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/* |
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* Hardware-accelerated CRC-32 variants for Linux on z Systems |
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* |
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* Use the z/Architecture Vector Extension Facility to accelerate the |
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* computing of bitreflected CRC-32 checksums. |
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* |
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* This CRC-32 implementation algorithm is bitreflected and processes |
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* the least-significant bit first (Little-Endian). |
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* |
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* This code was originally written by Hendrik Brueckner |
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* <[email protected]> for use in the Linux kernel and has been |
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* relicensed under the zlib license. |
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*/ |
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#define Z_ONCE |
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#include "../../zutil.h" |
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#include "crc32_vx_hooks.h" |
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#include <stdint.h> |
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#include <stdio.h> |
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#include <vecintrin.h> |
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#include <sys/auxv.h> |
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#ifdef __clang__ |
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# if ((__clang_major__ == 18) || (__clang_major__ == 19 && (__clang_minor__ < 1 || (__clang_minor__ == 1 && __clang_patchlevel__ < 2)))) |
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# error crc32_vx optimizations are broken due to compiler bug in Clang versions: 18.0.0 <= clang_version < 19.1.2. \ |
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Either disable the zlib crc32_vx optimization, or switch to another compiler/compiler version. |
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# endif |
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#endif |
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#define VX_MIN_LEN 64 |
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#define VX_ALIGNMENT 16L |
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#define VX_ALIGN_MASK (VX_ALIGNMENT - 1) |
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typedef unsigned char uv16qi __attribute__((vector_size(16))); |
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typedef unsigned int uv4si __attribute__((vector_size(16))); |
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typedef unsigned long long uv2di __attribute__((vector_size(16))); |
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local uint32_t crc32_le_vgfm_16(uint32_t crc, const unsigned char *buf, size_t len) { |
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/* |
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* The CRC-32 constant block contains reduction constants to fold and |
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* process particular chunks of the input data stream in parallel. |
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* |
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* For the CRC-32 variants, the constants are precomputed according to |
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* these definitions: |
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* |
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* R1 = [(x4*128+32 mod P'(x) << 32)]' << 1 |
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* R2 = [(x4*128-32 mod P'(x) << 32)]' << 1 |
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* R3 = [(x128+32 mod P'(x) << 32)]' << 1 |
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* R4 = [(x128-32 mod P'(x) << 32)]' << 1 |
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* R5 = [(x64 mod P'(x) << 32)]' << 1 |
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* R6 = [(x32 mod P'(x) << 32)]' << 1 |
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* |
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* The bitreflected Barret reduction constant, u', is defined as |
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* the bit reversal of floor(x**64 / P(x)). |
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* |
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* where P(x) is the polynomial in the normal domain and the P'(x) is the |
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* polynomial in the reversed (bitreflected) domain. |
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* |
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* CRC-32 (IEEE 802.3 Ethernet, ...) polynomials: |
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* |
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* P(x) = 0x04C11DB7 |
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* P'(x) = 0xEDB88320 |
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*/ |
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const uv16qi perm_le2be = {15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0}; /* BE->LE mask */ |
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const uv2di r2r1 = {0x1C6E41596, 0x154442BD4}; /* R2, R1 */ |
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const uv2di r4r3 = {0x0CCAA009E, 0x1751997D0}; /* R4, R3 */ |
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const uv2di r5 = {0, 0x163CD6124}; /* R5 */ |
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const uv2di ru_poly = {0, 0x1F7011641}; /* u' */ |
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const uv2di crc_poly = {0, 0x1DB710641}; /* P'(x) << 1 */ |
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/* |
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* Load the initial CRC value. |
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* |
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* The CRC value is loaded into the rightmost word of the |
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* vector register and is later XORed with the LSB portion |
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* of the loaded input data. |
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*/ |
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uv2di v0 = {0, 0}; |
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v0 = (uv2di)vec_insert(crc, (uv4si)v0, 3); |
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/* Load a 64-byte data chunk and XOR with CRC */ |
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uv2di v1 = vec_perm(((uv2di *)buf)[0], ((uv2di *)buf)[0], perm_le2be); |
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uv2di v2 = vec_perm(((uv2di *)buf)[1], ((uv2di *)buf)[1], perm_le2be); |
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uv2di v3 = vec_perm(((uv2di *)buf)[2], ((uv2di *)buf)[2], perm_le2be); |
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uv2di v4 = vec_perm(((uv2di *)buf)[3], ((uv2di *)buf)[3], perm_le2be); |
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v1 ^= v0; |
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buf += 64; |
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len -= 64; |
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while (len >= 64) { |
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/* Load the next 64-byte data chunk */ |
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uv16qi part1 = vec_perm(((uv16qi *)buf)[0], ((uv16qi *)buf)[0], perm_le2be); |
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uv16qi part2 = vec_perm(((uv16qi *)buf)[1], ((uv16qi *)buf)[1], perm_le2be); |
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uv16qi part3 = vec_perm(((uv16qi *)buf)[2], ((uv16qi *)buf)[2], perm_le2be); |
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uv16qi part4 = vec_perm(((uv16qi *)buf)[3], ((uv16qi *)buf)[3], perm_le2be); |
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/* |
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* Perform a GF(2) multiplication of the doublewords in V1 with |
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* the R1 and R2 reduction constants in V0. The intermediate result |
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* is then folded (accumulated) with the next data chunk in PART1 and |
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* stored in V1. Repeat this step for the register contents |
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* in V2, V3, and V4 respectively. |
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*/ |
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v1 = (uv2di)vec_gfmsum_accum_128(r2r1, v1, part1); |
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v2 = (uv2di)vec_gfmsum_accum_128(r2r1, v2, part2); |
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v3 = (uv2di)vec_gfmsum_accum_128(r2r1, v3, part3); |
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v4 = (uv2di)vec_gfmsum_accum_128(r2r1, v4, part4); |
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buf += 64; |
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len -= 64; |
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} |
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/* |
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* Fold V1 to V4 into a single 128-bit value in V1. Multiply V1 with R3 |
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* and R4 and accumulating the next 128-bit chunk until a single 128-bit |
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* value remains. |
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*/ |
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v1 = (uv2di)vec_gfmsum_accum_128(r4r3, v1, (uv16qi)v2); |
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v1 = (uv2di)vec_gfmsum_accum_128(r4r3, v1, (uv16qi)v3); |
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v1 = (uv2di)vec_gfmsum_accum_128(r4r3, v1, (uv16qi)v4); |
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while (len >= 16) { |
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/* Load next data chunk */ |
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v2 = vec_perm(*(uv2di *)buf, *(uv2di *)buf, perm_le2be); |
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/* Fold next data chunk */ |
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v1 = (uv2di)vec_gfmsum_accum_128(r4r3, v1, (uv16qi)v2); |
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buf += 16; |
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len -= 16; |
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} |
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/* |
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* Set up a vector register for byte shifts. The shift value must |
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* be loaded in bits 1-4 in byte element 7 of a vector register. |
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* Shift by 8 bytes: 0x40 |
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* Shift by 4 bytes: 0x20 |
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*/ |
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uv16qi v9 = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}; |
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v9 = vec_insert((unsigned char)0x40, v9, 7); |
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/* |
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* Prepare V0 for the next GF(2) multiplication: shift V0 by 8 bytes |
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* to move R4 into the rightmost doubleword and set the leftmost |
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* doubleword to 0x1. |
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*/ |
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v0 = vec_srb(r4r3, (uv2di)v9); |
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v0[0] = 1; |
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/* |
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* Compute GF(2) product of V1 and V0. The rightmost doubleword |
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* of V1 is multiplied with R4. The leftmost doubleword of V1 is |
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* multiplied by 0x1 and is then XORed with rightmost product. |
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* Implicitly, the intermediate leftmost product becomes padded |
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*/ |
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v1 = (uv2di)vec_gfmsum_128(v0, v1); |
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/* |
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* Now do the final 32-bit fold by multiplying the rightmost word |
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* in V1 with R5 and XOR the result with the remaining bits in V1. |
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* |
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* To achieve this by a single VGFMAG, right shift V1 by a word |
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* and store the result in V2 which is then accumulated. Use the |
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* vector unpack instruction to load the rightmost half of the |
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* doubleword into the rightmost doubleword element of V1; the other |
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* half is loaded in the leftmost doubleword. |
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* The vector register with CONST_R5 contains the R5 constant in the |
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* rightmost doubleword and the leftmost doubleword is zero to ignore |
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* the leftmost product of V1. |
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*/ |
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v9 = vec_insert((unsigned char)0x20, v9, 7); |
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v2 = vec_srb(v1, (uv2di)v9); |
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v1 = vec_unpackl((uv4si)v1); /* Split rightmost doubleword */ |
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v1 = (uv2di)vec_gfmsum_accum_128(r5, v1, (uv16qi)v2); |
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/* |
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* Apply a Barret reduction to compute the final 32-bit CRC value. |
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* |
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* The input values to the Barret reduction are the degree-63 polynomial |
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* in V1 (R(x)), degree-32 generator polynomial, and the reduction |
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* constant u. The Barret reduction result is the CRC value of R(x) mod |
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* P(x). |
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* |
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* The Barret reduction algorithm is defined as: |
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* |
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* 1. T1(x) = floor( R(x) / x^32 ) GF2MUL u |
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* 2. T2(x) = floor( T1(x) / x^32 ) GF2MUL P(x) |
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* 3. C(x) = R(x) XOR T2(x) mod x^32 |
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* |
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* Note: The leftmost doubleword of vector register containing |
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* CONST_RU_POLY is zero and, thus, the intermediate GF(2) product |
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* is zero and does not contribute to the final result. |
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*/ |
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/* T1(x) = floor( R(x) / x^32 ) GF2MUL u */ |
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v2 = vec_unpackl((uv4si)v1); |
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v2 = (uv2di)vec_gfmsum_128(ru_poly, v2); |
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/* |
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* Compute the GF(2) product of the CRC polynomial with T1(x) in |
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* V2 and XOR the intermediate result, T2(x), with the value in V1. |
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* The final result is stored in word element 2 of V2. |
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*/ |
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v2 = vec_unpackl((uv4si)v2); |
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v2 = (uv2di)vec_gfmsum_accum_128(crc_poly, v2, (uv16qi)v1); |
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return ((uv4si)v2)[2]; |
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} |
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local unsigned long s390_crc32_vx(unsigned long crc, const unsigned char FAR *buf, z_size_t len) |
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{ |
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uintptr_t prealign, aligned, remaining; |
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if (buf == Z_NULL) return 0UL; |
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if (len < VX_MIN_LEN + VX_ALIGN_MASK) |
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return crc32_z(crc, buf, len); |
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if ((uintptr_t)buf & VX_ALIGN_MASK) { |
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prealign = VX_ALIGNMENT - ((uintptr_t)buf & VX_ALIGN_MASK); |
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len -= prealign; |
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crc = crc32_z(crc, buf, prealign); |
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buf += prealign; |
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} |
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aligned = len & ~VX_ALIGN_MASK; |
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remaining = len & VX_ALIGN_MASK; |
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crc = crc32_le_vgfm_16(crc ^ 0xffffffff, buf, (size_t)aligned) ^ 0xffffffff; |
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if (remaining) |
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crc = crc32_z(crc, buf + aligned, remaining); |
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return crc; |
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} |
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local z_once_t s390_crc32_made = Z_ONCE_INIT; |
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local void s390_crc32_setup() { |
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unsigned long hwcap = getauxval(AT_HWCAP); |
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if (hwcap & HWCAP_S390_VX) |
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crc32_z_hook = s390_crc32_vx; |
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else |
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crc32_z_hook = crc32_z; |
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} |
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local unsigned long s390_crc32_init(unsigned long crc, const unsigned char FAR *buf, z_size_t len) |
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{ |
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z_once(&s390_crc32_made,s390_crc32_setup); |
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return crc32_z_hook(crc, buf, len); |
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} |
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ZLIB_INTERNAL unsigned long (*crc32_z_hook)(unsigned long crc, const unsigned char FAR *buf, z_size_t len) = s390_crc32_init; |
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