atoi函数的实现二: 测试各实现的正确性

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#include <ctype.h>
#include <string.h>
#include <stdio.h>

/*http://lxr.free-electrons.com/source/lib/kstrtox.h#L4*/
#define KSTRTOX_OVERFLOW        (1U << 31)
const char *_parse_integer_fixup_radix(const char *s, unsigned int *base);
unsigned int _parse_integer(const char *s, unsigned int base, unsigned long long *res);

/*http://lxr.free-electrons.com/source/arch/powerpc/boot/types.h#L12*/
typedef int                     s32;
typedef unsigned int            u32;
typedef unsigned long long      u64;

/*http://lxr.free-electrons.com/source/drivers/media/pci/ngene/ngene-dvb.c#L127*/
static u32 overflow;

/*http://lxr.free-electrons.com/source/include/linux/kernel.h#L29*/
#define ULLONG_MAX      (~0ULL)

#define unlikely(cond) (cond)

/*http://lxr.free-electrons.com/source/lib/kstrtox.c#L23*/
const char *_parse_integer_fixup_radix(const char *s, unsigned int *base)
{
        if (*base == 0) {
                if (s[0] == '0') {
                        if (_tolower(s[1]) == 'x' && isxdigit(s[2]))
                                *base = 16;
                        else
                                *base = 8;
                } else
                        *base = 10;
        }
        if (*base == 16 && s[0] == '0' && _tolower(s[1]) == 'x')
                s += 2;
        return s;
}

/*http://lxr.free-electrons.com/source/lib/kstrtox.c#L47*/
/*
 * Convert non-negative integer string representation in explicitly given radix
 * to an integer.
 * Return number of characters consumed maybe or-ed with overflow bit.
 * If overflow occurs, result integer (incorrect) is still returned.
 *
 * Don't you dare use this function.
 */
unsigned int _parse_integer(const char *s, unsigned int base, unsigned long long *p)
{
        unsigned long long res;
        unsigned int rv;
        int overflow;

        res = 0;
        rv = 0;
        overflow = 0;
        while (*s) {
                unsigned int val;

                if ('0' <= *s && *s <= '9')
                        val = *s - '0';
                else if ('a' <= _tolower(*s) && _tolower(*s) <= 'f')
                        val = _tolower(*s) - 'a' + 10;
                else
                        break;

                if (val >= base)
                        break;
                /*
                 * Check for overflow only if we are within range of
                 * it in the max base we support (16)
                 */
                if (unlikely(res & (~0ull << 60))) {
                        if (res > ULLONG_MAX - val/base)
                                overflow = 1;
                }
                res = res * base + val;
                rv++;
                s++;
        }
        *p = res;
        if (overflow)
                rv |= KSTRTOX_OVERFLOW;
        return rv;
}

/*http://lxr.free-electrons.com/source/lib/vsprintf.c#L44*/
/**
 * simple_strtoull - convert a string to an unsigned long long
 * @cp: The start of the string
 * @endp: A pointer to the end of the parsed string will be placed here
 * @base: The number base to use
 *
 * This function is obsolete. Please use kstrtoull instead.
 */
unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base)
{
        unsigned long long result;
        unsigned int rv;

        cp = _parse_integer_fixup_radix(cp, &base);
        rv = _parse_integer(cp, base, &result);
        /* FIXME */
        cp += (rv & ~KSTRTOX_OVERFLOW);

        if (endp)
                *endp = (char *)cp;

        return result;
}

/*http://lxr.free-electrons.com/source/lib/vsprintf.c#L83*/
/**
 * simple_strtoul - convert a string to an unsigned long
 * @cp: The start of the string
 * @endp: A pointer to the end of the parsed string will be placed here
 * @base: The number base to use
 *
 * This function is obsolete. Please use kstrtoul instead.
 */
unsigned long simple_strtoul(const char *cp, char **endp, unsigned int base)
{
        return simple_strtoull(cp, endp, base);
}

/*http://lxr.free-electrons.com/source/drivers/staging/tidspbridge/rmgr/dbdcd.c#L950*/
/*
 *  ======== atoi ========
 *  Purpose:
 *      This function converts strings in decimal or hex format to integers.
 */
static s32 matoi(const char *psz_buf)
{
        char *pch = psz_buf;
        s32 base = 0;

        while (isspace(*pch))
                pch++;

        if (*pch == '-' || *pch == '+') {
                base = 10;
                pch++;
        } else if (*pch && tolower(pch[strlen(pch) - 1]) == 'h') {
                base = 16;
        }

        return simple_strtoul(pch, NULL, base);
}

void test(const char* str) {
    printf("%s : %d\n", str, matoi(str));
}

int main() {
    test("2147483647");
    test("2147483648");
    test("-2147483648");
    test("-2147483649");
    test("10522545459");
    test("-10522545459");

    return 0;
}

atoi函数的实现二: 测试各实现的正确性

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