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112 lines
2.3 KiB
112 lines
2.3 KiB
2 months ago
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/*
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* UCW Library -- Conversions of Strings to Numbers
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*
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* (c) 2010 Daniel Fiala <danfiala@ucw.cz>
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*
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* This software may be freely distributed and used according to the terms
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* of the GNU Lesser General Public License.
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*/
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/*
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* This is not a normal header file, it is a generator of a function for
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* converting strings to integers of a certain type. This file should be used
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* by ucw/stronum.c only.
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*/
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#define STN_DECLARE(type, suffix) STN_DECLARE_CONVERTOR(type, suffix)
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#define S_HELPER2(name, suffix) name##suffix
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#define S_HELPER1(name, suffix) S_HELPER2(name, suffix)
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#define S(name) S_HELPER1(name, STN_SUFFIX)
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#define STN_MAX ((STN_TYPE)(-1))
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static const STN_TYPE S(tops)[STN_DBASES_MASK+1] = { [2] = STN_MAX/2, [8] = STN_MAX/8, [10] = STN_MAX/10, [16] = STN_MAX/16 };
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static const char *S(parse_string)(const char **pp, const uint flags, const uint sign, const uint base, STN_TYPE *num)
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{
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const STN_TYPE max = STN_MAX;
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const STN_TYPE top = S(tops)[base];
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if (!top)
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return "Unknown base";
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const STN_TYPE sign_max = ((flags & STN_SIGNED) || sign) ? max/2 + sign : max;
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STN_TYPE val = 0;
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uint digits = 0;
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int overflow = 0;
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for (;; (*pp)++)
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{
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const uint c = (byte)**pp;
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if (c == '_')
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{
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if (flags & STN_UNDERSCORE)
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continue;
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else
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break;
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}
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const uint d = get_digit(c);
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if (d >= base)
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break;
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digits++;
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if (overflow)
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continue;
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STN_TYPE v = val;
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if ( (overflow = (v > top || (v *= base) > sign_max - d)) )
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continue;
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val = v + d;
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}
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if (!overflow)
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{
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if (!digits)
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return "Number contains no digits";
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if (sign)
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val = -val;
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}
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else
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{
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if (flags & STN_TRUNC)
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val = sign_max;
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else
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return "Numeric overflow";
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}
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if ((flags & STN_WHOLE) && **pp)
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return "Invalid character";
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if (num)
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*num = val;
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return NULL;
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}
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STN_DECLARE(STN_TYPE, STN_SUFFIX)
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{
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const char *err = NULL;
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uint sign, base;
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err = str_to_num_init(&str, flags, &sign, &base);
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if (!err)
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err = S(parse_string)(&str, flags, sign, base, num);
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if (next)
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*next = str;
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return err;
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}
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#undef STN_MAX
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#undef S
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#undef S_HELPER1
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#undef S_HELPER2
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#undef STN_TYPE
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#undef STN_SUFFIX
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#undef STN_DECLARE
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