c - 使用 gcc 编译时出错

Question

下面的代码在编译时给出了这个错误我不明白为什么会这样。 switch语句的每一行都有这个错误。这段代码取自用 g++ 完美编译的代码，但我不明白 gcc 有什么问题。

void 
str_murmurhash3_x64_128 ( const void * key, const int len,
                           const uint32_t seed, void * out )
{
    const uint8_t * data = (const uint8_t*)key;
    const int nblocks = len / 16;

    uint64_t h1 = seed;
    uint64_t h2 = seed;

    uint64_t c1 = BIG_CONSTANT(0x87c37b91114253d5);
    uint64_t c2 = BIG_CONSTANT(0x4cf5ad432745937f);

    //----------
    // body

    const uint64_t * blocks = (const uint64_t *)(data);
    int i;
    for(i = 0; i < nblocks; i++)
    {
        uint64_t k1 = getblock(blocks,i*2+0);
        uint64_t k2 = getblock(blocks,i*2+1);

        k1 *= c1; k1  = ROTL64(k1,31); k1 *= c2; h1 ^= k1;

        h1 = ROTL64(h1,27); h1 += h2; h1 = h1*5+0x52dce729;

        k2 *= c2; k2  = ROTL64(k2,33); k2 *= c1; h2 ^= k2;

        h2 = ROTL64(h2,31); h2 += h1; h2 = h2*5+0x38495ab5;
    }

    //----------
    // tail

    const uint8_t * tail = (const uint8_t*)(data + nblocks*16);

    uint64_t k1 = 0;
    uint64_t k2 = 0;

    switch(len & 15)
    {
        case 15: k2 ^= uint64_t(tail[14]) << 48;
        case 14: k2 ^= uint64_t(tail[13]) << 40;
        case 13: k2 ^= uint64_t(tail[12]) << 32;
        case 12: k2 ^= uint64_t(tail[11]) << 24;
        case 11: k2 ^= uint64_t(tail[10]) << 16;
        case 10: k2 ^= uint64_t(tail[ 9]) << 8;
        case  9: k2 ^= uint64_t(tail[ 8]) << 0;
                k2 *= c2; k2  = ROTL64(k2,33); k2 *= c1; h2 ^= k2;

        case  8: k1 ^= uint64_t(tail[ 7]) << 56;
        case  7: k1 ^= uint64_t(tail[ 6]) << 48;
        case  6: k1 ^= uint64_t(tail[ 5]) << 40;
        case  5: k1 ^= uint64_t(tail[ 4]) << 32;
        case  4: k1 ^= uint64_t(tail[ 3]) << 24;
        case  3: k1 ^= uint64_t(tail[ 2]) << 16;
        case  2: k1 ^= uint64_t(tail[ 1]) << 8;
        case  1: k1 ^= uint64_t(tail[ 0]) << 0;
                k1 *= c1; k1  = ROTL64(k1,31); k1 *= c2; h1 ^= k1;
    };

    //----------
    // finalization

    h1 ^= len; h2 ^= len;

    h1 += h2;
    h2 += h1;

    h1 = fmix(h1);
    h2 = fmix(h2);

    h1 += h2;
    h2 += h1;

    ((uint64_t*)out)[0] = h1;
    ((uint64_t*)out)[1] = h2;
}

以下是错误，错误中指定的所有行号都对应于 switch case 中的行。

murmurhash3.c:103:18: error: expected expression before ‘uint64_t’
murmurhash3.c:104:18: error: expected expression before ‘uint64_t’
murmurhash3.c:105:18: error: expected expression before ‘uint64_t’
murmurhash3.c:106:18: error: expected expression before ‘uint64_t’
murmurhash3.c:107:18: error: expected expression before ‘uint64_t’
murmurhash3.c:108:18: error: expected expression before ‘uint64_t’
murmurhash3.c:109:18: error: expected expression before ‘uint64_t’
murmurhash3.c:112:18: error: expected expression before ‘uint64_t’
murmurhash3.c:113:18: error: expected expression before ‘uint64_t’
murmurhash3.c:114:18: error: expected expression before ‘uint64_t’
murmurhash3.c:115:18: error: expected expression before ‘uint64_t’
murmurhash3.c:116:18: error: expected expression before ‘uint64_t’
murmurhash3.c:117:18: error: expected expression before ‘uint64_t’
murmurhash3.c:118:18: error: expected expression before ‘uint64_t’
murmurhash3.c:119:18: error: expected expression before ‘uint64_t’

感谢任何帮助。

Answer 1

语法错误:

case 15: k2 ^= uint64_t(tail[14]) << 48;

试试这个:

case 15: k2 ^= ((uint64_t)tail[14]) << 48;

另外，你想要 fall-through 行为吗？如果不是，请在每个 case 语句后添加 break;。