135 lines
3.7 KiB
C
135 lines
3.7 KiB
C
/****************************************************************************
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* libs/libc/stdlib/lib_strtoul.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdlib.h>
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#include <errno.h>
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#include "libc.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: strtoul
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*
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* Description:
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* The strtoul() function converts the initial part of the string in
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* nptr to a long unsigned integer value according to the given base, which
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* must be between 2 and 36 inclusive, or be the special value 0.
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*
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* Returned Value:
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* - The converted value, if the base and number are valid
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* - 0 if an error occurs, and set errno to:
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* * EINVAL if base < 2 or base > 36
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* - ULONG_MAX if an overflow occurs, and set errno to:
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* * ERANGE if the number cannot be represented using unsigned long
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*
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****************************************************************************/
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unsigned long strtoul(FAR const char *nptr, FAR char **endptr, int base)
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{
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FAR const char *origin = nptr;
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unsigned long accum = 0;
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unsigned long limit;
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int value = -1;
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int last_digit;
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char sign = 0;
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if (nptr)
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{
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/* Skip leading spaces */
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lib_skipspace(&nptr);
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/* Check for leading + or - already done for strtol */
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if (*nptr == '-' || *nptr == '+')
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{
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sign = *nptr;
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nptr++;
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}
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/* Check for unspecified or incorrect base */
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base = lib_checkbase(base, &nptr);
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if (base < 0)
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{
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set_errno(EINVAL);
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}
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else
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{
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limit = ULONG_MAX / base;
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last_digit = ULONG_MAX % base;
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/* Accumulate each "digit" */
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while (lib_isbasedigit(*nptr, base, &value))
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{
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/* Check for overflow */
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if (accum > limit || (accum == limit && value > last_digit))
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{
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set_errno(ERANGE);
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accum = ULONG_MAX;
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break;
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}
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accum = accum * base + value;
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nptr++;
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}
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while (lib_isbasedigit(*nptr, base, &value))
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{
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nptr++;
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}
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if (sign == '-')
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{
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accum = (~accum) + 1;
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}
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}
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}
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/* Return the final pointer to the unused value */
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if (endptr)
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{
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if (sign)
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{
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if (*(nptr - 1) == sign)
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{
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nptr--;
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}
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}
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*endptr = (FAR char *)(value == -1 ? origin : nptr);
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}
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return accum;
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}
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