sdk-bsp-psoc_e84-edgi-talk/rt-thread/examples/libc/ex2.c

/*
 * Copyright (c) 2006-2021, RT-Thread Development Team
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Change Logs:
 * Date           Author       Notes
 */
/* The classic producer-consumer example.
   Illustrates mutexes and conditions.
   All integers between 0 and 9999 should be printed exactly twice,
   once to the right of the arrow and once to the left. */

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

#define BUFFER_SIZE 16

/* Circular buffer of integers. */

struct prodcons
{
    int buffer[BUFFER_SIZE];      /* the actual data */
    pthread_mutex_t lock;         /* mutex ensuring exclusive access to buffer */
    int readpos, writepos;        /* positions for reading and writing */
    pthread_cond_t notempty;      /* signaled when buffer is not empty */
    pthread_cond_t notfull;       /* signaled when buffer is not full */
};

/* Initialize a buffer */

static void init(struct prodcons * b)
{
    pthread_mutex_init(&b->lock, NULL);
    pthread_cond_init(&b->notempty, NULL);
    pthread_cond_init(&b->notfull, NULL);
    b->readpos = 0;
    b->writepos = 0;
}

/* Store an integer in the buffer */
static void put(struct prodcons * b, int data)
{
    pthread_mutex_lock(&b->lock);
    /* Wait until buffer is not full */
    while ((b->writepos + 1) % BUFFER_SIZE == b->readpos)
    {
        pthread_cond_wait(&b->notfull, &b->lock);
        /* pthread_cond_wait reacquired b->lock before returning */
    }
    /* Write the data and advance write pointer */
    b->buffer[b->writepos] = data;
    b->writepos++;
    if (b->writepos >= BUFFER_SIZE) b->writepos = 0;
    /* Signal that the buffer is now not empty */
    pthread_cond_signal(&b->notempty);
    pthread_mutex_unlock(&b->lock);
}

/* Read and remove an integer from the buffer */

static int get(struct prodcons * b)
{
    int data;
    pthread_mutex_lock(&b->lock);
    /* Wait until buffer is not empty */
    while (b->writepos == b->readpos)
    {
        pthread_cond_wait(&b->notempty, &b->lock);
    }
    /* Read the data and advance read pointer */
    data = b->buffer[b->readpos];
    b->readpos++;
    if (b->readpos >= BUFFER_SIZE) b->readpos = 0;
    /* Signal that the buffer is now not full */
    pthread_cond_signal(&b->notfull);
    pthread_mutex_unlock(&b->lock);
    return data;
}

/* A test program: one thread inserts integers from 1 to 10000,
   the other reads them and prints them. */

#define OVER (-1)

struct prodcons buffer;

static void *producer(void * data)
{
    int n;
    for (n = 0; n < 10000; n++)
    {
        printf("%d --->\n", n);
        put(&buffer, n);
    }
    put(&buffer, OVER);
    return NULL;
}

static void *consumer(void * data)
{
    int d;
    while (1)
    {
        d = get(&buffer);
        if (d == OVER) break;
        printf("---> %d\n", d);
    }
    return NULL;
}

int libc_ex2(void)
{
    pthread_t th_a, th_b;
    void *retval;

    init(&buffer);
    /* Create the threads */
    pthread_create(&th_a, NULL, producer, 0);
    pthread_create(&th_b, NULL, consumer, 0);
    /* Wait until producer and consumer finish. */
    pthread_join(th_a, &retval);
    pthread_join(th_b, &retval);
    return 0;
}
#include <finsh.h>
FINSH_FUNCTION_EXPORT(libc_ex2, example 2 for libc);