mirror of
https://github.com/opencv/opencv.git
synced 2024-11-27 12:40:05 +08:00
0de26fd78e
Zlib-ng is zlib replacement with optimizations for "next generation" systems. Its optimization may benifits image library decode and encode speed such as libpng. In our tests, if using zlib-ng and libpng combination on a x86_64 machine with AVX2, the time of `imdecode` amd `imencode` will drop 20% approximately. This patch enables zlib-ng's optimization if `CV_DISABLE_OPTIMIZATION` is OFF. Since Zlib-ng can dispatch intrinsics on the fly, port work is much easier. Related discussion: https://github.com/opencv/opencv/issues/22573
43 lines
908 B
C
43 lines
908 B
C
#ifndef CRC32_BRAID_COMB_P_H_
|
|
#define CRC32_BRAID_COMB_P_H_
|
|
|
|
/*
|
|
Return a(x) multiplied by b(x) modulo p(x), where p(x) is the CRC polynomial,
|
|
reflected. For speed, this requires that a not be zero.
|
|
*/
|
|
static uint32_t multmodp(uint32_t a, uint32_t b) {
|
|
uint32_t m, p;
|
|
|
|
m = (uint32_t)1 << 31;
|
|
p = 0;
|
|
for (;;) {
|
|
if (a & m) {
|
|
p ^= b;
|
|
if ((a & (m - 1)) == 0)
|
|
break;
|
|
}
|
|
m >>= 1;
|
|
b = b & 1 ? (b >> 1) ^ POLY : b >> 1;
|
|
}
|
|
return p;
|
|
}
|
|
|
|
/*
|
|
Return x^(n * 2^k) modulo p(x). Requires that x2n_table[] has been
|
|
initialized.
|
|
*/
|
|
static uint32_t x2nmodp(z_off64_t n, unsigned k) {
|
|
uint32_t p;
|
|
|
|
p = (uint32_t)1 << 31; /* x^0 == 1 */
|
|
while (n) {
|
|
if (n & 1)
|
|
p = multmodp(x2n_table[k & 31], p);
|
|
n >>= 1;
|
|
k++;
|
|
}
|
|
return p;
|
|
}
|
|
|
|
#endif /* CRC32_BRAID_COMB_P_H_ */
|