/* Convert a floating-point number to string. Copyright (C) 2016 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. The GNU C 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 Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, see . */ /* Generic implementation for strfrom functions. The implementation is generic for several floating-point types (e.g.: float, double), so that each function, such as strfromf and strfroml, share the same code, thus avoiding code duplication. */ #include #include "../libio/libioP.h" #include "../libio/strfile.h" #include #include #include #define UCHAR_T char #define L_(Str) Str #define ISDIGIT(Ch) isdigit (Ch) #include "stdio-common/printf-parse.h" int STRFROM (char *dest, size_t size, const char *format, FLOAT f) { _IO_strnfile sfile; #ifdef _IO_MTSAFE_IO sfile.f._sbf._f._lock = NULL; #endif int done; /* Single-precision values need to be stored in a double type, because __printf_fp_l and __printf_fphex do not accept the float type. */ union { double flt; FLOAT value; } fpnum; const void *fpptr; fpptr = &fpnum; /* Variables to control the output format. */ int precision = -1; /* printf_fp and printf_fphex treat this internally. */ int specifier; struct printf_info info; /* Single-precision values need to be converted into double-precision, because __printf_fp and __printf_fphex only accept double and long double as the floating-point argument. */ if (__builtin_types_compatible_p (FLOAT, float)) fpnum.flt = f; else fpnum.value = f; /* Check if the first character in the format string is indeed the '%' character. Otherwise, abort. */ if (*format == '%') format++; else abort (); /* The optional precision specification always starts with a '.'. If such character is present, read the precision. */ if (*format == '.') { format++; /* Parse the precision. */ if (ISDIGIT (*format)) precision = read_int (&format); /* If only the period is specified, the precision is taken as zero, as described in ISO/IEC 9899:2011, section 7.21.6.1, 4th paragraph, 3rd item. */ else precision = 0; } /* Now there is only the conversion specifier to be read. */ switch (*format) { case 'a': case 'A': case 'e': case 'E': case 'f': case 'F': case 'g': case 'G': specifier = *format; break; default: abort (); } /* The following code to prepare the virtual file has been adapted from the function _IO_vsnprintf from libio. */ if (size == 0) { /* When size is zero, nothing is written and dest may be a null pointer. This is specified for snprintf in ISO/IEC 9899:2011, Section 7.21.6.5, in the second paragraph. Thus, if size is zero, prepare to use the overflow buffer right from the start. */ dest = sfile.overflow_buf; size = sizeof (sfile.overflow_buf); } /* Prepare the virtual string file. */ _IO_no_init (&sfile.f._sbf._f, _IO_USER_LOCK, -1, NULL, NULL); _IO_JUMPS (&sfile.f._sbf) = &_IO_strn_jumps; _IO_str_init_static_internal (&sfile.f, dest, size - 1, dest); /* Prepare the format specification for printf_fp. */ memset (&info, '\0', sizeof (info)); /* The functions strfromd and strfromf pass a floating-point number with double precision to printf_fp, whereas strfroml passes a floating-point number with long double precision. The following line informs printf_fp which type of floating-point number is being passed. */ info.is_long_double = __builtin_types_compatible_p (FLOAT, long double); /* Set info according to the format string. */ info.prec = precision; info.spec = specifier; if (info.spec != 'a' && info.spec != 'A') done = __printf_fp_l (&sfile.f._sbf._f, _NL_CURRENT_LOCALE, &info, &fpptr); else done = __printf_fphex (&sfile.f._sbf._f, &info, &fpptr); /* Terminate the string. */ if (sfile.f._sbf._f._IO_buf_base != sfile.overflow_buf) *sfile.f._sbf._f._IO_write_ptr = '\0'; return done; }