115 lines
3.2 KiB
C
115 lines
3.2 KiB
C
/****************************************************************************
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* libs/libc/stdlib/lib_checkbase.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 <string.h>
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#include <ctype.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: lib_checkbase
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*
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* Description:
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* This is part of the strol() family implementation. This function checks
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* the initial part of a string to see if it can determine the numeric
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* base that is represented.
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*
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* Assumptions:
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* *ptr points to the first, non-whitespace character in the string.
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*
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* Returned Value:
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* - if base is valid, the actual base to use, and pptr is updated to point
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* at the first digit.
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* - if base is invalid (<2 or >36), return -1.
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*
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****************************************************************************/
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int lib_checkbase(int base, FAR const char **pptr)
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{
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FAR const char *ptr = *pptr;
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/* Check for unspecified base */
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if (!base)
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{
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/* Assume base 10 */
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base = 10;
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/* Check for leading '0' - that would signify octal
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* or hex (or binary)
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*/
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if (*ptr == '0')
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{
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/* Assume octal */
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if (lib_isbasedigit(ptr[1], 8, NULL))
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{
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base = 8;
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ptr++;
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}
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/* Check for hexadecimal */
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else if ((ptr[1] == 'X' || ptr[1] == 'x') &&
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lib_isbasedigit(ptr[2], 16, NULL))
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{
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base = 16;
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ptr += 2;
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}
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}
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}
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/* If it a hexadecimal representation,
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* than discard any leading "0X" or "0x"
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*/
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else if (base == 16)
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{
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if (ptr[0] == '0' && (ptr[1] == 'X' || ptr[1] == 'x'))
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{
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ptr += 2;
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}
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}
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/* Check for incorrect bases. */
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else if (base < 2 || base > 26)
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{
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return -1; /* Means incorrect base */
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}
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/* Return the updated pointer and base */
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*pptr = ptr;
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return base;
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}
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