/*
* Copyright (c) 2021, Meco Jianting Man <jiantingman@foxmail.com>
*
* SPDX-License-Identifier: Apache-2.0
*
* Change Logs:
* Date Author Notes
* 2021-11-27 Meco Man porting for rt_vsnprintf as the fully functional version
*//**
* @author (c) Eyal Rozenberg <eyalroz1@gmx.com>
* 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 <m.jasperse@gmail.com>.
*
* @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<stdio.h>#include<stdint.h>#include<limits.h>#include<stdbool.h>#include<rtconfig.h>#include<rtdef.h>//#ifndef RT_VER_NUM /* Doesn't use menuconfig */// 'ntoa' conversion buffer size, this must be big enough to hold one converted// numeric number including padded zeros (dynamically created on stack)#ifndefPKG_VSNPRINTF_INTEGER_BUFFER_SIZE#definePKG_VSNPRINTF_INTEGER_BUFFER_SIZE32#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.#ifndefPKG_VSNPRINTF_DECIMAL_BUFFER_SIZE#definePKG_VSNPRINTF_DECIMAL_BUFFER_SIZE32#endif// Support for the decimal notation floating point conversion specifiers (%f, %F)#ifndefPKG_VSNPRINTF_SUPPORT_DECIMAL_SPECIFIERS#definePKG_VSNPRINTF_SUPPORT_DECIMAL_SPECIFIERS#endif// Support for the exponential notation floating point conversion specifiers (%e, %g, %E, %G)#ifndefPKG_VSNPRINTF_SUPPORT_EXPONENTIAL_SPECIFIERS#definePKG_VSNPRINTF_SUPPORT_EXPONENTIAL_SPECIFIERS#endif// Support for the length write-back specifier (%n)#ifndefPKG_VSNPRINTF_SUPPORT_WRITEBACK_SPECIFIER#definePKG_VSNPRINTF_SUPPORT_WRITEBACK_SPECIFIER#endif// Default precision for the floating point conversion specifiers (the C standard sets this at 6)#ifndefPKG_VSNPRINTF_DEFAULT_FLOAT_PRECISION#definePKG_VSNPRINTF_DEFAULT_FLOAT_PRECISION6#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.#ifndefPKG_VSNPRINTF_MAX_INTEGRAL_DIGITS_FOR_DECIMAL#definePKG_VSNPRINTF_MAX_INTEGRAL_DIGITS_FOR_DECIMAL9#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.#ifndefPKG_VSNPRINTF_SUPPORT_LONG_LONG#definePKG_VSNPRINTF_SUPPORT_LONG_LONG#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).#ifndefPKG_VSNPRINTF_LOG10_TAYLOR_TERMS#definePKG_VSNPRINTF_LOG10_TAYLOR_TERMS4#endif// Be extra-safe, and don't assume format specifiers are completed correctly// before the format string end.#ifndefPKG_VSNPRINTF_CHECK_FOR_NUL_IN_FORMAT_SPECIFIER#definePKG_VSNPRINTF_CHECK_FOR_NUL_IN_FORMAT_SPECIFIER#endif//#endif /* RT_VER_NUM */#ifPKG_VSNPRINTF_LOG10_TAYLOR_TERMS <=1#error"At least one non-constant Taylor expansion is necessary for the log10() calculation"#endif///#definePRINTF_PREFER_DECIMALfalse#definePRINTF_PREFER_EXPONENTIALtrue// The following will convert the number-of-digits into an exponential-notation literal#definePRINTF_CONCATENATE(s1, s2) s1##s2#definePRINTF_EXPAND_THEN_CONCATENATE(s1, s2)PRINTF_CONCATENATE(s1, s2)#definePRINTF_FLOAT_NOTATION_THRESHOLDPRINTF_EXPAND_THEN_CONCATENATE(1e,PKG_VSNPRINTF_MAX_INTEGRAL_DIGITS_FOR_DECIMAL)// internal flag definitions#defineFLAGS_ZEROPAD(1U<<0U)#defineFLAGS_LEFT(1U<<1U)#defineFLAGS_PLUS(1U<<2U)#defineFLAGS_SPACE(1U<<3U)#defineFLAGS_HASH(1U<<4U)#defineFLAGS_UPPERCASE(1U<<5U)#defineFLAGS_CHAR(1U<<6U)#defineFLAGS_SHORT(1U<<7U)#defineFLAGS_INT(1U<<8U)// Only used with PKG_VSNPRINTF_SUPPORT_MSVC_STYLE_INTEGER_SPECIFIERS#defineFLAGS_LONG(1U<<9U)#defineFLAGS_LONG_LONG(1U<<10U)#defineFLAGS_PRECISION(1U<<11U)#defineFLAGS_ADAPT_EXP(1U<<12U)#defineFLAGS_POINTER(1U<<13U)// Note: Similar, but not identical, effect as FLAGS_HASH#defineFLAGS_SIGNED(1U<<14U)// Only used with PKG_VSNPRINTF_SUPPORT_MSVC_STYLE_INTEGER_SPECIFIERS#ifdefPKG_VSNPRINTF_SUPPORT_MSVC_STYLE_INTEGER_SPECIFIERS#defineFLAGS_INT8FLAGS_CHAR#if(SHRT_MAX ==32767LL)#defineFLAGS_INT16FLAGS_SHORT#elif(INT_MAX ==32767LL)#defineFLAGS_INT16FLAGS_INT#elif(LONG_MAX ==32767LL)#defineFLAGS_INT16FLAGS_LONG#elif(LLONG_MAX ==32767LL)#defineFLAGS_INT16FLAGS_LONG_LONG#else#error"No basic integer type has a size of 16 bits exactly"#endif#if(SHRT_MAX ==2147483647LL)#defineFLAGS_INT32FLAGS_SHORT#elif(INT_MAX ==2147483647LL)#defineFLAGS_INT32FLAGS_INT#elif(LONG_MAX ==2147483647LL)#defineFLAGS_INT32FLAGS_LONG#elif(LLONG_MAX ==2147483647LL)#defineFLAGS_INT32FLAGS_LONG_LONG#else#error"No basic integer type has a size of 32 bits exactly"#endif#if(SHRT_MAX ==9223372036854775807LL)#defineFLAGS_INT64FLAGS_SHORT#elif(INT_MAX ==9223372036854775807LL)#defineFLAGS_INT64FLAGS_INT#elif(LONG_MAX ==9223372036854775807LL)#defineFLAGS_INT64FLAGS_LONG#elif(LLONG_MAX ==9223372036854775807LL)#defineFLAGS_INT64FLAGS_LONG_LONG#else#error"No basic integer type has a size of 64 bits exactly"#endif#endif// PKG_VSNPRINTF_SUPPORT_MSVC_STYLE_INTEGER_SPECIFIERStypedefunsignedintprintf_flags_t;#defineBASE_BINARY2#defineBASE_OCTAL8#defineBASE_DECIMAL10#defineBASE_HEX16typedefuint8_tnumeric_base_t;#ifdefPKG_VSNPRINTF_SUPPORT_LONG_LONGtypedefunsignedlonglongprintf_unsigned_value_t;typedeflonglongprintf_signed_value_t;#elsetypedefunsignedlongprintf_unsigned_value_t;typedeflongprintf_signed_value_t;#endif// The printf()-family functions return an `int`; it is therefore// unnecessary/inappropriate to use size_t - often larger than int// in practice - for non-negative related values, such as widths,// precisions, offsets into buffers used for printing and the sizes// of these buffers. instead, we use:typedefunsignedintprintf_size_t;#definePRINTF_MAX_POSSIBLE_BUFFER_SIZEINT_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'.#ifdefined(PKG_VSNPRINTF_SUPPORT_DECIMAL_SPECIFIERS)||defined(PKG_VSNPRINTF_SUPPORT_EXPONENTIAL_SPECIFIERS)#include<float.h>#ifFLT_RADIX !=2#error"Non-binary-radix floating-point types are unsupported."#endif#ifDBL_MANT_DIG ==24#defineDOUBLE_SIZE_IN_BITS32typedefuint32_tdouble_uint_t;#defineDOUBLE_EXPONENT_MASK0xFFU#defineDOUBLE_BASE_EXPONENT127#defineDOUBLE_MAX_SUBNORMAL_EXPONENT_OF_10-38#defineDOUBLE_MAX_SUBNORMAL_POWER_OF_101e-38#elifDBL_MANT_DIG ==53#defineDOUBLE_SIZE_IN_BITS64typedefuint64_tdouble_uint_t;#defineDOUBLE_EXPONENT_MASK0x7FFU#defineDOUBLE_BASE_EXPONENT1023#defineDOUBLE_MAX_SUBNORMAL_EXPONENT_OF_10-308#defineDOUBLE_MAX_SUBNORMAL_POWER_OF_101e-308#else#error"Unsupported double type configuration"#endif#defineDOUBLE_STORED_MANTISSA_BITS(DBL_MANT_DIG -1)typedefunion{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 literalsstaticinline double_with_bit_access get_bit_access(double x){
double_with_bit_access dwba;
dwba.F = x;return dwba;}staticinlineintget_sign_bit(double x){// The sign is stored in the highest bitreturn(int)(get_bit_access(x).U >>(DOUBLE_SIZE_IN_BITS -1));}staticinlineintget_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;}#definePRINTF_ABS(_x)((_x)>0?(_x):-(_x))#endif// (PKG_VSNPRINTF_SUPPORT_DECIMAL_SPECIFIERS || PKG_VSNPRINTF_SUPPORT_EXPONENTIAL_SPECIFIERS)// 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#defineABS_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_chars is 0// 2. buffer is non-null// 3. function is non-null//// ... otherwise bad things will happen.typedefstruct{void(*function)(char c,void* extra_arg);void* extra_function_arg;char* buffer;printf_size_t pos;printf_size_t max_chars;}output_gadget_t;// Note: This function currently assumes it is not passed a '\0' c,// or alternatively, that '\0' can be passed to the function in the output// gadget. The former assumption holds within the printf library. It also// assumes that the output gadget has been properly initialized.staticinlinevoidputchar_via_gadget(output_gadget_t* gadget,char c){printf_size_t write_pos = gadget->pos++;// We're _always_ increasing pos, so as to count how may characters// _would_ have been written if not for the max_chars limitationif(write_pos >= gadget->max_chars){return;}if(gadget->function !=NULL){// No check for c == '\0' .
gadget->function(c, gadget->extra_function_arg);}else{// it must be the case that gadget->buffer != NULL , due to the constraint// on output_gadget_t ; and note we're relying on write_pos being non-negative.
gadget->buffer[write_pos]= c;}}// Possibly-write the string-terminating '\0' characterstaticinlinevoidappend_termination_with_gadget(output_gadget_t* gadget){if(gadget->function !=NULL|| gadget->max_chars ==0){return;}if(gadget->buffer ==NULL){return;}printf_size_t null_char_pos = gadget->pos < gadget->max_chars ? gadget->pos : gadget->max_chars -1;
gadget->buffer[null_char_pos]='\0';}staticinlineoutput_gadget_tdiscarding_gadget(void){output_gadget_t gadget;
gadget.function =NULL;
gadget.extra_function_arg =NULL;
gadget.buffer =NULL;
gadget.pos =0;
gadget.max_chars =0;return gadget;}staticinlineoutput_gadget_tbuffer_gadget(char* buffer,size_t buffer_size){printf_size_t usable_buffer_size =(buffer_size > PRINTF_MAX_POSSIBLE_BUFFER_SIZE)?
PRINTF_MAX_POSSIBLE_BUFFER_SIZE :(printf_size_t) buffer_size;output_gadget_t result =discarding_gadget();if(buffer !=NULL){
result.buffer = buffer;
result.max_chars = usable_buffer_size;}return result;}// 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 printf_size_t// variables - hence the signature.staticinlineprintf_size_tstrnlen_s_(constchar* str,printf_size_t maxsize){constchar* s;for(s = str;*s && maxsize--;++s);return(printf_size_t)(s - str);}// internal test if char is a digit (0-9)// @return true if char is a digitstaticinline bool is_digit_(char ch){return(ch >='0')&&(ch <='9');}// internal ASCII string to printf_size_t conversionstaticprintf_size_tatou_(constchar** str){printf_size_t i =0U;while(is_digit_(**str)){
i = i *10U+(printf_size_t)(*((*str)++)-'0');}return i;}// output the specified string in reverse, taking care of any zero-paddingstaticvoidout_rev_(output_gadget_t* output,constchar* buf,printf_size_t len,printf_size_t width,printf_flags_t flags){constprintf_size_t start_pos = output->pos;// pad spaces up to given widthif(!(flags & FLAGS_LEFT)&&!(flags & FLAGS_ZEROPAD)){for(printf_size_t i = len; i < width; i++){putchar_via_gadget(output,' ');}}// reverse stringwhile(len){putchar_via_gadget(output, buf[--len]);}// append pad spaces up to given widthif(flags & FLAGS_LEFT){while(output->pos - start_pos < width){putchar_via_gadget(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)staticvoidprint_integer_finalization(output_gadget_t* output,char* buf,printf_size_t len, bool negative,numeric_base_t base,printf_size_t precision,printf_size_t width,printf_flags_t flags){printf_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 < PKG_VSNPRINTF_INTEGER_BUFFER_SIZE)){
buf[len++]='0';}}while((len < precision)&&(len < PKG_VSNPRINTF_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 hashif(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 prefixif(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 < PKG_VSNPRINTF_INTEGER_BUFFER_SIZE)){
buf[len++]='x';}elseif((base == BASE_HEX)&&(flags & FLAGS_UPPERCASE)&&(len < PKG_VSNPRINTF_INTEGER_BUFFER_SIZE)){
buf[len++]='X';}elseif((base == BASE_BINARY)&&(len < PKG_VSNPRINTF_INTEGER_BUFFER_SIZE)){
buf[len++]='b';}if(len < PKG_VSNPRINTF_INTEGER_BUFFER_SIZE){
buf[len++]='0';}}if(len < PKG_VSNPRINTF_INTEGER_BUFFER_SIZE){if(negative){
buf[len++]='-';}elseif(flags & FLAGS_PLUS){
buf[len++]='+';// ignore the space if the '+' exists}elseif(flags & FLAGS_SPACE){
buf[len++]=' ';}}out_rev_(output, buf, len, width, flags);}// An internal itoa-like functionstaticvoidprint_integer(output_gadget_t* output,printf_unsigned_value_t value, bool negative,numeric_base_t base,printf_size_t precision,printf_size_t width,printf_flags_t flags){char buf[PKG_VSNPRINTF_INTEGER_BUFFER_SIZE];printf_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.}elseif(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{constchar digit =(char)(value % base);
buf[len++]=(char)(digit <10?'0'+ digit :(flags & FLAGS_UPPERCASE ?'A':'a')+ digit -10);
value /= base;}while(value &&(len < PKG_VSNPRINTF_INTEGER_BUFFER_SIZE));}print_integer_finalization(output, buf, len, negative, base, precision, width, flags);}#ifdefined(PKG_VSNPRINTF_SUPPORT_DECIMAL_SPECIFIERS)||defined(PKG_VSNPRINTF_SUPPORT_EXPONENTIAL_SPECIFIERS)// Stores a fixed-precision representation of a double relative// to a fixed precision (which cannot be determined by examining this structure)structdouble_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;};#defineNUM_DECIMAL_DIGITS_IN_INT64_T18#definePRINTF_MAX_PRECOMPUTED_POWER_OF_10NUM_DECIMAL_DIGITS_IN_INT64_Tstaticconstdouble 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};#definePRINTF_MAX_SUPPORTED_PRECISIONNUM_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.staticstructdouble_componentsget_components(double number,printf_size_t precision){structdouble_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 1.0if((double) number_.fractional >= powers_of_10[precision]){
number_.fractional =0;++number_.integral;}}elseif((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_;}#ifdefPKG_VSNPRINTF_SUPPORT_EXPONENTIAL_SPECIFIERSstructscaling_factor{double raw_factor;
bool multiply;// if true, need to multiply by raw_factor; otherwise need to divide by it};staticdoubleapply_scaling(double num,structscaling_factor normalization){return normalization.multiply ? num * normalization.raw_factor : num / normalization.raw_factor;}staticdoubleunapply_scaling(double normalized,structscaling_factor normalization){#ifdef__GNUC__// accounting for a static analysis bug in GCC 6.x and earlier#pragmaGCC diagnostic push#pragmaGCC diagnostic ignored "-Wmaybe-uninitialized"#endifreturn normalization.multiply ? normalized / normalization.raw_factor : normalized * normalization.raw_factor;#ifdef__GNUC__#pragmaGCC diagnostic pop#endif}staticstructscaling_factorupdate_normalization(structscaling_factor sf,double extra_multiplicative_factor){structscaling_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 smallerif(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;}staticstructdouble_componentsget_normalized_components(bool negative,printf_size_t precision,double non_normalized,structscaling_factor normalization,int floored_exp10){structdouble_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...returnget_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];structscaling_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// PKG_VSNPRINTF_SUPPORT_EXPONENTIAL_SPECIFIERSstaticvoidprint_broken_up_decimal(structdouble_components number_,output_gadget_t* output,printf_size_t precision,printf_size_t width,printf_flags_t flags,char*buf,printf_size_t len){if(precision !=0U){// do fractional part, as an unsigned numberprintf_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 < PKG_VSNPRINTF_DECIMAL_BUFFER_SIZE){--count;
buf[len++]=(char)('0'+ number_.fractional %10U);if(!(number_.fractional /=10U)){break;}}// add extra 0swhile((len < PKG_VSNPRINTF_DECIMAL_BUFFER_SIZE)&&(count >0U)){
buf[len++]='0';--count;}if(len < PKG_VSNPRINTF_DECIMAL_BUFFER_SIZE){
buf[len++]='.';}}}else{if((flags & FLAGS_HASH)&&(len < PKG_VSNPRINTF_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 < PKG_VSNPRINTF_DECIMAL_BUFFER_SIZE){
buf[len++]=(char)('0'+(number_.integral %10));if(!(number_.integral /=10)){break;}}// pad leading zerosif(!(flags & FLAGS_LEFT)&&(flags & FLAGS_ZEROPAD)){if(width &&(number_.is_negative ||(flags &(FLAGS_PLUS | FLAGS_SPACE)))){
width--;}while((len < width)&&(len < PKG_VSNPRINTF_DECIMAL_BUFFER_SIZE)){
buf[len++]='0';}}if(len < PKG_VSNPRINTF_DECIMAL_BUFFER_SIZE){if(number_.is_negative){
buf[len++]='-';}elseif(flags & FLAGS_PLUS){
buf[len++]='+';// ignore the space if the '+' exists}elseif(flags & FLAGS_SPACE){
buf[len++]=' ';}}out_rev_(output, buf, len, width, flags);}// internal ftoa for fixed decimal floating pointstaticvoidprint_decimal_number(output_gadget_t* output,double number,printf_size_t precision,printf_size_t width,printf_flags_t flags,char* buf,printf_size_t len){structdouble_components value_ =get_components(number, precision);print_broken_up_decimal(value_, output, precision, width, flags, buf, len);}#ifdefPKG_VSNPRINTF_SUPPORT_EXPONENTIAL_SPECIFIERS// A floor function - but one which only works for numbers whose// floor value is representable by an int.staticintbastardized_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)staticdoublelog10_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)#ifPKG_VSNPRINTF_LOG10_TAYLOR_TERMS >2- z*z *0.0965098848673892950// Expansion term 2: (M - 1.5)^2 * 2/9 / ln(10)#ifPKG_VSNPRINTF_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));}staticdoublepow10_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);constdouble z = floored_exp10 *2.302585092994046- exp2 *0.6931471805599453;constdouble 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;}staticvoidprint_exponential_number(output_gadget_t* output,double number,printf_size_t precision,printf_size_t width,printf_flags_t flags,char* buf,printf_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 itdouble abs_number = negative ?-number : number;int floored_exp10;
bool abs_exp10_covered_by_powers_table;structscaling_factor normalization;// Determine the decimal exponentif(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 errorsif(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);structdouble_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 partsif(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 overallprintf_size_t exp10_part_width = fall_back_to_decimal_only_mode ?0U:(PRINTF_ABS(floored_exp10)<100)?4U:5U;printf_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 need0U);constprintf_size_t printed_exponential_start_pos = output->pos;print_broken_up_decimal(decimal_part_components, output, precision, decimal_part_width, flags, buf, len);if(! fall_back_to_decimal_only_mode){putchar_via_gadget(output,(flags & FLAGS_UPPERCASE)?'E':'e');print_integer(output,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 requirementwhile(output->pos - printed_exponential_start_pos < width){putchar_via_gadget(output,' ');}}}}#endif// PKG_VSNPRINTF_SUPPORT_EXPONENTIAL_SPECIFIERSstaticvoidprint_floating_point(output_gadget_t* output,double value,printf_size_t precision,printf_size_t width,printf_flags_t flags, bool prefer_exponential){char buf[PKG_VSNPRINTF_DECIMAL_BUFFER_SIZE];printf_size_t len =0U;// test for special valuesif(value != value){out_rev_(output,"nan",3, width, flags);return;}if(value <-DBL_MAX){out_rev_(output,"fni-",4, width, flags);return;}if(value > DBL_MAX){out_rev_(output,(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.#ifdefPKG_VSNPRINTF_SUPPORT_EXPONENTIAL_SPECIFIERSprint_exponential_number(output, value, precision, width, flags, buf, len);#endifreturn;}// set default precision, if not set explicitlyif(!(flags & FLAGS_PRECISION)){
precision = PKG_VSNPRINTF_DEFAULT_FLOAT_PRECISION;}// limit precision so that our integer holding the fractional part does not overflowwhile((len < PKG_VSNPRINTF_DECIMAL_BUFFER_SIZE)&&(precision > PRINTF_MAX_SUPPORTED_PRECISION)){
buf[len++]='0';// This respects the precision in terms of result length only
precision--;}#ifdefPKG_VSNPRINTF_SUPPORT_EXPONENTIAL_SPECIFIERSif(prefer_exponential)print_exponential_number(output, value, precision, width, flags, buf, len);else#endifprint_decimal_number(output, value, precision, width, flags, buf, len);}#endif// (PKG_VSNPRINTF_SUPPORT_DECIMAL_SPECIFIERS || PKG_VSNPRINTF_SUPPORT_EXPONENTIAL_SPECIFIERS)// Advances the format pointer past the flags, and returns the parsed flags// due to the characters passedstaticprintf_flags_tparse_flags(constchar** 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);}staticinlinevoidformat_string_loop(output_gadget_t* output,constchar* format, va_list args){#ifdefPKG_VSNPRINTF_CHECK_FOR_NUL_IN_FORMAT_SPECIFIER#defineADVANCE_IN_FORMAT_STRING(cptr_)do{(cptr_)++;if(!*(cptr_))return;}while(0)#else#defineADVANCE_IN_FORMAT_STRING(cptr_)(cptr_)++#endifwhile(*format){if(*format !='%'){// A regular content characterputchar_via_gadget(output,*format);
format++;continue;}// We're parsing a format specifier: %[flags][width][.precision][length]ADVANCE_IN_FORMAT_STRING(format);printf_flags_t flags =parse_flags(&format);// evaluate width fieldprintf_size_t width =0U;if(is_digit_(*format)){
width =(printf_size_t)atou_(&format);}elseif(*format =='*'){constint w =va_arg(args,int);if(w <0){
flags |= FLAGS_LEFT;// reverse padding
width =(printf_size_t)-w;}else{
width =(printf_size_t)w;}ADVANCE_IN_FORMAT_STRING(format);}// evaluate precision fieldprintf_size_t precision =0U;if(*format =='.'){
flags |= FLAGS_PRECISION;ADVANCE_IN_FORMAT_STRING(format);if(is_digit_(*format)){
precision =(printf_size_t)atou_(&format);}elseif(*format =='*'){constint precision_ =va_arg(args,int);
precision = precision_ >0?(printf_size_t) precision_ :0U;ADVANCE_IN_FORMAT_STRING(format);}}// evaluate length fieldswitch(*format){#ifdefPKG_VSNPRINTF_SUPPORT_MSVC_STYLE_INTEGER_SPECIFIERScase'I':{ADVANCE_IN_FORMAT_STRING(format);// Greedily parse for size in bits: 8, 16, 32 or 64switch(*format){case'8': flags |= FLAGS_INT8;ADVANCE_IN_FORMAT_STRING(format);break;case'1':ADVANCE_IN_FORMAT_STRING(format);if(*format =='6'){ format++; flags |= FLAGS_INT16;}break;case'3':ADVANCE_IN_FORMAT_STRING(format);if(*format =='2'){ADVANCE_IN_FORMAT_STRING(format); flags |= FLAGS_INT32;}break;case'6':ADVANCE_IN_FORMAT_STRING(format);if(*format =='4'){ADVANCE_IN_FORMAT_STRING(format); flags |= FLAGS_INT64;}break;default:break;}break;}#endifcase'l':
flags |= FLAGS_LONG;ADVANCE_IN_FORMAT_STRING(format);if(*format =='l'){
flags |= FLAGS_LONG_LONG;ADVANCE_IN_FORMAT_STRING(format);}break;case'h':
flags |= FLAGS_SHORT;ADVANCE_IN_FORMAT_STRING(format);if(*format =='h'){
flags |= FLAGS_CHAR;ADVANCE_IN_FORMAT_STRING(format);}break;case't':
flags |=(sizeof(ptrdiff_t)==sizeof(long)? FLAGS_LONG : FLAGS_LONG_LONG);ADVANCE_IN_FORMAT_STRING(format);break;case'j':
flags |=(sizeof(intmax_t)==sizeof(long)? FLAGS_LONG : FLAGS_LONG_LONG);ADVANCE_IN_FORMAT_STRING(format);break;case'z':
flags |=(sizeof(size_t)==sizeof(long)? FLAGS_LONG : FLAGS_LONG_LONG);ADVANCE_IN_FORMAT_STRING(format);break;default:break;}// evaluate specifierswitch(*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;}elseif(*format =='o'){
base = BASE_OCTAL;}elseif(*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 givenif(flags & FLAGS_PRECISION){
flags &=~FLAGS_ZEROPAD;}if(flags & FLAGS_SIGNED){// A signed specifier: d, i or possibly I + bit size if enabledif(flags & FLAGS_LONG_LONG){#ifdefPKG_VSNPRINTF_SUPPORT_LONG_LONGconstlonglong value =va_arg(args,longlong);print_integer(output,ABS_FOR_PRINTING(value), value <0, base, precision, width, flags);#endif}elseif(flags & FLAGS_LONG){constlong value =va_arg(args,long);print_integer(output,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)constint value =(flags & FLAGS_CHAR)?(signedchar)va_arg(args,int):(flags & FLAGS_SHORT)?(shortint)va_arg(args,int):va_arg(args,int);print_integer(output,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){#ifdefPKG_VSNPRINTF_SUPPORT_LONG_LONGprint_integer(output,(printf_unsigned_value_t)va_arg(args,unsignedlonglong), false, base, precision, width, flags);#endif}elseif(flags & FLAGS_LONG){print_integer(output,(printf_unsigned_value_t)va_arg(args,unsignedlong), false, base, precision, width, flags);}else{constunsignedint value =(flags & FLAGS_CHAR)?(unsignedchar)va_arg(args,unsignedint):(flags & FLAGS_SHORT)?(unsignedshortint)va_arg(args,unsignedint):va_arg(args,unsignedint);print_integer(output,(printf_unsigned_value_t) value, false, base, precision, width, flags);}}break;}#ifdefPKG_VSNPRINTF_SUPPORT_DECIMAL_SPECIFIERScase'f':case'F':if(*format =='F') flags |= FLAGS_UPPERCASE;print_floating_point(output,va_arg(args,double), precision, width, flags, PRINTF_PREFER_DECIMAL);
format++;break;#endif#ifdefPKG_VSNPRINTF_SUPPORT_EXPONENTIAL_SPECIFIERScase'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,va_arg(args,double), precision, width, flags, PRINTF_PREFER_EXPONENTIAL);
format++;break;#endif// PKG_VSNPRINTF_SUPPORT_EXPONENTIAL_SPECIFIERScase'c':{printf_size_t l =1U;// pre paddingif(!(flags & FLAGS_LEFT)){while(l++< width){putchar_via_gadget(output,' ');}}// char outputputchar_via_gadget(output,(char)va_arg(args,int));// post paddingif(flags & FLAGS_LEFT){while(l++< width){putchar_via_gadget(output,' ');}}
format++;break;}case's':{constchar* p =va_arg(args,char*);if(p ==NULL){out_rev_(output,")llun(",6, width, flags);}else{printf_size_t l =strnlen_s_(p, precision ? precision : PRINTF_MAX_POSSIBLE_BUFFER_SIZE);// pre paddingif(flags & FLAGS_PRECISION){
l =(l < precision ? l : precision);}if(!(flags & FLAGS_LEFT)){while(l++< width){putchar_via_gadget(output,' ');}}// string outputwhile((*p !=0)&&(!(flags & FLAGS_PRECISION)|| precision)){putchar_via_gadget(output,*(p++));--precision;}// post paddingif(flags & FLAGS_LEFT){while(l++< width){putchar_via_gadget(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,")lin(",5, width, flags):print_integer(output,(printf_unsigned_value_t) value, false, BASE_HEX, precision, width, flags);
format++;break;}case'%':putchar_via_gadget(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.#ifdefPKG_VSNPRINTF_SUPPORT_WRITEBACK_SPECIFIERcase'n':{if(flags & FLAGS_CHAR)*(va_arg(args,char*))=(char) output->pos;elseif(flags & FLAGS_SHORT)*(va_arg(args,short*))=(short) output->pos;elseif(flags & FLAGS_LONG)*(va_arg(args,long*))=(long) output->pos;#ifdefPKG_VSNPRINTF_SUPPORT_LONG_LONGelseif(flags & FLAGS_LONG_LONG)*(va_arg(args,longlong*))=(longlongint) output->pos;#endif// PKG_VSNPRINTF_SUPPORT_LONG_LONGelse*(va_arg(args,int*))=(int) output->pos;
format++;break;}#endif// PKG_VSNPRINTF_SUPPORT_WRITEBACK_SPECIFIERdefault:putchar_via_gadget(output,*format);
format++;break;}}}// internal vsnprintf - used for implementing _all library functionsstaticintvsnprintf_impl(output_gadget_t* output,constchar* format, va_list args){// Note: The library only calls vsnprintf_impl() with output->pos being 0. However, it is// possible to call this function with a non-zero pos value for some "remedial printing".format_string_loop(output, format, args);// terminationappend_termination_with_gadget(output);// return written chars without terminating \0return(int)output->pos;}////**
* This function will fill a formatted string to buffer.
*
* @param buf is the buffer to save formatted string.
*
* @param size is the size of buffer.
*
* @param fmt is the format parameters.
*
* @param args is a list of variable parameters.
*
* @return The number of characters actually written to buffer.
*/#if(RTTHREAD_VERSION >=40100)||(RTTHREAD_VERSION <40000&& RTTHREAD_VERSION >=30106)intrt_vsnprintf(char*buf,rt_size_t size,constchar*fmt, va_list args)#elsert_int32_trt_vsnprintf(char*buf,rt_size_t size,constchar*fmt, va_list args)#endif{output_gadget_t gadget =buffer_gadget(buf, size);returnvsnprintf_impl(&gadget, fmt, args);}#ifdefRT_VSNPRINTF_FULL_REPLACING_VSNPRINTFintvsnprintf(char* s,size_t n,constchar* format, va_list arg){returnrt_vsnprintf(s, n, format, arg);}#endif#ifdefRT_VSNPRINTF_FULL_REPLACING_VSPRINTFintvsprintf(char* s,constchar* format, va_list arg){returnrt_vsprintf(s, format, arg);}#endif
总的来说这个问题都是 config 配置文件没有修改正确
一般修改数据库的用户名和密码与 phpstudy 一致并且添加了 key 就能初始化成功的 但是我还遇到过另一种情况，修改了上面的东西依旧无法连接到数据库
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