source: mainline/common/printf/printf_core.c@ ef4d684

/*
 * Copyright (c) 2001-2004 Jakub Jermar
 * Copyright (c) 2006 Josef Cejka
 * Copyright (c) 2009 Martin Decky
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup libc
 * @{
 */
/**
 * @file
 * @brief Printing functions.
 */

#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>
#include <printf_core.h>
#include <ctype.h>
#include <str.h>
#include <assert.h>
#include <macros.h>
#include <uchar.h>

/* Disable float support in kernel, because we usually disable floating operations there. */
#if __STDC_HOSTED__
#define HAS_FLOAT
#endif

#ifdef HAS_FLOAT
#include <double_to_str.h>
#include <ieee_double.h>
#endif

/** show prefixes 0x or 0 */
#define __PRINTF_FLAG_PREFIX       0x00000001

/** show the decimal point even if no fractional digits present */
#define __PRINTF_FLAG_DECIMALPT    0x00000001

/** signed / unsigned number */
#define __PRINTF_FLAG_SIGNED       0x00000002

/** print leading zeroes */
#define __PRINTF_FLAG_ZEROPADDED   0x00000004

/** align to left */
#define __PRINTF_FLAG_LEFTALIGNED  0x00000010

/** always show + sign */
#define __PRINTF_FLAG_SHOWPLUS     0x00000020

/** print space instead of plus */
#define __PRINTF_FLAG_SPACESIGN    0x00000040

/** show big characters */
#define __PRINTF_FLAG_BIGCHARS     0x00000080

/** number has - sign */
#define __PRINTF_FLAG_NEGATIVE     0x00000100

/** don't print trailing zeros in the fractional part */
#define __PRINTF_FLAG_NOFRACZEROS  0x00000200

/**
 * Buffer big enough for 64-bit number printed in base 2, sign, prefix and 0
 * to terminate string... (last one is only for better testing end of buffer by
 * zero-filling subroutine)
 */
#define PRINT_NUMBER_BUFFER_SIZE  (64 + 5)

/** Get signed or unsigned integer argument */
#define PRINTF_GET_INT_ARGUMENT(type, ap, flags) \
        ({ \
                unsigned type res; \
                \
                if ((flags) & __PRINTF_FLAG_SIGNED) { \
                        signed type arg = va_arg((ap), signed type); \
                        \
                        if (arg < 0) { \
                                res = -arg; \
                                (flags) |= __PRINTF_FLAG_NEGATIVE; \
                        } else \
                                res = arg; \
                } else \
                        res = va_arg((ap), unsigned type); \
                \
                res; \
        })

/** Enumeration of possible arguments types.
 */
typedef enum {
        PrintfQualifierByte = 0,
        PrintfQualifierShort,
        PrintfQualifierInt,
        PrintfQualifierLong,
        PrintfQualifierLongLong,
        PrintfQualifierPointer,
        PrintfQualifierSize,
        PrintfQualifierMax
} qualifier_t;

static const char *nullstr = "(NULL)";
static const char *digits_small = "0123456789abcdef";
static const char *digits_big = "0123456789ABCDEF";
static const char invalch = U_SPECIAL;

/** Print one or more characters without adding newline.
 *
 * @param buf  Buffer holding characters with size of
 *             at least size bytes. NULL is not allowed!
 * @param size Size of the buffer in bytes.
 * @param ps   Output method and its data.
 *
 * @return Number of characters printed.
 *
 */
static int printf_putnchars(const char *buf, size_t size,
    printf_spec_t *ps)
{
        return ps->str_write((void *) buf, size, ps->data);
}

/** Print one or more wide characters without adding newline.
 *
 * @param buf  Buffer holding wide characters with size of
 *             at least size bytes. NULL is not allowed!
 * @param size Size of the buffer in bytes.
 * @param ps   Output method and its data.
 *
 * @return Number of wide characters printed.
 *
 */
static int printf_wputnchars(const char32_t *buf, size_t size,
    printf_spec_t *ps)
{
        return ps->wstr_write((void *) buf, size, ps->data);
}

/** Print string without adding a newline.
 *
 * @param str String to print.
 * @param ps  Write function specification and support data.
 *
 * @return Number of characters printed.
 *
 */
static int printf_putstr(const char *str, printf_spec_t *ps)
{
        if (str == NULL)
                return printf_putnchars(nullstr, str_size(nullstr), ps);

        return ps->str_write((void *) str, str_size(str), ps->data);
}

/** Print one ASCII character.
 *
 * @param c  ASCII character to be printed.
 * @param ps Output method.
 *
 * @return Number of characters printed.
 *
 */
static int printf_putchar(const char ch, printf_spec_t *ps)
{
        if (!ascii_check(ch))
                return ps->str_write((void *) &invalch, 1, ps->data);

        return ps->str_write(&ch, 1, ps->data);
}

/** Print one wide character.
 *
 * @param c  Wide character to be printed.
 * @param ps Output method.
 *
 * @return Number of characters printed.
 *
 */
static int printf_putuchar(const char32_t ch, printf_spec_t *ps)
{
        if (!chr_check(ch))
                return ps->str_write((void *) &invalch, 1, ps->data);

        return ps->wstr_write(&ch, sizeof(char32_t), ps->data);
}

/** Print one formatted ASCII character.
 *
 * @param ch    Character to print.
 * @param width Width modifier.
 * @param flags Flags that change the way the character is printed.
 *
 * @return Number of characters printed, negative value on failure.
 *
 */
static int print_char(const char ch, int width, uint32_t flags, printf_spec_t *ps)
{
        size_t counter = 0;
        if (!(flags & __PRINTF_FLAG_LEFTALIGNED)) {
                while (--width > 0) {
                        /*
                         * One space is consumed by the character itself, hence
                         * the predecrement.
                         */
                        if (printf_putchar(' ', ps) > 0)
                                counter++;
                }
        }

        if (printf_putchar(ch, ps) > 0)
                counter++;

        while (--width > 0) {
                /*
                 * One space is consumed by the character itself, hence
                 * the predecrement.
                 */
                if (printf_putchar(' ', ps) > 0)
                        counter++;
        }

        return (int) (counter);
}

/** Print one formatted wide character.
 *
 * @param ch    Character to print.
 * @param width Width modifier.
 * @param flags Flags that change the way the character is printed.
 *
 * @return Number of characters printed, negative value on failure.
 *
 */
static int print_wchar(const char32_t ch, int width, uint32_t flags, printf_spec_t *ps)
{
        size_t counter = 0;
        if (!(flags & __PRINTF_FLAG_LEFTALIGNED)) {
                while (--width > 0) {
                        /*
                         * One space is consumed by the character itself, hence
                         * the predecrement.
                         */
                        if (printf_putchar(' ', ps) > 0)
                                counter++;
                }
        }

        if (printf_putuchar(ch, ps) > 0)
                counter++;

        while (--width > 0) {
                /*
                 * One space is consumed by the character itself, hence
                 * the predecrement.
                 */
                if (printf_putchar(' ', ps) > 0)
                        counter++;
        }

        return (int) (counter);
}

/** Print string.
 *
 * @param str       String to be printed.
 * @param width     Width modifier.
 * @param precision Precision modifier.
 * @param flags     Flags that modify the way the string is printed.
 *
 * @return Number of characters printed, negative value on failure.
 */
static int print_str(char *str, int width, unsigned int precision,
    uint32_t flags, printf_spec_t *ps)
{
        if (str == NULL)
                return printf_putstr(nullstr, ps);

        size_t strw = str_length(str);

        /* Precision unspecified - print everything. */
        if ((precision == 0) || (precision > strw))
                precision = strw;

        /* Left padding */
        size_t counter = 0;
        width -= precision;
        if (!(flags & __PRINTF_FLAG_LEFTALIGNED)) {
                while (width-- > 0) {
                        if (printf_putchar(' ', ps) == 1)
                                counter++;
                }
        }

        /* Part of @a str fitting into the alloted space. */
        int retval;
        size_t size = str_lsize(str, precision);
        if ((retval = printf_putnchars(str, size, ps)) < 0)
                return -counter;

        counter += retval;

        /* Right padding */
        while (width-- > 0) {
                if (printf_putchar(' ', ps) == 1)
                        counter++;
        }

        return ((int) counter);

}

/** Print wide string.
 *
 * @param str       Wide string to be printed.
 * @param width     Width modifier.
 * @param precision Precision modifier.
 * @param flags     Flags that modify the way the string is printed.
 *
 * @return Number of wide characters printed, negative value on failure.
 */
static int print_wstr(char32_t *str, int width, unsigned int precision,
    uint32_t flags, printf_spec_t *ps)
{
        if (str == NULL)
                return printf_putstr(nullstr, ps);

        size_t strw = wstr_length(str);

        /* Precision not specified - print everything. */
        if ((precision == 0) || (precision > strw))
                precision = strw;

        /* Left padding */
        size_t counter = 0;
        width -= precision;
        if (!(flags & __PRINTF_FLAG_LEFTALIGNED)) {
                while (width-- > 0) {
                        if (printf_putchar(' ', ps) == 1)
                                counter++;
                }
        }

        /* Part of @a wstr fitting into the alloted space. */
        int retval;
        size_t size = wstr_lsize(str, precision);
        if ((retval = printf_wputnchars(str, size, ps)) < 0)
                return -counter;

        counter += retval;

        /* Right padding */
        while (width-- > 0) {
                if (printf_putchar(' ', ps) == 1)
                        counter++;
        }

        return ((int) counter);
}

/** Print a number in a given base.
 *
 * Print significant digits of a number in given base.
 *
 * @param num       Number to print.
 * @param width     Width modifier.
 * @param precision Precision modifier.
 * @param base      Base to print the number in (must be between 2 and 16).
 * @param flags     Flags that modify the way the number is printed.
 *
 * @return Number of characters printed.
 *
 */
static int print_number(uint64_t num, int width, int precision, int base,
    uint32_t flags, printf_spec_t *ps)
{
        /* Precision not specified. */
        if (precision < 0) {
                precision = 0;
        }

        const char *digits;
        if (flags & __PRINTF_FLAG_BIGCHARS)
                digits = digits_big;
        else
                digits = digits_small;

        char data[PRINT_NUMBER_BUFFER_SIZE];
        char *ptr = &data[PRINT_NUMBER_BUFFER_SIZE - 1];

        /* Size of number with all prefixes and signs */
        int size = 0;

        /* Put zero at end of string */
        *ptr-- = 0;

        if (num == 0) {
                *ptr-- = '0';
                size++;
        } else {
                do {
                        *ptr-- = digits[num % base];
                        size++;
                } while (num /= base);
        }

        /* Size of plain number */
        int number_size = size;

        /*
         * Collect the sum of all prefixes/signs/etc. to calculate padding and
         * leading zeroes.
         */
        if (flags & __PRINTF_FLAG_PREFIX) {
                switch (base) {
                case 2:
                        /* Binary formating is not standard, but usefull */
                        size += 2;
                        break;
                case 8:
                        size++;
                        break;
                case 16:
                        size += 2;
                        break;
                }
        }

        char sgn = 0;
        if (flags & __PRINTF_FLAG_SIGNED) {
                if (flags & __PRINTF_FLAG_NEGATIVE) {
                        sgn = '-';
                        size++;
                } else if (flags & __PRINTF_FLAG_SHOWPLUS) {
                        sgn = '+';
                        size++;
                } else if (flags & __PRINTF_FLAG_SPACESIGN) {
                        sgn = ' ';
                        size++;
                }
        }

        if (flags & __PRINTF_FLAG_LEFTALIGNED)
                flags &= ~__PRINTF_FLAG_ZEROPADDED;

        /*
         * If the number is left-aligned or precision is specified then
         * padding with zeros is ignored.
         */
        if (flags & __PRINTF_FLAG_ZEROPADDED) {
                if ((precision == 0) && (width > size))
                        precision = width - size + number_size;
        }

        /* Print leading spaces */
        if (number_size > precision) {
                /* Print the whole number, not only a part */
                precision = number_size;
        }

        width -= precision + size - number_size;
        size_t counter = 0;

        if (!(flags & __PRINTF_FLAG_LEFTALIGNED)) {
                while (width-- > 0) {
                        if (printf_putchar(' ', ps) == 1)
                                counter++;
                }
        }

        /* Print sign */
        if (sgn) {
                if (printf_putchar(sgn, ps) == 1)
                        counter++;
        }

        /* Print prefix */
        if (flags & __PRINTF_FLAG_PREFIX) {
                switch (base) {
                case 2:
                        /* Binary formating is not standard, but usefull */
                        if (printf_putchar('0', ps) == 1)
                                counter++;
                        if (flags & __PRINTF_FLAG_BIGCHARS) {
                                if (printf_putchar('B', ps) == 1)
                                        counter++;
                        } else {
                                if (printf_putchar('b', ps) == 1)
                                        counter++;
                        }
                        break;
                case 8:
                        if (printf_putchar('o', ps) == 1)
                                counter++;
                        break;
                case 16:
                        if (printf_putchar('0', ps) == 1)
                                counter++;
                        if (flags & __PRINTF_FLAG_BIGCHARS) {
                                if (printf_putchar('X', ps) == 1)
                                        counter++;
                        } else {
                                if (printf_putchar('x', ps) == 1)
                                        counter++;
                        }
                        break;
                }
        }

        /* Print leading zeroes */
        precision -= number_size;
        while (precision-- > 0) {
                if (printf_putchar('0', ps) == 1)
                        counter++;
        }

        /* Print the number itself */
        int retval;
        if ((retval = printf_putstr(++ptr, ps)) > 0)
                counter += retval;

        /* Print trailing spaces */

        while (width-- > 0) {
                if (printf_putchar(' ', ps) == 1)
                        counter++;
        }

        return ((int) counter);
}

#ifdef HAS_FLOAT

/** Unformatted double number string representation. */
typedef struct {
        /** Buffer with len digits, no sign or leading zeros. */
        char *str;
        /** Number of digits in str. */
        int len;
        /** Decimal exponent, ie number = str * 10^dec_exp */
        int dec_exp;
        /** True if negative. */
        bool neg;
} double_str_t;

/** Returns the sign character or 0 if no sign should be printed. */
static int get_sign_char(bool negative, uint32_t flags)
{
        if (negative) {
                return '-';
        } else if (flags & __PRINTF_FLAG_SHOWPLUS) {
                return '+';
        } else if (flags & __PRINTF_FLAG_SPACESIGN) {
                return ' ';
        } else {
                return 0;
        }
}

/** Prints count times character ch. */
static int print_padding(char ch, int count, printf_spec_t *ps)
{
        for (int i = 0; i < count; ++i) {
                if (ps->str_write(&ch, 1, ps->data) < 0) {
                        return -1;
                }
        }

        return count;
}

/** Prints a special double (ie NaN, infinity) padded to width characters. */
static int print_special(ieee_double_t val, int width, uint32_t flags,
    printf_spec_t *ps)
{
        assert(val.is_special);

        char sign = get_sign_char(val.is_negative, flags);

        const int str_len = 3;
        const char *str;

        if (flags & __PRINTF_FLAG_BIGCHARS) {
                str = val.is_infinity ? "INF" : "NAN";
        } else {
                str = val.is_infinity ? "inf" : "nan";
        }

        int padding_len = max(0, width - ((sign ? 1 : 0) + str_len));

        int counter = 0;
        int ret;

        /* Leading padding. */
        if (!(flags & __PRINTF_FLAG_LEFTALIGNED)) {
                if ((ret = print_padding(' ', padding_len, ps)) < 0)
                        return -1;

                counter += ret;
        }

        if (sign) {
                if ((ret = ps->str_write(&sign, 1, ps->data)) < 0)
                        return -1;

                counter += ret;
        }

        if ((ret = ps->str_write(str, str_len, ps->data)) < 0)
                return -1;

        counter += ret;

        /* Trailing padding. */
        if (flags & __PRINTF_FLAG_LEFTALIGNED) {
                if ((ret = print_padding(' ', padding_len, ps)) < 0)
                        return -1;

                counter += ret;
        }

        return counter;
}

/** Trims trailing zeros but leaves a single "0" intact. */
static void fp_trim_trailing_zeros(char *buf, int *len, int *dec_exp)
{
        /* Cut the zero off by adjusting the exponent. */
        while (2 <= *len && '0' == buf[*len - 1]) {
                --*len;
                ++*dec_exp;
        }
}

/** Textually round up the last digit thereby eliminating it. */
static void fp_round_up(char *buf, int *len, int *dec_exp)
{
        assert(1 <= *len);

        char *last_digit = &buf[*len - 1];

        int carry = ('5' <= *last_digit);

        /* Cut the digit off by adjusting the exponent. */
        --*len;
        ++*dec_exp;
        --last_digit;

        if (carry) {
                /* Skip all the digits to cut off/round to zero. */
                while (buf <= last_digit && '9' == *last_digit) {
                        --last_digit;
                }

                /* last_digit points to the last digit to round but not '9' */
                if (buf <= last_digit) {
                        *last_digit += 1;
                        int new_len = last_digit - buf + 1;
                        *dec_exp += *len - new_len;
                        *len = new_len;
                } else {
                        /* All len digits rounded to 0. */
                        buf[0] = '1';
                        *dec_exp += *len;
                        *len = 1;
                }
        } else {
                /* The only digit was rounded to 0. */
                if (last_digit < buf) {
                        buf[0] = '0';
                        *dec_exp = 0;
                        *len = 1;
                }
        }
}

/** Format and print the double string repressentation according
 *  to the %f specifier.
 */
static int print_double_str_fixed(double_str_t *val_str, int precision, int width,
    uint32_t flags, printf_spec_t *ps)
{
        int len = val_str->len;
        char *buf = val_str->str;
        int dec_exp = val_str->dec_exp;

        assert(0 < len);
        assert(0 <= precision);
        assert(0 <= dec_exp || -dec_exp <= precision);

        /* Number of integral digits to print (at least leading zero). */
        int int_len = max(1, len + dec_exp);

        char sign = get_sign_char(val_str->neg, flags);

        /* Fractional portion lengths. */
        int last_frac_signif_pos = max(0, -dec_exp);
        int leading_frac_zeros = max(0, last_frac_signif_pos - len);
        int signif_frac_figs = min(last_frac_signif_pos, len);
        int trailing_frac_zeros = precision - last_frac_signif_pos;
        char *buf_frac = buf + len - signif_frac_figs;

        if (flags & __PRINTF_FLAG_NOFRACZEROS) {
                trailing_frac_zeros = 0;
        }

        int frac_len = leading_frac_zeros + signif_frac_figs + trailing_frac_zeros;

        bool has_decimal_pt = (0 < frac_len) || (flags & __PRINTF_FLAG_DECIMALPT);

        /* Number of non-padding chars to print. */
        int num_len = (sign ? 1 : 0) + int_len + (has_decimal_pt ? 1 : 0) + frac_len;

        int padding_len = max(0, width - num_len);
        int ret = 0;
        int counter = 0;

        /* Leading padding and sign. */

        if (!(flags & (__PRINTF_FLAG_LEFTALIGNED | __PRINTF_FLAG_ZEROPADDED))) {
                if ((ret = print_padding(' ', padding_len, ps)) < 0)
                        return -1;

                counter += ret;
        }

        if (sign) {
                if ((ret = ps->str_write(&sign, 1, ps->data)) < 0)
                        return -1;

                counter += ret;
        }

        if (flags & __PRINTF_FLAG_ZEROPADDED) {
                if ((ret = print_padding('0', padding_len, ps)) < 0)
                        return -1;

                counter += ret;
        }

        /* Print the intergral part of the buffer. */

        int buf_int_len = min(len, len + dec_exp);

        if (0 < buf_int_len) {
                if ((ret = ps->str_write(buf, buf_int_len, ps->data)) < 0)
                        return -1;

                counter += ret;

                /* Print trailing zeros of the integral part of the number. */
                if ((ret = print_padding('0', int_len - buf_int_len, ps)) < 0)
                        return -1;
        } else {
                /* Single leading integer 0. */
                char ch = '0';
                if ((ret = ps->str_write(&ch, 1, ps->data)) < 0)
                        return -1;
        }

        counter += ret;

        /* Print the decimal point and the fractional part. */
        if (has_decimal_pt) {
                char ch = '.';

                if ((ret = ps->str_write(&ch, 1, ps->data)) < 0)
                        return -1;

                counter += ret;

                /* Print leading zeros of the fractional part of the number. */
                if ((ret = print_padding('0', leading_frac_zeros, ps)) < 0)
                        return -1;

                counter += ret;

                /* Print significant digits of the fractional part of the number. */
                if (0 < signif_frac_figs) {
                        if ((ret = ps->str_write(buf_frac, signif_frac_figs, ps->data)) < 0)
                                return -1;

                        counter += ret;
                }

                /* Print trailing zeros of the fractional part of the number. */
                if ((ret = print_padding('0', trailing_frac_zeros, ps)) < 0)
                        return -1;

                counter += ret;
        }

        /* Trailing padding. */
        if (flags & __PRINTF_FLAG_LEFTALIGNED) {
                if ((ret = print_padding(' ', padding_len, ps)) < 0)
                        return -1;

                counter += ret;
        }

        return counter;
}

/** Convert, format and print a double according to the %f specifier.
 *
 * @param g     Double to print.
 * @param precision Number of fractional digits to print. If 0 no
 *              decimal point will be printed unless the flag
 *              __PRINTF_FLAG_DECIMALPT is specified.
 * @param width Minimum number of characters to display. Pads
 *              with '0' or ' ' depending on the set flags;
 * @param flags Printf flags.
 * @param ps    Printing functions.
 *
 * @return The number of characters printed; negative on failure.
 */
static int print_double_fixed(double g, int precision, int width, uint32_t flags,
    printf_spec_t *ps)
{
        if (flags & __PRINTF_FLAG_LEFTALIGNED) {
                flags &= ~__PRINTF_FLAG_ZEROPADDED;
        }

        if (flags & __PRINTF_FLAG_DECIMALPT) {
                flags &= ~__PRINTF_FLAG_NOFRACZEROS;
        }

        ieee_double_t val = extract_ieee_double(g);

        if (val.is_special) {
                return print_special(val, width, flags, ps);
        }

        char buf[MAX_DOUBLE_STR_BUF_SIZE];
        const size_t buf_size = MAX_DOUBLE_STR_BUF_SIZE;
        double_str_t val_str;

        val_str.str = buf;
        val_str.neg = val.is_negative;

        if (0 <= precision) {
                /*
                 * Request one more digit so we can round the result. The last
                 * digit it returns may have an error of at most +/- 1.
                 */
                val_str.len = double_to_fixed_str(val, -1, precision + 1, buf, buf_size,
                    &val_str.dec_exp);

                /*
                 * Round using the last digit to produce precision fractional digits.
                 * If less than precision+1 fractional digits were output the last
                 * digit is definitely inaccurate so also round to get rid of it.
                 */
                fp_round_up(buf, &val_str.len, &val_str.dec_exp);

                /* Rounding could have introduced trailing zeros. */
                if (flags & __PRINTF_FLAG_NOFRACZEROS) {
                        fp_trim_trailing_zeros(buf, &val_str.len, &val_str.dec_exp);
                }
        } else {
                /* Let the implementation figure out the proper precision. */
                val_str.len = double_to_short_str(val, buf, buf_size, &val_str.dec_exp);

                /* Precision needed for the last significant digit. */
                precision = max(0, -val_str.dec_exp);
        }

        return print_double_str_fixed(&val_str, precision, width, flags, ps);
}

/** Prints the decimal exponent part of a %e specifier formatted number. */
static int print_exponent(int exp_val, uint32_t flags, printf_spec_t *ps)
{
        int counter = 0;
        int ret;

        char exp_ch = (flags & __PRINTF_FLAG_BIGCHARS) ? 'E' : 'e';

        if ((ret = ps->str_write(&exp_ch, 1, ps->data)) < 0)
                return -1;

        counter += ret;

        char exp_sign = (exp_val < 0) ? '-' : '+';

        if ((ret = ps->str_write(&exp_sign, 1, ps->data)) < 0)
                return -1;

        counter += ret;

        /* Print the exponent. */
        exp_val = abs(exp_val);

        char exp_str[4] = { 0 };

        exp_str[0] = '0' + exp_val / 100;
        exp_str[1] = '0' + (exp_val % 100) / 10;
        exp_str[2] = '0' + (exp_val % 10);

        int exp_len = (exp_str[0] == '0') ? 2 : 3;
        const char *exp_str_start = &exp_str[3] - exp_len;

        if ((ret = ps->str_write(exp_str_start, exp_len, ps->data)) < 0)
                return -1;

        counter += ret;

        return counter;
}

/** Format and print the double string repressentation according
 *  to the %e specifier.
 */
static int print_double_str_scient(double_str_t *val_str, int precision,
    int width, uint32_t flags, printf_spec_t *ps)
{
        int len = val_str->len;
        int dec_exp = val_str->dec_exp;
        char *buf  = val_str->str;

        assert(0 < len);

        char sign = get_sign_char(val_str->neg, flags);
        bool has_decimal_pt = (0 < precision) || (flags & __PRINTF_FLAG_DECIMALPT);
        int dec_pt_len = has_decimal_pt ? 1 : 0;

        /* Fractional part lengths. */
        int signif_frac_figs = len - 1;
        int trailing_frac_zeros = precision - signif_frac_figs;

        if (flags & __PRINTF_FLAG_NOFRACZEROS) {
                trailing_frac_zeros = 0;
        }

        int frac_len = signif_frac_figs + trailing_frac_zeros;

        int exp_val = dec_exp + len - 1;
        /* Account for exponent sign and 'e'; minimum 2 digits. */
        int exp_len = 2 + (abs(exp_val) >= 100 ? 3 : 2);

        /* Number of non-padding chars to print. */
        int num_len = (sign ? 1 : 0) + 1 + dec_pt_len + frac_len + exp_len;

        int padding_len = max(0, width - num_len);
        int ret = 0;
        int counter = 0;

        if (!(flags & (__PRINTF_FLAG_LEFTALIGNED | __PRINTF_FLAG_ZEROPADDED))) {
                if ((ret = print_padding(' ', padding_len, ps)) < 0)
                        return -1;

                counter += ret;
        }

        if (sign) {
                if ((ret = ps->str_write(&sign, 1, ps->data)) < 0)
                        return -1;

                counter += ret;
        }

        if (flags & __PRINTF_FLAG_ZEROPADDED) {
                if ((ret = print_padding('0', padding_len, ps)) < 0)
                        return -1;

                counter += ret;
        }

        /* Single leading integer. */
        if ((ret = ps->str_write(buf, 1, ps->data)) < 0)
                return -1;

        counter += ret;

        /* Print the decimal point and the fractional part. */
        if (has_decimal_pt) {
                char ch = '.';

                if ((ret = ps->str_write(&ch, 1, ps->data)) < 0)
                        return -1;

                counter += ret;

                /* Print significant digits of the fractional part of the number. */
                if (0 < signif_frac_figs) {
                        if ((ret = ps->str_write(buf + 1, signif_frac_figs, ps->data)) < 0)
                                return -1;

                        counter += ret;
                }

                /* Print trailing zeros of the fractional part of the number. */
                if ((ret = print_padding('0', trailing_frac_zeros, ps)) < 0)
                        return -1;

                counter += ret;
        }

        /* Print the exponent. */
        if ((ret = print_exponent(exp_val, flags, ps)) < 0)
                return -1;

        counter += ret;

        if (flags & __PRINTF_FLAG_LEFTALIGNED) {
                if ((ret = print_padding(' ', padding_len, ps)) < 0)
                        return -1;

                counter += ret;
        }

        return counter;
}

/** Convert, format and print a double according to the %e specifier.
 *
 * Note that if g is large, the output may be huge (3e100 prints
 * with at least 100 digits).
 *
 * %e style: [-]d.dddde+dd
 *  left-justified:  [-]d.dddde+dd[space_pad]
 *  right-justified: [space_pad][-][zero_pad]d.dddde+dd
 *
 * @param g     Double to print.
 * @param precision Number of fractional digits to print, ie
 *              precision + 1 significant digits to display. If 0 no
 *              decimal point will be printed unless the flag
 *              __PRINTF_FLAG_DECIMALPT is specified. If negative
 *              the shortest accurate number will be printed.
 * @param width Minimum number of characters to display. Pads
 *              with '0' or ' ' depending on the set flags;
 * @param flags Printf flags.
 * @param ps    Printing functions.
 *
 * @return The number of characters printed; negative on failure.
 */
static int print_double_scientific(double g, int precision, int width,
    uint32_t flags, printf_spec_t *ps)
{
        if (flags & __PRINTF_FLAG_LEFTALIGNED) {
                flags &= ~__PRINTF_FLAG_ZEROPADDED;
        }

        ieee_double_t val = extract_ieee_double(g);

        if (val.is_special) {
                return print_special(val, width, flags, ps);
        }

        char buf[MAX_DOUBLE_STR_BUF_SIZE];
        const size_t buf_size = MAX_DOUBLE_STR_BUF_SIZE;
        double_str_t val_str;

        val_str.str = buf;
        val_str.neg = val.is_negative;

        if (0 <= precision) {
                /*
                 * Request one more digit (in addition to the leading integer)
                 * so we can round the result. The last digit it returns may
                 * have an error of at most +/- 1.
                 */
                val_str.len = double_to_fixed_str(val, precision + 2, -1, buf, buf_size,
                    &val_str.dec_exp);

                /*
                 * Round the extra digit to produce precision+1 significant digits.
                 * If less than precision+2 significant digits were returned the last
                 * digit is definitely inaccurate so also round to get rid of it.
                 */
                fp_round_up(buf, &val_str.len, &val_str.dec_exp);

                /* Rounding could have introduced trailing zeros. */
                if (flags & __PRINTF_FLAG_NOFRACZEROS) {
                        fp_trim_trailing_zeros(buf, &val_str.len, &val_str.dec_exp);
                }
        } else {
                /* Let the implementation figure out the proper precision. */
                val_str.len = double_to_short_str(val, buf, buf_size, &val_str.dec_exp);

                /* Use all produced digits. */
                precision = val_str.len - 1;
        }

        return print_double_str_scient(&val_str, precision, width, flags, ps);
}

/** Convert, format and print a double according to the %g specifier.
 *
 * %g style chooses between %f and %e.
 *
 * @param g     Double to print.
 * @param precision Number of significant digits to display; excluding
 *              any leading zeros from this count. If negative
 *              the shortest accurate number will be printed.
 * @param width Minimum number of characters to display. Pads
 *              with '0' or ' ' depending on the set flags;
 * @param flags Printf flags.
 * @param ps    Printing functions.
 *
 * @return The number of characters printed; negative on failure.
 */
static int print_double_generic(double g, int precision, int width,
    uint32_t flags, printf_spec_t *ps)
{
        ieee_double_t val = extract_ieee_double(g);

        if (val.is_special) {
                return print_special(val, width, flags, ps);
        }

        char buf[MAX_DOUBLE_STR_BUF_SIZE];
        const size_t buf_size = MAX_DOUBLE_STR_BUF_SIZE;
        int dec_exp;
        int len;

        /* Honor the user requested number of significant digits. */
        if (0 <= precision) {
                /*
                 * Do a quick and dirty conversion of a single digit to determine
                 * the decimal exponent.
                 */
                len = double_to_fixed_str(val, 1, -1, buf, buf_size, &dec_exp);
                assert(0 < len);

                precision = max(1, precision);

                if (-4 <= dec_exp && dec_exp < precision) {
                        precision = precision - (dec_exp + 1);
                        return print_double_fixed(g, precision, width,
                            flags | __PRINTF_FLAG_NOFRACZEROS, ps);
                } else {
                        --precision;
                        return print_double_scientific(g, precision, width,
                            flags | __PRINTF_FLAG_NOFRACZEROS, ps);
                }
        } else {
                /* Convert to get the decimal exponent and digit count. */
                len = double_to_short_str(val, buf, buf_size, &dec_exp);
                assert(0 < len);

                if (flags & __PRINTF_FLAG_LEFTALIGNED) {
                        flags &= ~__PRINTF_FLAG_ZEROPADDED;
                }

                double_str_t val_str;
                val_str.str = buf;
                val_str.len = len;
                val_str.neg = val.is_negative;
                val_str.dec_exp = dec_exp;

                int first_digit_pos = len + dec_exp;
                int last_digit_pos = dec_exp;

                /* The whole number (15 digits max) fits between dec places 15 .. -6 */
                if (len <= 15 && -6 <= last_digit_pos && first_digit_pos <= 15) {
                        /* Precision needed for the last significant digit. */
                        precision = max(0, -val_str.dec_exp);
                        return print_double_str_fixed(&val_str, precision, width, flags, ps);
                } else {
                        /* Use all produced digits. */
                        precision = val_str.len - 1;
                        return print_double_str_scient(&val_str, precision, width, flags, ps);
                }
        }
}

/** Convert, format and print a double according to the specifier.
 *
 * Depending on the specifier it prints the double using the styles
 * %g, %f or %e by means of print_double_generic(), print_double_fixed(),
 * print_double_scientific().
 *
 * @param g     Double to print.
 * @param spec  Specifier of the style to print in; one of: 'g','G','f','F',
 *              'e','E'.
 * @param precision Number of fractional digits to display. If negative
 *              the shortest accurate number will be printed for style %g;
 *              negative precision defaults to 6 for styles %f, %e.
 * @param width Minimum number of characters to display. Pads
 *              with '0' or ' ' depending on the set flags;
 * @param flags Printf flags.
 * @param ps    Printing functions.
 *
 * @return The number of characters printed; negative on failure.
 */
static int print_double(double g, char spec, int precision, int width,
    uint32_t flags, printf_spec_t *ps)
{
        switch (spec) {
        case 'F':
                flags |= __PRINTF_FLAG_BIGCHARS;
                /* Fallthrough */
        case 'f':
                precision = (precision < 0) ? 6 : precision;
                return print_double_fixed(g, precision, width, flags, ps);

        case 'E':
                flags |= __PRINTF_FLAG_BIGCHARS;
                /* Fallthrough */
        case 'e':
                precision = (precision < 0) ? 6 : precision;
                return print_double_scientific(g, precision, width, flags, ps);

        case 'G':
                flags |= __PRINTF_FLAG_BIGCHARS;
                /* Fallthrough */
        case 'g':
                return print_double_generic(g, precision, width, flags, ps);

        default:
                assert(false);
                return -1;
        }
}

#endif

/** Print formatted string.
 *
 * Print string formatted according to the fmt parameter and variadic arguments.
 * Each formatting directive must have the following form:
 *
 *  \% [ FLAGS ] [ WIDTH ] [ .PRECISION ] [ TYPE ] CONVERSION
 *
 * FLAGS:@n
 *  - "#" Force to print prefix. For \%o conversion, the prefix is 0, for
 *        \%x and \%X prefixes are 0x and 0X and for conversion \%b the
 *        prefix is 0b.
 *
 *  - "-" Align to left.
 *
 *  - "+" Print positive sign just as negative.
 *
 *  - " " If the printed number is positive and "+" flag is not set,
 *        print space in place of sign.
 *
 *  - "0" Print 0 as padding instead of spaces. Zeroes are placed between
 *        sign and the rest of the number. This flag is ignored if "-"
 *        flag is specified.
 *
 * WIDTH:@n
 *  - Specify the minimal width of a printed argument. If it is bigger,
 *    width is ignored. If width is specified with a "*" character instead of
 *    number, width is taken from parameter list. And integer parameter is
 *    expected before parameter for processed conversion specification. If
 *    this value is negative its absolute value is taken and the "-" flag is
 *    set.
 *
 * PRECISION:@n
 *  - Value precision. For numbers it specifies minimum valid numbers.
 *    Smaller numbers are printed with leading zeroes. Bigger numbers are not
 *    affected. Strings with more than precision characters are cut off. Just
 *    as with width, an "*" can be used used instead of a number. An integer
 *    value is then expected in parameters. When both width and precision are
 *    specified using "*", the first parameter is used for width and the
 *    second one for precision.
 *
 * TYPE:@n
 *  - "hh" Signed or unsigned char.@n
 *  - "h"  Signed or unsigned short.@n
 *  - ""   Signed or unsigned int (default value).@n
 *  - "l"  Signed or unsigned long int.@n
 *         If conversion is "c", the character is wint_t (wide character).@n
 *         If conversion is "s", the string is char32_t * (wide string).@n
 *  - "ll" Signed or unsigned long long int.@n
 *  - "z"  Signed or unsigned ssize_t or site_t.@n
 *
 * CONVERSION:@n
 *  - % Print percentile character itself.
 *
 *  - c Print single character. The character is expected to be plain
 *      ASCII (e.g. only values 0 .. 127 are valid).@n
 *      If type is "l", then the character is expected to be wide character
 *      (e.g. values 0 .. 0x10ffff are valid).
 *
 *  - s Print zero terminated string. If a NULL value is passed as
 *      value, "(NULL)" is printed instead.@n
 *      If type is "l", then the string is expected to be wide string.
 *
 *  - P, p Print value of a pointer. Void * value is expected and it is
 *         printed in hexadecimal notation with prefix (as with
 *         \%#0.8X / \%#0.8x for 32-bit or \%#0.16lX / \%#0.16lx for 64-bit
 *         long pointers).
 *
 *  - b Print value as unsigned binary number. Prefix is not printed by
 *      default. (Nonstandard extension.)
 *
 *  - o Print value as unsigned octal number. Prefix is not printed by
 *      default.
 *
 *  - d, i Print signed decimal number. There is no difference between d
 *         and i conversion.
 *
 *  - u Print unsigned decimal number.
 *
 *  - X, x Print hexadecimal number with upper- or lower-case. Prefix is
 *         not printed by default.
 *
 * All other characters from fmt except the formatting directives are printed
 * verbatim.
 *
 * @param fmt Format NULL-terminated string.
 *
 * @return Number of characters printed, negative value on failure.
 *
 */
int printf_core(const char *fmt, printf_spec_t *ps, va_list ap)
{
        size_t i;        /* Index of the currently processed character from fmt */
        size_t nxt = 0;  /* Index of the next character from fmt */
        size_t j = 0;    /* Index to the first not printed nonformating character */

        size_t counter = 0;   /* Number of characters printed */
        int retval;           /* Return values from nested functions */

        while (true) {
                i = nxt;
                char32_t uc = str_decode(fmt, &nxt, STR_NO_LIMIT);

                if (uc == 0)
                        break;

                /* Control character */
                if (uc == '%') {
                        /* Print common characters if any processed */
                        if (i > j) {
                                if ((retval = printf_putnchars(&fmt[j], i - j, ps)) < 0) {
                                        /* Error */
                                        counter = -counter;
                                        goto out;
                                }
                                counter += retval;
                        }

                        j = i;

                        /* Parse modifiers */
                        uint32_t flags = 0;
                        bool end = false;

                        do {
                                i = nxt;
                                uc = str_decode(fmt, &nxt, STR_NO_LIMIT);
                                switch (uc) {
                                case '#':
                                        flags |= __PRINTF_FLAG_PREFIX;
                                        flags |= __PRINTF_FLAG_DECIMALPT;
                                        break;
                                case '-':
                                        flags |= __PRINTF_FLAG_LEFTALIGNED;
                                        break;
                                case '+':
                                        flags |= __PRINTF_FLAG_SHOWPLUS;
                                        break;
                                case ' ':
                                        flags |= __PRINTF_FLAG_SPACESIGN;
                                        break;
                                case '0':
                                        flags |= __PRINTF_FLAG_ZEROPADDED;
                                        break;
                                default:
                                        end = true;
                                }
                        } while (!end);

                        /* Width & '*' operator */
                        int width = 0;
                        if (isdigit(uc)) {
                                while (true) {
                                        width *= 10;
                                        width += uc - '0';

                                        i = nxt;
                                        uc = str_decode(fmt, &nxt, STR_NO_LIMIT);
                                        if (uc == 0)
                                                break;
                                        if (!isdigit(uc))
                                                break;
                                }
                        } else if (uc == '*') {
                                /* Get width value from argument list */
                                i = nxt;
                                uc = str_decode(fmt, &nxt, STR_NO_LIMIT);
                                width = (int) va_arg(ap, int);
                                if (width < 0) {
                                        /* Negative width sets '-' flag */
                                        width *= -1;
                                        flags |= __PRINTF_FLAG_LEFTALIGNED;
                                }
                        }

                        /* Precision and '*' operator */
                        int precision = -1;
                        if (uc == '.') {
                                i = nxt;
                                uc = str_decode(fmt, &nxt, STR_NO_LIMIT);
                                if (isdigit(uc)) {
                                        precision = 0;
                                        while (true) {
                                                precision *= 10;
                                                precision += uc - '0';

                                                i = nxt;
                                                uc = str_decode(fmt, &nxt, STR_NO_LIMIT);
                                                if (uc == 0)
                                                        break;
                                                if (!isdigit(uc))
                                                        break;
                                        }
                                } else if (uc == '*') {
                                        /* Get precision value from the argument list */
                                        i = nxt;
                                        uc = str_decode(fmt, &nxt, STR_NO_LIMIT);
                                        precision = (int) va_arg(ap, int);
                                        if (precision < 0) {
                                                /* Ignore negative precision - use default instead */
                                                precision = -1;
                                        }
                                }
                        }

                        qualifier_t qualifier;

                        switch (uc) {
                        case 't':
                                /* ptrdiff_t */
                                if (sizeof(ptrdiff_t) == sizeof(int32_t))
                                        qualifier = PrintfQualifierInt;
                                else
                                        qualifier = PrintfQualifierLongLong;
                                i = nxt;
                                uc = str_decode(fmt, &nxt, STR_NO_LIMIT);
                                break;
                        case 'h':
                                /* Char or short */
                                qualifier = PrintfQualifierShort;
                                i = nxt;
                                uc = str_decode(fmt, &nxt, STR_NO_LIMIT);
                                if (uc == 'h') {
                                        i = nxt;
                                        uc = str_decode(fmt, &nxt, STR_NO_LIMIT);
                                        qualifier = PrintfQualifierByte;
                                }
                                break;
                        case 'l':
                                /* Long or long long */
                                qualifier = PrintfQualifierLong;
                                i = nxt;
                                uc = str_decode(fmt, &nxt, STR_NO_LIMIT);
                                if (uc == 'l') {
                                        i = nxt;
                                        uc = str_decode(fmt, &nxt, STR_NO_LIMIT);
                                        qualifier = PrintfQualifierLongLong;
                                }
                                break;
                        case 'z':
                                qualifier = PrintfQualifierSize;
                                i = nxt;
                                uc = str_decode(fmt, &nxt, STR_NO_LIMIT);
                                break;
                        case 'j':
                                qualifier = PrintfQualifierMax;
                                i = nxt;
                                uc = str_decode(fmt, &nxt, STR_NO_LIMIT);
                                break;
                        default:
                                /* Default type */
                                qualifier = PrintfQualifierInt;
                        }

                        unsigned int base = 10;

                        switch (uc) {
                                /*
                                 * String and character conversions.
                                 */
                        case 's':
                                precision = max(0,  precision);

                                if (qualifier == PrintfQualifierLong)
                                        retval = print_wstr(va_arg(ap, char32_t *), width, precision, flags, ps);
                                else
                                        retval = print_str(va_arg(ap, char *), width, precision, flags, ps);

                                if (retval < 0) {
                                        counter = -counter;
                                        goto out;
                                }

                                counter += retval;
                                j = nxt;
                                continue;
                        case 'c':
                                if (qualifier == PrintfQualifierLong)
                                        retval = print_wchar(va_arg(ap, wint_t), width, flags, ps);
                                else
                                        retval = print_char(va_arg(ap, unsigned int), width, flags, ps);

                                if (retval < 0) {
                                        counter = -counter;
                                        goto out;
                                }

                                counter += retval;
                                j = nxt;
                                continue;

#ifdef HAS_FLOAT
                                /*
                                 * Floating point values
                                 */
                        case 'G':
                        case 'g':
                        case 'F':
                        case 'f':
                        case 'E':
                        case 'e':
                                retval = print_double(va_arg(ap, double), uc, precision,
                                    width, flags, ps);

                                if (retval < 0) {
                                        counter = -counter;
                                        goto out;
                                }

                                counter += retval;
                                j = nxt;
                                continue;
#endif

                                /*
                                 * Integer values
                                 */
                        case 'P':
                                /* Pointer */
                                flags |= __PRINTF_FLAG_BIGCHARS;
                                /* Fallthrough */
                        case 'p':
                                flags |= __PRINTF_FLAG_PREFIX;
                                flags |= __PRINTF_FLAG_ZEROPADDED;
                                base = 16;
                                qualifier = PrintfQualifierPointer;
                                break;
                        case 'b':
                                base = 2;
                                break;
                        case 'o':
                                base = 8;
                                break;
                        case 'd':
                        case 'i':
                                flags |= __PRINTF_FLAG_SIGNED;
                                /* Fallthrough */
                        case 'u':
                                break;
                        case 'X':
                                flags |= __PRINTF_FLAG_BIGCHARS;
                                /* Fallthrough */
                        case 'x':
                                base = 16;
                                break;

                        case '%':
                                /* Percentile itself */
                                j = i;
                                continue;

                                /*
                                 * Bad formatting.
                                 */
                        default:
                                /*
                                 * Unknown format. Now, j is the index of '%'
                                 * so we will print whole bad format sequence.
                                 */
                                continue;
                        }

                        /* Print integers */
                        size_t size;
                        uint64_t number;

                        switch (qualifier) {
                        case PrintfQualifierByte:
                                size = sizeof(unsigned char);
                                number = PRINTF_GET_INT_ARGUMENT(int, ap, flags);
                                break;
                        case PrintfQualifierShort:
                                size = sizeof(unsigned short);
                                number = PRINTF_GET_INT_ARGUMENT(int, ap, flags);
                                break;
                        case PrintfQualifierInt:
                                size = sizeof(unsigned int);
                                number = PRINTF_GET_INT_ARGUMENT(int, ap, flags);
                                break;
                        case PrintfQualifierLong:
                                size = sizeof(unsigned long);
                                number = PRINTF_GET_INT_ARGUMENT(long, ap, flags);
                                break;
                        case PrintfQualifierLongLong:
                                size = sizeof(unsigned long long);
                                number = PRINTF_GET_INT_ARGUMENT(long long, ap, flags);
                                break;
                        case PrintfQualifierPointer:
                                size = sizeof(void *);
                                precision = size << 1;
                                number = (uint64_t) (uintptr_t) va_arg(ap, void *);
                                break;
                        case PrintfQualifierSize:
                                size = sizeof(size_t);
                                number = (uint64_t) va_arg(ap, size_t);
                                break;
                        case PrintfQualifierMax:
                                size = sizeof(uintmax_t);
                                number = (uint64_t) va_arg(ap, uintmax_t);
                                break;
                        default:
                                /* Unknown qualifier */
                                counter = -counter;
                                goto out;
                        }

                        if ((retval = print_number(number, width, precision,
                            base, flags, ps)) < 0) {
                                counter = -counter;
                                goto out;
                        }

                        counter += retval;
                        j = nxt;
                }
        }

        if (i > j) {
                if ((retval = printf_putnchars(&fmt[j], i - j, ps)) < 0) {
                        /* Error */
                        counter = -counter;
                        goto out;
                }
                counter += retval;
        }

out:
        return ((int) counter);
}

/** @}
 */