s390/crypto/crc32be-vx.c

1 /* SPDX-License-Identifier: GPL-2.0 */
3  * Hardware-accelerated CRC-32 variants for Linux on z Systems
6  * computing of CRC-32 checksums.
8  * This CRC-32 implementation algorithm processes the most-significant
9  * bit first (BE).
17 #include "crc32-vx.h"
19 /* Vector register range containing CRC-32 constants */
28  * The CRC-32 constant block contains reduction constants to fold and
31  * For the CRC-32 variants, the constants are precomputed according to
34  *	R1 = x4*128+64 mod P(x)
36  *	R3 = x128+64   mod P(x)
41  *	Barret reduction constant, u, is defined as floor(x**64 / P(x)).
52  * CRC-32 (IEEE 802.3 Ethernet, ...) polynomials:
68  * crc32_be_vgfm_16 - Compute CRC-32 (BE variant) with vector registers
72  * @size: Size of the buffer, must be 64 bytes or greater.
78  *	V9..V14: CRC-32 constants.
82 	/* Load CRC-32 constants */  in crc32_be_vgfm_16()
89 	/* Load a 64-byte data chunk and XOR with CRC */  in crc32_be_vgfm_16()
92 	buf += 64;  in crc32_be_vgfm_16()
93 	size -= 64;  in crc32_be_vgfm_16()
95 	while (size >= 64) {  in crc32_be_vgfm_16()
96 		/* Load the next 64-byte data chunk into V5 to V8 */  in crc32_be_vgfm_16()
110 		buf += 64;  in crc32_be_vgfm_16()
111 		size -= 64;  in crc32_be_vgfm_16()
114 	/* Fold V1 to V4 into a single 128-bit value in V1 */  in crc32_be_vgfm_16()
123 		size -= 16;  in crc32_be_vgfm_16()
127 	 * The R5 constant is used to fold a 128-bit value into an 96-bit value  in crc32_be_vgfm_16()
128 	 * that is XORed with the next 96-bit input data chunk.  To use a single  in crc32_be_vgfm_16()
129 	 * VGFMG instruction, multiply the rightmost 64-bit with x^32 (1<<32) to  in crc32_be_vgfm_16()
130 	 * form an intermediate 96-bit value (with appended zeros) which is then  in crc32_be_vgfm_16()
136 	 * Further reduce the remaining 96-bit value to a 64-bit value using a  in crc32_be_vgfm_16()
139 	 * doubleword with R6.	The result is a 64-bit value and is subject to  in crc32_be_vgfm_16()
145 	 * The input values to the Barret reduction are the degree-63 polynomial  in crc32_be_vgfm_16()
146 	 * in V1 (R(x)), degree-32 generator polynomial, and the reduction  in crc32_be_vgfm_16()