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#include <linux/kernel.h>
enum poolinfo {
POOL_WORDS = 128,
POOL_WORDMASK = POOL_WORDS - 1,
POOL_BITS = POOL_WORDS * sizeof(u32) * 8,
/* x^128 + x^104 + x^76 + x^51 +x^25 + x + 1 */
POOL_TAP1 = 104,
POOL_TAP2 = 76,
POOL_TAP3 = 51,
POOL_TAP4 = 25,
POOL_TAP5 = 1,
};
static u32 input_pool_data[POOL_WORDS];
static struct {
u16 add_ptr;
u16 input_rotate;
} input_pool = { 0 };
void mix_crc32loop(const void *in, int nbytes)
{
unsigned long i, j;
int input_rotate;
const u8 *bytes = in;
u32 w;
input_rotate = input_pool.input_rotate;
i = input_pool.add_ptr;
/* mix one byte at a time to simplify size handling and churn faster */
while (nbytes--) {
w = rol32(*bytes++, input_rotate);
i = (i - 1) & POOL_WORDMASK;
/* XOR in the various taps */
w ^= input_pool_data[i];
w ^= input_pool_data[(i + POOL_TAP1) & POOL_WORDMASK];
w ^= input_pool_data[(i + POOL_TAP2) & POOL_WORDMASK];
w ^= input_pool_data[(i + POOL_TAP3) & POOL_WORDMASK];
w ^= input_pool_data[(i + POOL_TAP4) & POOL_WORDMASK];
w ^= input_pool_data[(i + POOL_TAP5) & POOL_WORDMASK];
/* Mix the result back in with a twist */
for (j = 0; j < 3; ++j)
w = (w >> 1) ^ (0xedb88320 & -(w & 1));
input_pool_data[i] = w;
/*
* Normally, we add 7 bits of rotation to the pool.
* At the beginning of the pool, add an extra 7 bits
* rotation, so that successive passes spread the
* input bits across the pool evenly.
*/
input_rotate = (input_rotate + (i ? 7 : 14)) & 31;
}
input_pool.input_rotate = input_rotate;
input_pool.add_ptr = i;
}
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