va_arg(args, double), precision, width, flags, PRINTF_PREFER_EXPONENTIAL); format++; break; #endif case 'c': { size_t l = 1U; // pre padding if (!(flags & FLAGS_LEFT)) { while (l++ < width) { putc_function(output, ' '); } } // char output putc_function(output, (char)va_arg(args, int)); // post padding if (flags & FLAGS_LEFT) { while (l++ < width) { putc_function(output, ' '); } } format++; break; } case 's': { const char *p = va_arg(args, char *); if (p == NULL) { out_rev_(output, putc_function, ")llun(", 6, width, flags); } else { size_t l = strnlen_s_(p, precision ? precision : PRINTF_MAX_POSSIBLE_BUFFER_SIZE); // pre padding if (flags & FLAGS_PRECISION) { l = (l < precision ? l : precision); } if (!(flags & FLAGS_LEFT)) { while (l++ < width) { putc_function(output, ' '); } } // string output while ((*p != 0) && (!(flags & FLAGS_PRECISION) || precision)) { putc_function(output, *(p++)); --precision; } // post padding if (flags & FLAGS_LEFT) { while (l++ < width) { putc_function(output, ' '); } } } format++; break; } case 'p': { width = sizeof(void *) * 2U + 2; // 2 hex chars per byte + the "0x" prefix flags |= FLAGS_ZEROPAD | FLAGS_POINTER; uintptr_t value = (uintptr_t)va_arg(args, void *); (value == (uintptr_t)NULL) ? out_rev_(output, putc_function, ")lin(", 5, width, flags) : print_integer(output, putc_function, (printf_unsigned_value_t)value, false, BASE_HEX, precision, width, flags); format++; break; } case '%': putc_function(output, '%'); format++; break; // Many people prefer to disable support for %n, as it lets the caller // engineer a write to an arbitrary location, of a value the caller // effectively controls - which could be a security concern in some cases. #if CONFIG_VLIBC_WRITEBACK case 'n': { if (flags & FLAGS_CHAR) *(va_arg(args, char *)) = (char)output->pos; else if (flags & FLAGS_SHORT) *(va_arg(args, short *)) = (short)output->pos; else if (flags & FLAGS_LONG) *(va_arg(args, long *)) = (long)output->pos; #if CONFIG_VLIBC_LONG_LONG else if (flags & FLAGS_LONG_LONG) *(va_arg(args, long long *)) = (long long int)output->pos; #endif // CONFIG_VLIBC_LONG_LONG else *(va_arg(args, int *)) = (int)output->pos; format++; break; } #endif // CONFIG_VLIBC_WRITEBACK default: putc_function(output, *format); format++; break; } } // termination append \0 if ((output->stream == NULL) && (output->buffer != NULL) && (output->max > 0)) { size_t null_char_pos = output->pos < output->max ? output->pos : output->max - 1; output->buffer[null_char_pos] = '\0'; } // return written chars without terminating \0 return (int)output->pos; } /** @addtogroup api ********************************************************** * @{ */ /** * @brief * @param stream * @param format * @param arg * @return int */ // int vfprintf(FILE *__restrict, const char *__restrict, __VALIST) __attribute__((alias("vlibc_vfprintf"))); int vlibc_vfprintf(VLIBC_FILE *stream, const char *format, va_list arg) { CHECK_FILE(stream, EOF); CHECK_FILE(format, EOF); output_gadget_t gadget; gadget.stream = stream; gadget.buffer = NULL; gadget.pos = 0; gadget.max = PRINTF_MAX_POSSIBLE_BUFFER_SIZE; IF_IO_DEV(stream) { switch (stream->io->vbuf) { case _IOFBF: if (stream->io->wp == stream->io->ed) { if (__vlibc_io_mem2dev(stream->io, stream->io->bg, stream->io->ed - stream->io->bg) == 0) { errno = EINVAL; } stream->io->wp = stream->io->bg; } return _vsnprintf(&gadget, putc_via_iodev_fbf, format, arg); case _IOLBF: if (stream->io->wp == stream->io->ed) { if (__vlibc_io_mem2dev(stream->io, stream->io->bg, stream->io->ed - stream->io->bg) == 0) { errno = EINVAL; } stream->io->wp = stream->io->bg; } return _vsnprintf(&gadget, putc_via_iodev_lbf, format, arg); case _IONBF: return _vsnprintf(&gadget, putc_via_iodev_nbf, format, arg); default: errno = EINVAL; return EOF; } } else IF_FILE(stream) { #ifdef CONFIG_VLIBC_FATFS char buffer[VLIBC_FBUFSIZ]; int ret; FRESULT fresult; size_t bytes; gadget.buffer = buffer; gadget.max = 0; ret = _vsnprintf(&gadget, putc_via_file, format, arg); fresult = f_write(stream->file, buffer, gadget.max, &bytes); if (fresult != FR_OK) { if (fresult <= FR_INVALID_PARAMETER) { errno = FRESULT_to_errno[fresult]; } } return ret; #else return EOF; #endif } else { errno = EINVAL; return EOF; } } /** * @brief * @param format * @param arg * @return int */ // int vprintf(const char *, __VALIST) __attribute__((alias("vlibc_vprintf"))); int vlibc_vprintf(const char *format, va_list arg) { return vlibc_vfprintf(vlibc_stdout, format, arg); } /** * @brief * @param str * @param size * @param format * @param arg * @return int */ int vsnprintf(char *__restrict, size_t, const char *__restrict, __VALIST) __attribute__((alias("vlibc_vsnprintf"))); int vlibc_vsnprintf(char *str, size_t size, const char *format, va_list arg) { CHECK_FILE(str, EOF); CHECK_FILE(format, EOF); output_gadget_t gadget; gadget.stream = NULL; gadget.buffer = str; gadget.pos = 0; gadget.max = size; return _vsnprintf(&gadget, putc_via_buffer, format, arg); } /** * @brief * @param str * @param format * @param arg * @return int */ // int vsprintf(char *__restrict, const char *__restrict, __VALIST) __attribute__((alias("vlibc_vsprintf"))); int vlibc_vsprintf(char *str, const char *format, va_list arg) { return vlibc_vsnprintf(str, PRINTF_MAX_POSSIBLE_BUFFER_SIZE, format, arg); } /** * @brief * @param stream * @param format * @param ... * @return int */ // int fprintf(FILE *__restrict, const char *__restrict, ...) __attribute__((alias("vlibc_fprintf"))); int vlibc_fprintf(VLIBC_FILE *stream, const char *format, ...) { va_list args; va_start(args, format); const int ret = vlibc_vfprintf(stream, format, args); va_end(args); return ret; } /** * @brief * @param format * @param ... * @return int */ int printf(const char *__restrict, ...) __attribute__((alias("vlibc_printf"))); int vlibc_printf(const char *format, ...) { va_list args; va_start(args, format); const int ret = vlibc_vprintf(format, args); va_end(args); return ret; } /** * @brief * @param str * @param format * @param ... * @return int */ // int sprintf(char *__restrict, const char *__restrict, ...) __attribute__((alias("vlibc_sprintf"))); int vlibc_sprintf(char *str, const char *format, ...) { va_list args; va_start(args, format); const int ret = vlibc_vsprintf(str, format, args); va_end(args); return ret; } /** * @brief * @param str * @param size * @param format * @param ... * @return int */ // int snprintf(char *__restrict, size_t, const char *__restrict, ...) __attribute__((alias("vlibc_snprintf"))); int vlibc_snprintf(char *str, size_t size, const char *format, ...) { va_list args; va_start(args, format); const int ret = vlibc_vsnprintf(str, size, format, args); va_end(args); return ret; } /** * @} */