Тот же пример на Си

[vak]

Часть вторая: то же самое, но без Верилога.
Подробности будут в третьей части. Текст на Си:

#include <stdio.h>
#include "rtlsim.h"

signal_t clock  = signal_init ("clock",  0); /* Main clock of the design */
signal_t reset  = signal_init ("reset",  0); /* Active high, synchronous Reset */
signal_t enable = signal_init ("enable", 0); /* Active high enable signal for counter */
signal_t count  = signal_init ("count",  0); /* 4-bit counter */

void do_clock ()
{
    for (;;) {
        signal_set (&clock, 0);
        process_delay (10);
        signal_set (&clock, 1);
        process_delay (10);
    }
}

void do_counter ()
{
    /* Make a sensitivity list. */
    process_sensitive (&clock, POSEDGE);

    for (;;) {
        /* Wait for event from the sensitivity list. */
        process_wait();

        /* At every rising edge of clock we check if reset is active.
         * If active, we load the counter output with 4'b0000. */
        if (reset.value != 0) {
            signal_set (&count, 0);

        /* If enable is active, then we increment the counter. */
        } else if (enable.value != 0) {
            printf ("(%llu) Incremented Counter %llu\n", time_ticks, count.value);
            signal_set (&count, (count.value + 1) & 15);
        }
    }
}

int main (int argc, char **argv)
{
    /* Create processes with 4kbyte stacks. */
    process_init ("clock", do_clock, 4096);
    process_init ("counter", do_counter, 4096);

    process_delay (100);
    signal_set (&reset, 1);
    printf ("(%llu) Asserting Reset\n", time_ticks);

    process_delay (200);
    signal_set (&reset, 0);
    printf ("(%llu) De-Asserting Reset\n", time_ticks);

    process_delay (100);
    printf ("(%llu) Asserting Enable\n", time_ticks);
    signal_set (&enable, 1);

    process_delay (400);
    printf ("(%llu) De-Asserting Enable\n", time_ticks);
    signal_set (&enable, 0);

    printf ("(%llu) Terminating simulation\n", time_ticks);
    return 0;
}

Запускаем:

$ make
cc -c -o example.o example.c
cc -c -o rtlsim.o rtlsim.c
cc -o example example.o rtlsim.o
$ ./example
(100) Asserting Reset
(300) De-Asserting Reset
(400) Asserting Enable
(410) Incremented Counter 0
(430) Incremented Counter 1
(450) Incremented Counter 2
(470) Incremented Counter 3
(490) Incremented Counter 4
(510) Incremented Counter 5
(530) Incremented Counter 6
(550) Incremented Counter 7
(570) Incremented Counter 8
(590) Incremented Counter 9
(610) Incremented Counter 10
(630) Incremented Counter 11
(650) Incremented Counter 12
(670) Incremented Counter 13
(690) Incremented Counter 14
(710) Incremented Counter 15
(730) Incremented Counter 0
(750) Incremented Counter 1
(770) Incremented Counter 2
(790) Incremented Counter 3
(800) De-Asserting Enable
(800) Terminating simulation
$ _