lupio_rng.cc

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/*
 * Copyright (c) 2021 The Regents of the University of California
 * All rights reserved.
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#include "dev/lupio/lupio_rng.hh"
 
#include <random>
 
#include "debug/LupioRNG.hh"
#include "mem/packet_access.hh"
#include "params/LupioRNG.hh"
 
/* CTRL fields */
#define LUPIO_RNG_IRQE  0x1
/* STAT fields */
#define LUPIO_RNG_BUSY  0x1
 
namespace gem5
{
 
LupioRNG::LupioRNG(const Params &params) :
    BasicPioDevice(params, params.pio_size),
    user_seed(params.seed)
{
    mt.seed(user_seed);
    DPRINTF(LupioRNG, "LupioRNG initalized with seed: %d\n", user_seed);
}
 
uint64_t
LupioRNG::lupioRNGRead(uint8_t addr)
{
    uint32_t r = 0;
    std::uniform_int_distribution<uint32_t> distrib(0);
 
    switch (addr >> 2) {
        // returns a random number
        case LUPIO_RNG_RAND:
            r = distrib(mt);
            DPRINTF(LupioRNG, "Random number: %#x\n", r );
            break;
        // returns the current seed being used
        case LUPIO_RNG_SEED:
            r = user_seed;
            DPRINTF(LupioRNG, "RNG_SEED Call: %d\n", r);
            break;
        // returns status of the device
        case LUPIO_RNG_STAT:
            r = 0;  /* Always ready */
            DPRINTF(LupioRNG, "RNG_STAT Call: %d\n", r);
            break;
        default:
            r = -1;
            panic("Unexpected read to the LupioRTC device at address %d!",
                    addr);
            break;
    }
    return r;
}
 
void
LupioRNG::lupioRNGWrite(uint8_t addr, uint64_t val64)
{
    switch (addr >> 2) {
        // allows the user to configure the seed value
        case LUPIO_RNG_SEED:
            user_seed = val64;
            mt.seed(user_seed);
            DPRINTF(LupioRNG, "RNG_SEED_WRITE: %d\n", user_seed);
            break;
        // configures the device using interrupts
        case LUPIO_RNG_CTRL:
            interrupt_enable = !!(val64 & LUPIO_RNG_IRQE);
            DPRINTF(LupioRNG, "RNG_CTRL Call: %d\n", interrupt_enable);
            break;
        default:
            panic("Unexpected write to the LupioRTC device at address %d!",
                    addr);
            break;
    }
}
 
Tick
LupioRNG::read(PacketPtr pkt)
{
    Addr rng_addr = pkt->getAddr() - pioAddr;
 
    DPRINTF(LupioRNG,
        "Read request - addr: %#x, size: %#x\n", rng_addr, pkt->getSize());
 
    uint64_t rand_read = lupioRNGRead(rng_addr);
    DPRINTF(LupioRNG, "Packet Read: %#x\n", rand_read);
    pkt->setUintX(rand_read, byteOrder);
    pkt->makeResponse();
 
    return pioDelay;
}
 
Tick
LupioRNG::write(PacketPtr pkt)
{
    Addr daddr = pkt->getAddr() - pioAddr;
 
    DPRINTF(LupioRNG, "Write register %#x value %#x\n", daddr,
            pkt->getUintX(byteOrder));
 
    lupioRNGWrite(daddr, pkt->getUintX(byteOrder));
    DPRINTF(LupioRNG, "Packet Write Value: %d\n", pkt->getUintX(byteOrder));
 
    pkt->makeResponse();
 
    return pioDelay;
}
} // namespace gem5