210 lines
6.8 KiB
C++
210 lines
6.8 KiB
C++
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/***
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*wcstoi64.c - Contains C runtimes wcstoi64 and wcstoui64
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*
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* Copyright (c) 1989-1996, Microsoft Corporation. All rights reserved.
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*
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*Purpose:
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* wcstol - convert wchar_t string to long signed integer
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* wcstoul - convert wchar_t string to long unsigned integer
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*
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*Revision History:
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*
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*******************************************************************************/
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#include <pch.cxx>
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#pragma hdrstop
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#include <errno.h>
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/***
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*wcstol, wcstoul(nptr,endptr,ibase) - Convert ascii string to long un/signed
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* int.
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*
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*Purpose:
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* Convert an ascii string to a long 64-bit value. The base
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* used for the caculations is supplied by the caller. The base
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* must be in the range 0, 2-36. If a base of 0 is supplied, the
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* ascii string must be examined to determine the base of the
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* number:
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* (a) First char = '0', second char = 'x' or 'X',
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* use base 16.
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* (b) First char = '0', use base 8
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* (c) First char in range '1' - '9', use base 10.
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*
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* If the 'endptr' value is non-NULL, then wcstol/wcstoul places
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* a pointer to the terminating character in this value.
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* See ANSI standard for details
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*
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*Entry:
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* nptr == NEAR/FAR pointer to the start of string.
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* endptr == NEAR/FAR pointer to the end of the string.
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* ibase == integer base to use for the calculations.
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*
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* string format: [whitespace] [sign] [0] [x] [digits/letters]
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*
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*Exit:
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* Good return:
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* result
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*
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* Overflow return:
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* wcstol -- _I64_MAX or _I64_MIN
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* wcstoul -- _UI64_MAX
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* wcstol/wcstoul -- errno == ERANGE
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*
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* No digits or bad base return:
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* 0
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* endptr = nptr*
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*
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*Exceptions:
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* None.
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*******************************************************************************/
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/* flag values */
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#define FL_UNSIGNED 1 /* wcstoul called */
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#define FL_NEG 2 /* negative sign found */
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#define FL_OVERFLOW 4 /* overflow occured */
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#define FL_READDIGIT 8 /* we've read at least one correct digit */
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static
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unsigned _int64
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wcstoxi64 (
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const wchar_t *nptr,
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wchar_t **endptr,
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int ibase,
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int flags
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)
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{
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const wchar_t *p;
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wchar_t c;
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unsigned _int64 number;
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unsigned digval;
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unsigned _int64 maxval;
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p = nptr; /* p is our scanning pointer */
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number = 0; /* start with zero */
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c = *p++; /* read char */
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while (iswspace(c))
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c = *p++; /* skip whitespace */
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if (c == '-') {
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flags |= FL_NEG; /* remember minus sign */
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c = *p++;
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}
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else if (c == '+')
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c = *p++; /* skip sign */
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if (ibase < 0 || ibase == 1 || ibase > 36) {
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/* bad base! */
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if (endptr)
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/* store beginning of string in endptr */
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*endptr = (wchar_t *) nptr;
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return 0L; /* return 0 */
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}
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else if (ibase == 0) {
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/* determine base free-lance, based on first two chars of
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string */
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if (c != L'0')
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ibase = 10;
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else if (*p == L'x' || *p == L'X')
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ibase = 16;
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else
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ibase = 8;
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}
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if (ibase == 16) {
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/* we might have 0x in front of number; remove if there */
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if (c == L'0' && (*p == L'x' || *p == L'X')) {
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++p;
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c = *p++; /* advance past prefix */
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}
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}
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/* if our number exceeds this, we will overflow on multiply */
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maxval = _UI64_MAX / ibase;
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for (;;) { /* exit in middle of loop */
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/* convert c to value */
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if (iswdigit(c))
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digval = c - L'0';
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else if (iswalpha(c))
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digval = towupper(c) - L'A' + 10;
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else
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break;
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if (digval >= (unsigned)ibase)
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break; /* exit loop if bad digit found */
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/* record the fact we have read one digit */
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flags |= FL_READDIGIT;
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/* we now need to compute number = number * base + digval,
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but we need to know if overflow occured. This requires
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a tricky pre-check. */
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if (number < maxval || (number == maxval &&
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(unsigned _int64)digval <= _UI64_MAX % ibase)) {
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/* we won't overflow, go ahead and multiply */
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number = number * ibase + digval;
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}
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else {
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/* we would have overflowed -- set the overflow flag */
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flags |= FL_OVERFLOW;
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}
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c = *p++; /* read next digit */
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}
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--p; /* point to place that stopped scan */
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if (!(flags & FL_READDIGIT)) {
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/* no number there; return 0 and point to beginning of
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string */
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if (endptr)
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/* store beginning of string in endptr later on */
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p = nptr;
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number = 0L; /* return 0 */
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}
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else if ( (flags & FL_OVERFLOW) ||
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( !(flags & FL_UNSIGNED) &&
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( ( (flags & FL_NEG) && (number > -_I64_MIN) ) ||
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( !(flags & FL_NEG) && (number > _I64_MAX) ) ) ) )
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{
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/* overflow or signed overflow occurred */
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errno = ERANGE;
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if ( flags & FL_UNSIGNED )
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number = _UI64_MAX;
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else if ( flags & FL_NEG )
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number = (unsigned _int64)(-_I64_MIN);
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else
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number = _I64_MAX;
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}
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if (endptr != NULL)
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/* store pointer to char that stopped the scan */
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*endptr = (wchar_t *) p;
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if (flags & FL_NEG)
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/* negate result if there was a neg sign */
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number = (unsigned _int64)(-(_int64)number);
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return number; /* done. */
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}
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_int64 __cdecl _wcstoi64 (
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const wchar_t *nptr,
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wchar_t **endptr,
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int ibase
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)
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{
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return (_int64) wcstoxi64(nptr, endptr, ibase, 0);
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}
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unsigned _int64 __cdecl _wcstoui64 (
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const wchar_t *nptr,
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wchar_t **endptr,
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int ibase
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)
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{
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return wcstoxi64(nptr, endptr, ibase, FL_UNSIGNED);
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}
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