Changeset 34b9299 in mainline

Timestamp:

2012-10-31T19:47:53Z (11 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

82d062d8

Parents:

f0da6855

git-author:

Adam Hraska <adam.hraska@…> (2012-10-31 19:47:53)

git-committer:

Jakub Jermar <jakub@…> (2012-10-31 19:47:53)

Message:

printf() full floating point support.
(Thanks to Adam Hraska.)

Location:

uspace

Files:

• app/tester/Makefile (modified) (1 diff)
• app/tester/print/print5.def (modified) (1 diff)
• app/tester/print/print6.c (added)
• app/tester/print/print6.def (added)
• app/tester/tester.c (modified) (1 diff)
• app/tester/tester.h (modified) (1 diff)
• lib/c/Makefile (modified) (1 diff)
• lib/c/generic/double_to_str.c (added)
• lib/c/generic/ieee_double.c (added)
• lib/c/generic/io/printf_core.c (modified) (12 diffs)
• lib/c/generic/power_of_ten.c (added)
• lib/c/generic/private/power_of_ten.h (added)
• lib/c/include/double_to_str.h (added)
• lib/c/include/ieee_double.h (added)
• lib/c/include/macros.h (modified) (1 diff)

uspace/app/tester/Makefile

@@ -42 +42 @@
         print/print4.c \
         print/print5.c \
+        print/print6.c \
         console/console1.c \
         stdio/stdio1.c \

uspace/app/tester/print/print5.def

@@ -1 +1 @@
 {
-        "print1",
-        "String printf test",
-        &test_print1,
+        "print5",
+        "Char printf test",
+        &test_print5,
         true
 },

uspace/app/tester/tester.c

@@ -53 +53 @@
 #include "print/print4.def"
 #include "print/print5.def"
+#include "print/print6.def"
 #include "console/console1.def"
 #include "stdio/stdio1.def"

uspace/app/tester/tester.h

@@ -85 +85 @@
 extern const char *test_print4(void);
 extern const char *test_print5(void);
+extern const char *test_print6(void);
 extern const char *test_console1(void);
 extern const char *test_stdio1(void);

uspace/lib/c/Makefile

@@ -116 +116 @@
         generic/iplink.c \
         generic/iplink_srv.c \
+        generic/ieee_double.c \
+        generic/power_of_ten.c \
+        generic/double_to_str.c \
         generic/malloc.c \
         generic/sysinfo.c \

uspace/lib/c/generic/io/printf_core.c

@@ -42 +42 @@
 #include <ctype.h>
 #include <str.h>
+#include <double_to_str.h>
+#include <ieee_double.h>
+#include <assert.h>
+#include <macros.h>
+
 
 /** 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
@@ -66 +74 @@
 /** number has - sign */
 #define __PRINTF_FLAG_NEGATIVE     0x00000100
+
+/** don't print trailing zeros in the fractional part */
+#define __PRINTF_FLAG_NOFRACZEROS  0x00000200
+
 
 /**
@@ -110 +122 @@
 static const char invalch = U_SPECIAL;
 
+
+
+/** 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;
+}
+
+
 /** Print one or more characters without adding newline.
  *
@@ -281 +336 @@
                 return printf_putstr(nullstr, ps);
         
-        /* Print leading spaces. */
         size_t strw = str_length(str);
+
+        /* Precision unspecified - print everything. */
         if ((precision == 0) || (precision > strw))
                 precision = strw;
@@ -329 +385 @@
                 return printf_putstr(nullstr, ps);
         
-        /* Print leading spaces. */
         size_t strw = wstr_length(str);
+
+        /* Precision not specified - print everything. */
         if ((precision == 0) || (precision > strw))
                 precision = strw;
@@ -377 +434 @@
     uint32_t flags, printf_spec_t *ps)
 {
+        /* Precision not specified. */
+        if (precision < 0) {
+                precision = 0;
+        }
+        
         const char *digits;
         if (flags & __PRINTF_FLAG_BIGCHARS)
@@ -525 +587 @@
         
         return ((int) counter);
+}
+
+/** 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;
+                /* Fall through.*/
+        case 'f':
+                precision = (precision < 0) ? 6 : precision;
+                return print_double_fixed(g, precision, width, flags, ps);
+
+        case 'E':
+                flags |= __PRINTF_FLAG_BIGCHARS;
+                /* Fall through.*/
+        case 'e':
+                precision = (precision < 0) ? 6 : precision;
+                return print_double_scientific(g, precision, width, flags, ps);
+
+        case 'G':
+                flags |= __PRINTF_FLAG_BIGCHARS;
+                /* Fall through.*/
+        case 'g':
+                return print_double_generic(g, precision, width, flags, ps);
+
+        default:
+                assert(false);
+                return -1;
+        }
 }
 
@@ -656 +1370 @@
                                 case '#':
                                         flags |= __PRINTF_FLAG_PREFIX;
+                                        flags |= __PRINTF_FLAG_DECIMALPT;
                                         break;
                                 case '-':
@@ -701 +1416 @@
                         
                         /* Precision and '*' operator */
-                        int precision = 0;
+                        int precision = -1;
                         if (uc == '.') {
                                 i = nxt;
                                 uc = str_decode(fmt, &nxt, STR_NO_LIMIT);
                                 if (isdigit(uc)) {
+                                        precision = 0;
                                         while (true) {
                                                 precision *= 10;
@@ -723 +1439 @@
                                         precision = (int) va_arg(ap, int);
                                         if (precision < 0) {
-                                                /* Ignore negative precision */
-                                                precision = 0;
+                                                /* Ignore negative precision - use default instead */
+                                                precision = -1;
                                         }
                                 }
@@ -774 +1490 @@
                          */
                         case 's':
+                                precision = max(0,  precision);
+                                
                                 if (qualifier == PrintfQualifierLong)
                                         retval = print_wstr(va_arg(ap, wchar_t *), width, precision, flags, ps);
@@ -797 +1515 @@
                                         goto out;
                                 };
+                                
+                                counter += retval;
+                                j = nxt;
+                                goto next_char;
+                                
+                        /*
+                         * 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;

uspace/lib/c/include/macros.h

@@ -38 +38 @@
 #define min(a, b)  ((a) < (b) ? (a) : (b))
 #define max(a, b)  ((a) > (b) ? (a) : (b))
+#define abs(a)     ((a) >= 0 ? (a) : (-a))
+
 
 #define KiB2SIZE(kb)  ((kb) << 10)