stdlib.c

linux 内核源代码

/*
 * stdlib functions
 *
 * Author: Scott Wood <[e-mail]>
 *
 * Copyright (c) 2007 Freescale Semiconductor, Inc.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 */

#include "stdlib.h"

/* Not currently supported: leading whitespace, sign, 0x prefix, zero base */
unsigned long long int strtoull(const char *ptr, char **end, int base)
{
	unsigned long long ret = 0;

	if (base > 36)
		goto out;

	while (*ptr) {
		int digit;

		if (*ptr >= '0' && *ptr <= '9' && *ptr < '0' + base)
			digit = *ptr - '0';
		else if (*ptr >= 'A' && *ptr < 'A' + base - 10)
			digit = *ptr - 'A' + 10;
		else if (*ptr >= 'a' && *ptr < 'a' + base - 10)
			digit = *ptr - 'a' + 10;
		else
			break;

		ret *= base;
		ret += digit;
		ptr++;
	}

out:
	if (end)
		*end = (char *)ptr;

	return ret;
}