dynamic_hash.h

/*
 * SPDX-FileCopyrightText: 2024 The P4 Language Consortium
 *
 * SPDX-License-Identifier: Apache-2.0
 */
 
#ifndef BACKENDS_TOFINO_BF_UTILS_DYNAMIC_HASH_DYNAMIC_HASH_H_
#define BACKENDS_TOFINO_BF_UTILS_DYNAMIC_HASH_DYNAMIC_HASH_H_
 
#include <cstdint>
 
#include "backends/tofino/bf-utils/dynamic_hash/bfn_hash_algorithm.h"
 
#ifdef __cplusplus
extern "C" {
#endif
 
#define PARITY_GROUPS_DYN 16
#define HASH_MATRIX_WIDTH_DYN 52
#define HASH_SEED_LENGTH 64
/* 128 crossbar bytes divided by 16 parity groups divided by 2 per byte pair */
#define BYTE_PAIRS_PER_PARITY_GROUP 4
 
enum ixbar_input_type { tCONST, tPHV };

typedef struct hash_symmetric_info_ {
    /* Whether this bit-range is symmetric */
    bool is_symmetric;
    /* The symmetric group for this hash input */
    uint32_t sym_group;
    /* The symmetric group which this hash input
     * needs to be symmetrically hashed with */
    uint32_t sib_sym_group;
} hash_symmetric_info_t;

typedef struct ixbar_input_ {
    enum ixbar_input_type type;
    uint32_t ixbar_bit_position;
    uint32_t bit_size;
    hash_symmetric_info_t symmetric_info;
    union {
        bool valid;
        uint64_t constant;
    } u;
} ixbar_input_t;

typedef struct hash_calc_output_ {
    uint32_t p4_hash_output_bit;
    uint32_t gfm_start_bit;
    uint32_t bit_size;
} hash_matrix_output_t;

typedef struct hash_calc_rotate_info {
    uint64_t rotate;
    uint32_t num_hash_bits;
    uint32_t *gfm_bit_posn;
    uint32_t *p4_hash_output_bit_posn;
} hash_calc_rotate_info_t;

typedef struct ixbar_init_ {
    ixbar_input_t *ixbar_inputs;
    uint32_t inputs_sz;
 
    hash_matrix_output_t *hash_matrix_outputs;
    uint32_t outputs_sz;
 
    uint32_t parity_group;
} ixbar_init_t;

typedef struct hash_column_ {
    uint64_t column_value;
    uint8_t byte_used;
} hash_column_t;

typedef struct hash_seed_ {
    uint64_t hash_seed_value;
    uint64_t hash_seed_used;
} hash_seed_t;

typedef struct galois_field_matrix_delta_ {
    uint32_t byte_pair_index;
    uint32_t hash_bit;
 
    unsigned byte0;
    unsigned valid0;
    unsigned byte1;
    unsigned valid1;
} galois_field_matrix_delta_t;

typedef struct hash_seed_delta_ {
    uint32_t hash_bit;
    unsigned hash_seed_and_value;
    unsigned hash_seed_or_value;
} hash_seed_delta_t;

typedef struct hash_regs_ {
    // This field must be freed after use
    galois_field_matrix_delta_t *galois_field_matrix_regs;
    uint32_t gfm_sz;
 
    // This field must be freed after use
    hash_seed_delta_t *hash_seed_regs;
    uint32_t hs_sz;
} hash_regs_t;

void determine_hash_matrix(const ixbar_init_t *ixbar_init, const ixbar_input_t *inputs,
                           uint32_t inputs_sz, const bfn_hash_algorithm_t *alg,
                           hash_column_t hash_matrix[PARITY_GROUPS_DYN][HASH_MATRIX_WIDTH_DYN]);
void determine_seed(const hash_matrix_output_t *hash_matrix_outputs, uint32_t outputs_sz,
                    const ixbar_input_t *inputs, uint32_t inputs_sz, uint32_t total_input_bits,
                    const bfn_hash_algorithm_t *alg, hash_seed_t *hash_seed);

void determine_tofino_regs(const ixbar_init_t *ixbar_init, const ixbar_input_t *inputs,
                           uint32_t input_sz, const bfn_hash_algorithm_t *alg,
                           hash_calc_rotate_info_t *rot_info, hash_regs_t *hash_regs);
 
#ifdef __cplusplus
}
#endif
 
#endif /* BACKENDS_TOFINO_BF_UTILS_DYNAMIC_HASH_DYNAMIC_HASH_H_ */