siphash_rng.c

/* Copyright (c) 2020 tevador <tevador@gmail.com> */
/* See LICENSE for licensing information */
 
#include "siphash_rng.h"
 
void hashx_siphash_rng_init(siphash_rng* gen, const siphash_state* state) {
        gen->keys = *state;
        gen->counter = 0;
        gen->count8 = 0;
        gen->count32 = 0;
}
 
uint8_t hashx_siphash_rng_u8(siphash_rng* gen) {
        if (gen->count8 == 0) {
                gen->buffer8 = hashx_siphash13_ctr(gen->counter, &gen->keys);
                gen->counter++;
                gen->count8 = sizeof(gen->buffer8);
#ifdef HASHX_RNG_CALLBACK
                if (gen->callback) {
                        gen->callback(&gen->buffer8, gen->callback_user_data);
                }
#endif
        }
        gen->count8--;
        return gen->buffer8 >> (gen->count8 * 8);
}
 
uint32_t hashx_siphash_rng_u32(siphash_rng* gen) {
        if (gen->count32 == 0) {
                gen->buffer32 = hashx_siphash13_ctr(gen->counter, &gen->keys);
                gen->counter++;
                gen->count32 = sizeof(gen->buffer32) / sizeof(uint32_t);
#ifdef HASHX_RNG_CALLBACK
                if (gen->callback) {
                        gen->callback(&gen->buffer32, gen->callback_user_data);
                }
#endif
        }
        gen->count32--;
        return (uint32_t)(gen->buffer32 >> (gen->count32 * 32));
}