diff options
Diffstat (limited to 'gnu/lib/libg++/iostream/outfloat.C')
| -rw-r--r-- | gnu/lib/libg++/iostream/outfloat.C | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/gnu/lib/libg++/iostream/outfloat.C b/gnu/lib/libg++/iostream/outfloat.C new file mode 100644 index 00000000000..c677844b839 --- /dev/null +++ b/gnu/lib/libg++/iostream/outfloat.C @@ -0,0 +1,183 @@ +// This is part of the iostream library, providing input/output for C++. +// Copyright (C) 1992 Per Bothner. +// +// This library is free software; you can redistribute it and/or +// modify it under the terms of the GNU Library General Public +// License as published by the Free Software Foundation; either +// version 2 of the License, or (at your option) any later version. +// +// This library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +// Library General Public License for more details. +// +// You should have received a copy of the GNU Library General Public +// License along with this library; if not, write to the Free +// Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + +#include "ioprivate.h" + +// Format floating-point number and print them. +// Return number of chars printed, or EOF on error. + +// sign_mode == '+' : print "-" or "+" +// sign_mode == ' ' : print "-" or " " +// sign_mode == '\0' : print "-' or "" + +int __outfloat(double value, streambuf *sb, char type, + int width, int precision, ios::fmtflags flags, + char sign_mode, char fill) +{ + int count = 0; +#define PUT(x) do {if (sb->sputc(x) < 0) goto error; count++;} while (0) +#define PUTN(p, n) \ + do {int _n=n; count+=_n; if (sb->sputn(p,_n) != _n) goto error;} while(0) +#define PADN(fill, n) \ + do {int _n = n; count+=_n; if (sb->padn(fill, _n) < 0) goto error;} while (0) + ios::fmtflags pad_kind = flags & (ios::left|ios::right|ios::internal); + int skip_zeroes = 0; + int show_dot = (flags & ios::showpoint) != 0; + int decpt; + int sign; + int mode; +#define EBUF_SIZE 12 +#define EBUF_END &ebuf[EBUF_SIZE] + char ebuf[EBUF_SIZE]; + char *end; + int exp = 0; + switch (type) { + case 'f': + mode = 3; + break; + case 'e': + case 'E': + exp = type; + mode = 2; + if (precision != 999) + precision++; // Add one to include digit before decimal point. + break; + case 'g': + case 'G': + exp = type == 'g' ? 'e' : 'E'; + if (precision == 0) precision = 1; + if (!(flags & ios::showpoint)) + skip_zeroes = 1; + type = 'g'; + mode = 2; + break; + } + /* Do the actual convension */ + if (precision == 999 && mode != 3) + mode = 0; + char *p = dtoa(value, mode, precision, &decpt, &sign, &end); + register int i; + int useful_digits = end-p; + char *exponent_start = EBUF_END; + if (mode == 0) + precision = useful_digits; + // Check if we need to emit an exponent. + if (mode != 3 && decpt != 9999) { + i = decpt - 1; + if ((type != 'g' && type != 'F') || i < -4 || i >= precision) { + // Print the exponent into ebuf. + // We write ebuf in reverse order (right-to-left). + char sign; + if (i >= 0) + sign = '+'; + else + sign = '-', i = -i; + /* Note: ANSI requires at least 2 exponent digits. */ + do { + *--exponent_start = (i % 10) + '0'; + i /= 10; + } while (i >= 10); + *--exponent_start = i + '0'; + *--exponent_start = sign; + *--exponent_start = exp; + } + } + int exponent_size = EBUF_END - exponent_start; + if (mode == 1) + precision = 1; + /* If we print an exponent, always show just one digit before point. */ + if (exponent_size) + decpt = 1; + if (decpt == 9999) { // Infinity or NaN + decpt = useful_digits; + precision = 0; + show_dot = 0; + } + + // dtoa truncates trailing zeroes. Set the variable trailing_zeroes to + // the number of 0's we have to add (after the decimal point). + int trailing_zeroes = 0; + if (skip_zeroes) + trailing_zeroes = 0; + else if (type == 'f') + trailing_zeroes = useful_digits <= decpt ? precision + : precision-(useful_digits-decpt); + else if (exponent_size) // 'e' 'E' or 'g' format using exponential notation. + trailing_zeroes = precision - useful_digits; + else // 'g' format not using exponential notation. + trailing_zeroes = useful_digits <= decpt ? precision - decpt + : precision-useful_digits; + if (trailing_zeroes < 0) trailing_zeroes = 0; + + if (trailing_zeroes != 0 || useful_digits > decpt) + show_dot = 1; + int print_sign; + if (sign_mode == 0) + print_sign = sign ? '-' : 0; + else if (sign_mode == '+') + print_sign = sign ? '-' : '+'; + else /* if (sign_mode == ' ') */ + print_sign = sign ? '-' : ' '; + + // Calculate the width (before padding). + int unpadded_width = + (print_sign != 0) + trailing_zeroes + exponent_size + show_dot + + useful_digits + + (decpt > useful_digits ? decpt - useful_digits + : decpt > 0 ? 0 : 1 - decpt); + + int padding = width > unpadded_width ? width - unpadded_width : 0; + if (padding > 0 + && pad_kind != (ios::fmtflags)ios::left + && pad_kind != (ios::fmtflags)ios::internal) // Default (right) adjust. + PADN(fill, padding); + if (print_sign) + PUT(print_sign); + if (pad_kind == (ios::fmtflags)ios::internal && padding > 0) + PADN(fill, padding); + if (decpt > 0) { + if (useful_digits >= decpt) + PUTN(p, decpt); + else { + PUTN(p, useful_digits); + PADN('0', decpt-useful_digits); + } + if (show_dot) { + PUT('.'); + // Print digits after the decimal point. + if (useful_digits > decpt) + PUTN(p + decpt, useful_digits-decpt); + } + } + else { + PUT('0'); + if (show_dot) { + PUT('.'); + PADN('0', -decpt); + // Print digits after the decimal point. + PUTN(p, useful_digits); + } + } + PADN('0', trailing_zeroes); + if (exponent_size) + PUTN(exponent_start, exponent_size); + if (pad_kind == (ios::fmtflags)ios::left && padding > 0) // Left adjustment + PADN(fill, padding); + return count; + error: + return EOF; +} |