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libkernaux/src/printf.c

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/**
* The code was taken from Marco Paland's printf.
*
* Copyright (c) 2014-2019 Marco Paland <info@paland.com>
* Copyright (c) 2021-2022 Alex Kotov
*
* Tiny [v]fprintf, sfprintf and [v]snprintf implementation, optimized for speed
* on embedded systems with a very limited resources. These routines are thread
* safe and reentrant!
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <kernaux/assert.h>
#include <kernaux/generic/file.h>
#include <kernaux/printf.h>
#include <kernaux/printf_fmt.h>
#include "libc.h"
#include <stdbool.h>
#include <stdint.h>
// import float.h for DBL_MAX
#ifdef ENABLE_FLOAT
#include <float.h>
#endif
// 'ntoa' conversion buffer size, this must be big enough to hold one converted
// numeric number including padded zeros (dynamically created on stack)
#define PRINTF_NTOA_BUFFER_SIZE 32u
// 'ftoa' conversion buffer size, this must be big enough to hold one converted
// float number including padded zeros (dynamically created on stack)
#define PRINTF_FTOA_BUFFER_SIZE 32u
// define the default floating point precision
#define PRINTF_DEFAULT_FLOAT_PRECISION 6u
// define the largest float suitable to print with %f
#define PRINTF_MAX_FLOAT 1e9
// output function type
typedef void (*out_fct_type)(char character, void* buffer, size_t idx, size_t maxlen);
// wrapper (used as buffer) for output function type
typedef struct {
void (*fct)(char character, void* arg);
void* arg;
} out_fct_wrap_type;
static int _vsnprintf(out_fct_type out, char* buffer, const size_t maxlen, const char* format, va_list va);
static void file_putc(char c, void *arg);
static inline void _out_buffer(char character, void* buffer, size_t idx, size_t maxlen);
static inline void _out_null(char character, void* buffer, size_t idx, size_t maxlen);
static inline void _out_fct(char character, void* buffer, size_t idx, size_t maxlen);
static size_t _out_rev(out_fct_type out, char* buffer, size_t idx, size_t maxlen, const char* buf, size_t len, unsigned int width, unsigned int flags);
static size_t _ntoa_format(out_fct_type out, char* buffer, size_t idx, size_t maxlen, char* buf, size_t len, bool negative, unsigned int base, unsigned int prec, unsigned int width, unsigned int flags);
static size_t _ntoa_long(out_fct_type out, char* buffer, size_t idx, size_t maxlen, unsigned long value, bool negative, unsigned long base, unsigned int prec, unsigned int width, unsigned int flags);
static size_t _ntoa_long_long(out_fct_type out, char* buffer, size_t idx, size_t maxlen, unsigned long long value, bool negative, unsigned long long base, unsigned int prec, unsigned int width, unsigned int flags);
#ifdef ENABLE_FLOAT
static size_t _ftoa(out_fct_type out, char* buffer, size_t idx, size_t maxlen, double value, unsigned int prec, unsigned int width, unsigned int flags);
static size_t _etoa(out_fct_type out, char* buffer, size_t idx, size_t maxlen, double value, unsigned int prec, unsigned int width, unsigned int flags);
#endif // ENABLE_FLOAT
/*****************************
* Implementations: main API *
*****************************/
int kernaux_fprintf(const KernAux_File file, const char* format, ...)
{
KERNAUX_ASSERT(file);
KERNAUX_ASSERT(format);
va_list va;
va_start(va, format);
const out_fct_wrap_type out_fct_wrap = { file_putc, (void*)file };
const int ret = _vsnprintf(_out_fct, (char*)(uintptr_t)&out_fct_wrap, (size_t)-1, format, va);
va_end(va);
return ret;
}
int kernaux_vfprintf(const KernAux_File file, const char* format, va_list va)
{
KERNAUX_ASSERT(file);
KERNAUX_ASSERT(format);
const out_fct_wrap_type out_fct_wrap = { file_putc, (void*)file };
return _vsnprintf(_out_fct, (char*)(uintptr_t)&out_fct_wrap, (size_t)-1, format, va);
}
int kernaux_snprintf(char* buffer, size_t count, const char* format, ...)
{
KERNAUX_ASSERT(buffer);
KERNAUX_ASSERT(format);
va_list va;
va_start(va, format);
const int ret = _vsnprintf(_out_buffer, buffer, count, format, va);
va_end(va);
return ret;
}
int kernaux_vsnprintf(char* buffer, size_t count, const char* format, va_list va)
{
KERNAUX_ASSERT(buffer);
KERNAUX_ASSERT(format);
return _vsnprintf(_out_buffer, buffer, count, format, va);
}
int kernaux_sprintf(char* buffer, const char* format, ...)
{
KERNAUX_ASSERT(buffer);
KERNAUX_ASSERT(format);
va_list va;
va_start(va, format);
const int ret = _vsnprintf(_out_buffer, buffer, (size_t)-1, format, va);
va_end(va);
return ret;
}
/***************************
* Implementation: file IO *
***************************/
void file_putc(const char c, void *const arg)
{
KernAux_File file = arg;
KernAux_File_putc(file, c);
}
/******************************************
* Implementation: main internal function *
******************************************/
int _vsnprintf(out_fct_type out, char* buffer, const size_t maxlen, const char* format, va_list va)
{
KERNAUX_ASSERT(format);
size_t idx = 0u;
if (!buffer) {
// use null output function
out = _out_null;
}
while (*format)
{
// format specifier? %[flags][width][.precision][length]
if (*format != '%') {
// no
out(*format, buffer, idx++, maxlen);
format++;
continue;
} else {
// yes, evaluate it
format++;
}
struct KernAux_PrintfFmt_Spec spec = KernAux_PrintfFmt_Spec_create();
format = KernAux_PrintfFmt_Spec_parse(&spec, format);
if (spec.set_width) {
KernAux_PrintfFmt_Spec_set_width(&spec, va_arg(va, int));
}
if (spec.set_precision) {
KernAux_PrintfFmt_Spec_set_precision(&spec, va_arg(va, int));
}
// evaluate specifier
switch (spec.type) {
case KERNAUX_PRINTF_FMT_TYPE_INT:
if (spec.flags & KERNAUX_PRINTF_FMT_FLAGS_LONG_LONG) {
const long long value = va_arg(va, long long);
idx = _ntoa_long_long(out, buffer, idx, maxlen, (unsigned long long)(value > 0 ? value : 0 - value), value < 0, spec.base, spec.precision, spec.width, spec.flags);
} else if (spec.flags & KERNAUX_PRINTF_FMT_FLAGS_LONG) {
const long value = va_arg(va, long);
idx = _ntoa_long(out, buffer, idx, maxlen, (unsigned long)(value > 0 ? value : 0 - value), value < 0, spec.base, spec.precision, spec.width, spec.flags);
} else {
const int value = (spec.flags & KERNAUX_PRINTF_FMT_FLAGS_CHAR) ? (char)va_arg(va, int) : (spec.flags & KERNAUX_PRINTF_FMT_FLAGS_SHORT) ? (short int)va_arg(va, int) : va_arg(va, int);
idx = _ntoa_long(out, buffer, idx, maxlen, (unsigned int)(value > 0 ? value : 0 - value), value < 0, spec.base, spec.precision, spec.width, spec.flags);
}
break;
case KERNAUX_PRINTF_FMT_TYPE_UINT:
if (spec.flags & KERNAUX_PRINTF_FMT_FLAGS_LONG_LONG) {
idx = _ntoa_long_long(out, buffer, idx, maxlen, va_arg(va, unsigned long long), false, spec.base, spec.precision, spec.width, spec.flags);
} else if (spec.flags & KERNAUX_PRINTF_FMT_FLAGS_LONG) {
idx = _ntoa_long(out, buffer, idx, maxlen, va_arg(va, unsigned long), false, spec.base, spec.precision, spec.width, spec.flags);
} else {
const unsigned int value = (spec.flags & KERNAUX_PRINTF_FMT_FLAGS_CHAR) ? (unsigned char)va_arg(va, unsigned int) : (spec.flags & KERNAUX_PRINTF_FMT_FLAGS_SHORT) ? (unsigned short int)va_arg(va, unsigned int) : va_arg(va, unsigned int);
idx = _ntoa_long(out, buffer, idx, maxlen, value, false, spec.base, spec.precision, spec.width, spec.flags);
}
break;
#ifdef ENABLE_FLOAT
case KERNAUX_PRINTF_FMT_TYPE_FLOAT:
idx = _ftoa(out, buffer, idx, maxlen, va_arg(va, double), spec.precision, spec.width, spec.flags);
break;
case KERNAUX_PRINTF_FMT_TYPE_EXP:
idx = _etoa(out, buffer, idx, maxlen, va_arg(va, double), spec.precision, spec.width, spec.flags);
break;
#endif // ENABLE_FLOAT
case KERNAUX_PRINTF_FMT_TYPE_CHAR:
{
unsigned int l = 1u;
// pre padding
if (!(spec.flags & KERNAUX_PRINTF_FMT_FLAGS_LEFT)) {
while (l++ < spec.width) {
out(' ', buffer, idx++, maxlen);
}
}
// char output
out((char)va_arg(va, int), buffer, idx++, maxlen);
// post padding
if (spec.flags & KERNAUX_PRINTF_FMT_FLAGS_LEFT) {
while (l++ < spec.width) {
out(' ', buffer, idx++, maxlen);
}
}
break;
}
case KERNAUX_PRINTF_FMT_TYPE_STR:
{
const char* p = va_arg(va, char*);
unsigned int l = strnlen(p, spec.precision ? spec.precision : (size_t)-1);
// pre padding
if (spec.flags & KERNAUX_PRINTF_FMT_FLAGS_PRECISION) {
l = (l < spec.precision ? l : spec.precision);
}
if (!(spec.flags & KERNAUX_PRINTF_FMT_FLAGS_LEFT)) {
while (l++ < spec.width) {
out(' ', buffer, idx++, maxlen);
}
}
// string output
while ((*p != 0) && (!(spec.flags & KERNAUX_PRINTF_FMT_FLAGS_PRECISION) || spec.precision--)) {
out(*(p++), buffer, idx++, maxlen);
}
// post padding
if (spec.flags & KERNAUX_PRINTF_FMT_FLAGS_LEFT) {
while (l++ < spec.width) {
out(' ', buffer, idx++, maxlen);
}
}
break;
}
case KERNAUX_PRINTF_FMT_TYPE_PTR:
{
const bool is_ll = sizeof(uintptr_t) == sizeof(long long);
if (is_ll) {
idx = _ntoa_long_long(out, buffer, idx, maxlen, (uintptr_t)va_arg(va, void*), false, 16u, spec.precision, spec.width, spec.flags);
} else {
idx = _ntoa_long(out, buffer, idx, maxlen, (unsigned long)((uintptr_t)va_arg(va, void*)), false, 16u, spec.precision, spec.width, spec.flags);
}
break;
}
case KERNAUX_PRINTF_FMT_TYPE_PERCENT:
out('%', buffer, idx++, maxlen);
break;
default:
out(*format, buffer, idx++, maxlen);
++format;
break;
}
}
// termination
out((char)0, buffer, idx < maxlen ? idx : maxlen - 1u, maxlen);
// return written chars without terminating \0
return (int)idx;
}
/*************************************
* Implementations: helper functions *
*************************************/
// internal buffer output
void _out_buffer(char character, void* buffer, size_t idx, size_t maxlen)
{
if (idx < maxlen) {
((char*)buffer)[idx] = character;
}
}
// internal null output
void _out_null(char character, void* buffer, size_t idx, size_t maxlen)
{
(void)character; (void)buffer; (void)idx; (void)maxlen;
}
// internal output function wrapper
void _out_fct(char character, void* buffer, size_t idx, size_t maxlen)
{
(void)idx; (void)maxlen;
if (character) {
// buffer is the output fct pointer
((out_fct_wrap_type*)buffer)->fct(character, ((out_fct_wrap_type*)buffer)->arg);
}
}
// output the specified string in reverse, taking care of any zero-padding
size_t _out_rev(out_fct_type out, char* buffer, size_t idx, size_t maxlen, const char* buf, size_t len, unsigned int width, unsigned int flags)
{
const size_t start_idx = idx;
// pad spaces up to given width
if (!(flags & KERNAUX_PRINTF_FMT_FLAGS_LEFT) && !(flags & KERNAUX_PRINTF_FMT_FLAGS_ZEROPAD)) {
for (size_t i = len; i < width; i++) {
out(' ', buffer, idx++, maxlen);
}
}
// reverse string
while (len) {
out(buf[--len], buffer, idx++, maxlen);
}
// append pad spaces up to given width
if (flags & KERNAUX_PRINTF_FMT_FLAGS_LEFT) {
while (idx - start_idx < width) {
out(' ', buffer, idx++, maxlen);
}
}
return idx;
}
// internal itoa format
size_t _ntoa_format(out_fct_type out, char* buffer, size_t idx, size_t maxlen, char* buf, size_t len, bool negative, unsigned int base, unsigned int prec, unsigned int width, unsigned int flags)
{
// pad leading zeros
if (!(flags & KERNAUX_PRINTF_FMT_FLAGS_LEFT)) {
if (width && (flags & KERNAUX_PRINTF_FMT_FLAGS_ZEROPAD) && (negative || (flags & (KERNAUX_PRINTF_FMT_FLAGS_PLUS | KERNAUX_PRINTF_FMT_FLAGS_SPACE)))) {
width--;
}
while ((len < prec) && (len < PRINTF_NTOA_BUFFER_SIZE)) {
buf[len++] = '0';
}
while ((flags & KERNAUX_PRINTF_FMT_FLAGS_ZEROPAD) && (len < width) && (len < PRINTF_NTOA_BUFFER_SIZE)) {
buf[len++] = '0';
}
}
// handle hash
if (flags & KERNAUX_PRINTF_FMT_FLAGS_HASH) {
if (!(flags & KERNAUX_PRINTF_FMT_FLAGS_PRECISION) && len && ((len == prec) || (len == width))) {
len--;
if (len && (base == 16u)) {
len--;
}
}
if ((base == 16u) && !(flags & KERNAUX_PRINTF_FMT_FLAGS_UPPERCASE) && (len < PRINTF_NTOA_BUFFER_SIZE)) {
buf[len++] = 'x';
} else if ((base == 16u) && (flags & KERNAUX_PRINTF_FMT_FLAGS_UPPERCASE) && (len < PRINTF_NTOA_BUFFER_SIZE)) {
buf[len++] = 'X';
} else if ((base == 2u) && (len < PRINTF_NTOA_BUFFER_SIZE)) {
buf[len++] = 'b';
}
if (len < PRINTF_NTOA_BUFFER_SIZE) {
buf[len++] = '0';
}
}
if (len < PRINTF_NTOA_BUFFER_SIZE) {
if (negative) {
buf[len++] = '-';
} else if (flags & KERNAUX_PRINTF_FMT_FLAGS_PLUS) {
buf[len++] = '+'; // ignore the space if the '+' exists
} else if (flags & KERNAUX_PRINTF_FMT_FLAGS_SPACE) {
buf[len++] = ' ';
}
}
return _out_rev(out, buffer, idx, maxlen, buf, len, width, flags);
}
// internal itoa for 'long' type
size_t _ntoa_long(out_fct_type out, char* buffer, size_t idx, size_t maxlen, unsigned long value, bool negative, unsigned long base, unsigned int prec, unsigned int width, unsigned int flags)
{
char buf[PRINTF_NTOA_BUFFER_SIZE];
size_t len = 0u;
// no hash for 0 values
if (!value) {
flags &= ~KERNAUX_PRINTF_FMT_FLAGS_HASH;
}
// write if precision != 0 and value is != 0
if (!(flags & KERNAUX_PRINTF_FMT_FLAGS_PRECISION) || value) {
do {
const char digit = (char)(value % base);
buf[len++] = digit < 10 ? '0' + digit : ((flags & KERNAUX_PRINTF_FMT_FLAGS_UPPERCASE) ? 'A' : 'a') + digit - 10;
value /= base;
} while (value && (len < PRINTF_NTOA_BUFFER_SIZE));
}
return _ntoa_format(out, buffer, idx, maxlen, buf, len, negative, (unsigned int)base, prec, width, flags);
}
// internal itoa for 'long long' type
size_t _ntoa_long_long(out_fct_type out, char* buffer, size_t idx, size_t maxlen, unsigned long long value, bool negative, unsigned long long base, unsigned int prec, unsigned int width, unsigned int flags)
{
char buf[PRINTF_NTOA_BUFFER_SIZE];
size_t len = 0u;
// no hash for 0 values
if (!value) {
flags &= ~KERNAUX_PRINTF_FMT_FLAGS_HASH;
}
// write if precision != 0 and value is != 0
if (!(flags & KERNAUX_PRINTF_FMT_FLAGS_PRECISION) || value) {
do {
const char digit = (char)(value % base);
buf[len++] = digit < 10 ? '0' + digit : ((flags & KERNAUX_PRINTF_FMT_FLAGS_UPPERCASE) ? 'A' : 'a') + digit - 10;
value /= base;
} while (value && (len < PRINTF_NTOA_BUFFER_SIZE));
}
return _ntoa_format(out, buffer, idx, maxlen, buf, len, negative, (unsigned int)base, prec, width, flags);
}
#ifdef ENABLE_FLOAT
// internal ftoa for fixed decimal floating point
size_t _ftoa(out_fct_type out, char* buffer, size_t idx, size_t maxlen, double value, unsigned int prec, unsigned int width, unsigned int flags)
{
char buf[PRINTF_FTOA_BUFFER_SIZE];
size_t len = 0u;
double diff = 0.0;
// powers of 10
static const double pow10[] = { 1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000 };
// test for special values
if (value != value)
return _out_rev(out, buffer, idx, maxlen, "nan", 3, width, flags);
if (value < -DBL_MAX)
return _out_rev(out, buffer, idx, maxlen, "fni-", 4, width, flags);
if (value > DBL_MAX)
return _out_rev(out, buffer, idx, maxlen, (flags & KERNAUX_PRINTF_FMT_FLAGS_PLUS) ? "fni+" : "fni", (flags & KERNAUX_PRINTF_FMT_FLAGS_PLUS) ? 4u : 3u, width, flags);
// test for very large values
// standard printf behavior is to print EVERY whole number digit -- which could be 100s of characters overflowing your buffers == bad
if ((value > PRINTF_MAX_FLOAT) || (value < -PRINTF_MAX_FLOAT)) {
return _etoa(out, buffer, idx, maxlen, value, prec, width, flags);
}
// test for negative
bool negative = false;
if (value < 0) {
negative = true;
value = 0 - value;
}
// set default precision, if not set explicitly
if (!(flags & KERNAUX_PRINTF_FMT_FLAGS_PRECISION)) {
prec = PRINTF_DEFAULT_FLOAT_PRECISION;
}
// limit precision to 9, cause a prec >= 10 can lead to overflow errors
while ((len < PRINTF_FTOA_BUFFER_SIZE) && (prec > 9u)) {
buf[len++] = '0';
prec--;
}
int whole = (int)value;
double tmp = (value - whole) * pow10[prec];
unsigned long frac = (unsigned long)tmp;
diff = tmp - frac;
if (diff > 0.5) {
++frac;
// handle rollover, e.g. case 0.99 with prec 1 is 1.0
if (frac >= pow10[prec]) {
frac = 0;
++whole;
}
} else if (diff < 0.5) {
// TODO: do nothing?
} else if ((frac == 0u) || (frac & 1u)) {
// if halfway, round up if odd OR if last digit is 0
++frac;
}
if (prec == 0u) {
diff = value - (double)whole;
if ((!(diff < 0.5) || (diff > 0.5)) && (whole & 1)) {
// exactly 0.5 and ODD, then round up
// 1.5 -> 2, but 2.5 -> 2
++whole;
}
} else {
unsigned int count = prec;
// now do fractional part, as an unsigned number
while (len < PRINTF_FTOA_BUFFER_SIZE) {
--count;
buf[len++] = (char)(48u + (frac % 10u));
if (!(frac /= 10u)) {
break;
}
}
// add extra 0s
while ((len < PRINTF_FTOA_BUFFER_SIZE) && (count-- > 0u)) {
buf[len++] = '0';
}
if (len < PRINTF_FTOA_BUFFER_SIZE) {
// add decimal
buf[len++] = '.';
}
}
// do whole part, number is reversed
while (len < PRINTF_FTOA_BUFFER_SIZE) {
buf[len++] = (char)(48 + (whole % 10));
if (!(whole /= 10)) {
break;
}
}
// pad leading zeros
if (!(flags & KERNAUX_PRINTF_FMT_FLAGS_LEFT) && (flags & KERNAUX_PRINTF_FMT_FLAGS_ZEROPAD)) {
if (width && (negative || (flags & (KERNAUX_PRINTF_FMT_FLAGS_PLUS | KERNAUX_PRINTF_FMT_FLAGS_SPACE)))) {
width--;
}
while ((len < width) && (len < PRINTF_FTOA_BUFFER_SIZE)) {
buf[len++] = '0';
}
}
if (len < PRINTF_FTOA_BUFFER_SIZE) {
if (negative) {
buf[len++] = '-';
} else if (flags & KERNAUX_PRINTF_FMT_FLAGS_PLUS) {
buf[len++] = '+'; // ignore the space if the '+' exists
} else if (flags & KERNAUX_PRINTF_FMT_FLAGS_SPACE) {
buf[len++] = ' ';
}
}
return _out_rev(out, buffer, idx, maxlen, buf, len, width, flags);
}
// internal ftoa variant for exponential floating-point type, contributed by Martijn Jasperse <m.jasperse@gmail.com>
size_t _etoa(out_fct_type out, char* buffer, size_t idx, size_t maxlen, double value, unsigned int prec, unsigned int width, unsigned int flags)
{
// check for NaN and special values
if ((value != value) || (value > DBL_MAX) || (value < -DBL_MAX)) {
return _ftoa(out, buffer, idx, maxlen, value, prec, width, flags);
}
// determine the sign
const bool negative = value < 0;
if (negative) {
value = -value;
}
// default precision
if (!(flags & KERNAUX_PRINTF_FMT_FLAGS_PRECISION)) {
prec = PRINTF_DEFAULT_FLOAT_PRECISION;
}
// determine the decimal exponent
// based on the algorithm by David Gay (https://www.ampl.com/netlib/fp/dtoa.c)
union {
uint64_t U;
double F;
} conv;
conv.F = value;
int exp2 = (int)((conv.U >> 52u) & 0x07ffu) - 1023; // effectively log2
conv.U = (conv.U & ((1ull << 52u) - 1u)) | (102ull << 52u); // drop the exponent so conv.F is now in [1,2)
// now approximate log10 from the log2 integer part and an expansion of ln around 1.5
int expval = (int)(0.1760912590558 + exp2 * 0.301029995663981 + (conv.F - 1.5) * 0.289529654602168);
// now we want to compute 10^expval but we want to be sure it won't overflow
exp2 = (int)(expval * 3.321928094887362 + 0.5);
const double z = expval * 2.302585092994046 - exp2 * 0.6931471805599453;
const double z2 = z * z;
conv.U = (uint64_t)(exp2 + 1023) << 52u;
// compute exp(z) using continued fractions, see https://en.wikipedia.org/wiki/Exponential_function#Continued_fractions_for_ex
conv.F *= 1 + 2 * z / (2 - z + (z2 / (6 + (z2 / (10 + z2 / 14)))));
// correct for rounding errors
if (value < conv.F) {
expval--;
conv.F /= 10;
}
// the exponent format is "%+03d" and largest value is "307", so set aside 4-5 characters
unsigned int minwidth = ((expval < 100) && (expval > -100)) ? 4u : 5u;
// in "%g" mode, "prec" is the number of *significant figures* not decimals
if (flags & KERNAUX_PRINTF_FMT_FLAGS_ADAPT_EXP) {
// do we want to fall-back to "%f" mode?
if ((value >= 1e-4) && (value < 1e6)) {
if ((int)prec > expval) {
prec = (unsigned)((int)prec - expval - 1);
} else {
prec = 0;
}
flags |= KERNAUX_PRINTF_FMT_FLAGS_PRECISION; // make sure _ftoa respects precision
// no characters in exponent
minwidth = 0u;
expval = 0;
} else {
// we use one sigfig for the whole part
if ((prec > 0) && (flags & KERNAUX_PRINTF_FMT_FLAGS_PRECISION)) {
--prec;
}
}
}
// will everything fit?
unsigned int fwidth = width;
if (width > minwidth) {
// we didn't fall-back so subtract the characters required for the exponent
fwidth -= minwidth;
} else {
// not enough characters, so go back to default sizing
fwidth = 0u;
}
if ((flags & KERNAUX_PRINTF_FMT_FLAGS_LEFT) && minwidth) {
// if we're padding on the right, DON'T pad the floating part
fwidth = 0u;
}
// rescale the float value
if (expval) {
value /= conv.F;
}
// output the floating part
const size_t start_idx = idx;
idx = _ftoa(out, buffer, idx, maxlen, negative ? -value : value, prec, fwidth, flags & ~KERNAUX_PRINTF_FMT_FLAGS_ADAPT_EXP);
// output the exponent part
if (minwidth) {
// output the exponential symbol
out((flags & KERNAUX_PRINTF_FMT_FLAGS_UPPERCASE) ? 'E' : 'e', buffer, idx++, maxlen);
// output the exponent value
idx = _ntoa_long(out, buffer, idx, maxlen, (expval < 0) ? -expval : expval, expval < 0, 10, 0, minwidth-1, KERNAUX_PRINTF_FMT_FLAGS_ZEROPAD | KERNAUX_PRINTF_FMT_FLAGS_PLUS);
// might need to right-pad spaces
if (flags & KERNAUX_PRINTF_FMT_FLAGS_LEFT) {
while (idx - start_idx < width) out(' ', buffer, idx++, maxlen);
}
}
return idx;
}
#endif // ENABLE_FLOAT
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