1 // SPDX-License-Identifier: GPL-2.0-only
9 #include <asm/alternative-macros.h>
20  * Refer to https://www.corsix.org/content/barrett-reduction-polynomials for
24  * let "-" denotes polynomial sub (XOR)
29  * let "T" denotes 2^(XLEN+32)
33  * => S * (2^32) - S * (2^32) / P * P
34  * => lowest 32 bits of: S * (2^32) / P * P
35  * => lowest 32 bits of: S * (2^32) * (T / P) / T * P
36  * => lowest 32 bits of: S * (2^32) * quotient / T * P
37  * => lowest 32 bits of: S * quotient / 2^XLEN * P
38  * => lowest 32 bits of: (clmul_high_part(S, QT) + S) * P
46 /* Slide by XLEN bits per iteration */
51 /* Polynomial quotient of (2^(XLEN+32))/CRC32_POLY, in LE format */
54 /* Polynomial quotient of (2^(XLEN+32))/CRC32C_POLY, in LE format */
57 /* Polynomial quotient of (2^(XLEN+32))/CRC32_POLY, in BE format, it should be
58  * the same as the bit-reversed version of CRC32_POLY_QT_LE
78 		      "srli	%0, %0, 32\n"  in crc32_le_zbc()
83 			"r" ((u64)poly << 32)  in crc32_le_zbc()
90 	return ((u64)crc << 32) ^ (__force u64)__cpu_to_be64(*ptr);  in crc32_be_prep()
93 #elif __riscv_xlen == 32
153 #define OFFSET_MASK	(STEP - 1)
161 	size_t bits = len * 8;  in crc32_le_unaligned()  local
166 		s = ((unsigned long)*p++ << (__riscv_xlen - 8)) | (s >> 8);  in crc32_le_unaligned()
168 	s ^= (unsigned long)crc << (__riscv_xlen - bits);  in crc32_le_unaligned()
169 	if (__riscv_xlen == 32 || len < sizeof(u32))  in crc32_le_unaligned()
170 		crc_low = crc >> bits;  in crc32_le_unaligned()
194 		head_len = min(STEP - offset, len);  in crc32_le_generic()
197 		len -= head_len;  in crc32_le_generic()
238 	size_t bits = len * 8;  in crc32_be_unaligned()  local
246 	if (__riscv_xlen == 32 || len < sizeof(u32)) {  in crc32_be_unaligned()
247 		s ^= crc >> (32 - bits);  in crc32_be_unaligned()
248 		crc_low = crc << bits;  in crc32_be_unaligned()
250 		s ^= (unsigned long)crc << (bits - 32);  in crc32_be_unaligned()
272 		head_len = min(STEP - offset, len);  in crc32_be_arch()
275 		len -= head_len;  in crc32_be_arch()