/* fpconv - Floating point conversion routines * * Copyright (c) 2011-2012  Mark Pulford <mark@kyne.com.au> * * Permission is hereby granted, free of charge, to any person obtaining * a copy of this software and associated documentation files (the * "Software"), to deal in the Software without restriction, including * without limitation the rights to use, copy, modify, merge, publish, * distribute, sublicense, and/or sell copies of the Software, and to * permit persons to whom the Software is furnished to do so, subject to * the following conditions: * * The above copyright notice and this permission notice shall be * included in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ /* JSON uses a '.' decimal separator. strtod() / sprintf() under C libraries * with locale support will break when the decimal separator is a comma. * * fpconv_* will around these issues with a translation buffer if required. */ #include <stdio.h>#include <stdlib.h>#include <assert.h>#include <string.h> #include "fpconv.h" /* Lua CJSON assumes the locale is the same for all threads within a * process and doesn't change after initialisation. * * This avoids the need for per thread storage or expensive checks * for call. */static char locale_decimal_point = '.'; /* In theory multibyte decimal_points are possible, but * Lua CJSON only supports UTF-8 and known locales only have * single byte decimal points ([.,]). * * localconv() may not be thread safe (=>crash), and nl_langinfo() is * not supported on some platforms. Use sprintf() instead - if the * locale does change, at least Lua CJSON won't crash. */static void fpconv_update_locale(){    char buf[8];     snprintf(buf, sizeof(buf), "%g", 0.5);     /* Failing this test might imply the platform has a buggy dtoa     * implementation or wide characters */    if (buf[0] != '0' || buf[2] != '5' || buf[3] != 0) {        fprintf(stderr, "Error: wide characters found or printf() bug.");        abort();    }     locale_decimal_point = buf[1];} /* Check for a valid number character: [-+0-9a-yA-Y.] * Eg: -0.6e+5, infinity, 0xF0.F0pF0 * * Used to find the probable end of a number. It doesn't matter if * invalid characters are counted - strtod() will find the valid * number if it exists.  The risk is that slightly more memory might * be allocated before a parse error occurs. */static inline int valid_number_character(char ch){    char lower_ch;     if ('0' <= ch && ch <= '9')        return 1;    if (ch == '-' || ch == '+' || ch == '.')        return 1;     /* Hex digits, exponent (e), base (p), "infinity",.. */    lower_ch = ch | 0x20;    if ('a' <= lower_ch && lower_ch <= 'y')        return 1;     return 0;} /* Calculate the size of the buffer required for a strtod locale * conversion. */static int strtod_buffer_size(const char *s){    const char *p = s;     while (valid_number_character(*p))        p++;     return p - s;} /* Similar to strtod(), but must be passed the current locale's decimal point * character. Guaranteed to be called at the start of any valid number in a string */double fpconv_strtod(const char *nptr, char **endptr){    char localbuf[FPCONV_G_FMT_BUFSIZE];    char *buf, *endbuf, *dp;    int buflen;    double value;     /* System strtod() is fine when decimal point is '.' */    if (locale_decimal_point == '.')        return strtod(nptr, endptr);     buflen = strtod_buffer_size(nptr);    if (!buflen) {        /* No valid characters found, standard strtod() return */        *endptr = (char *)nptr;        return 0;    }     /* Duplicate number into buffer */    if (buflen >= FPCONV_G_FMT_BUFSIZE) {        /* Handle unusually large numbers */        buf = malloc(buflen + 1);        if (!buf) {            fprintf(stderr, "Out of memory");            abort();        }    } else {        /* This is the common case.. */        buf = localbuf;    }    memcpy(buf, nptr, buflen);    buf[buflen] = 0;     /* Update decimal point character if found */    dp = strchr(buf, '.');    if (dp)        *dp = locale_decimal_point;     value = strtod(buf, &endbuf);    *endptr = (char *)&nptr[endbuf - buf];    if (buflen >= FPCONV_G_FMT_BUFSIZE)        free(buf);     return value;} /* "fmt" must point to a buffer of at least 6 characters */static void set_number_format(char *fmt, int precision){    int d1, d2, i;     assert(1 <= precision && precision <= 14);     /* Create printf format (%.14g) from precision */    d1 = precision / 10;    d2 = precision % 10;    fmt[0] = '%';    fmt[1] = '.';    i = 2;    if (d1) {        fmt[i++] = '0' + d1;    }    fmt[i++] = '0' + d2;    fmt[i++] = 'g';    fmt[i] = 0;} /* Assumes there is always at least 32 characters available in the target buffer */int fpconv_g_fmt(char *str, double num, int precision){    char buf[FPCONV_G_FMT_BUFSIZE];    char fmt[6];    int len;    char *b;     set_number_format(fmt, precision);     /* Pass through when decimal point character is dot. */    if (locale_decimal_point == '.')        return snprintf(str, FPCONV_G_FMT_BUFSIZE, fmt, num);     /* snprintf() to a buffer then translate for other decimal point characters */    len = snprintf(buf, FPCONV_G_FMT_BUFSIZE, fmt, num);     /* Copy into target location. Translate decimal point if required */    b = buf;    do {        *str++ = (*b == locale_decimal_point ? '.' : *b);    } while(*b++);     return len;} void fpconv_init(){    fpconv_update_locale();} /* vi:ai et sw=4 ts=4: */