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109 lines
2.9 KiB
C
109 lines
2.9 KiB
C
/**
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* Character device messaging loop.
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*
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* Copyright (C) 2013, INRIA.
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*
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* This file subject to the terms and conditions of the GNU Lesser General
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* Public License. See the file LICENSE in the top level directory for more
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* details.
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*
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* @ingroup chardev
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* @{
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* @file chardev_thread.c
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* @brief Runs an infinite loop in a separate thread to handle access to character devices such as uart.
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* @author Kaspar Schleiser <kaspar@schleiser.de>
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* @}
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*/
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#include <thread.h>
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#include <kernel.h>
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#include <msg.h>
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#include <ringbuffer.h>
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#include <stdio.h>
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#include <errno.h>
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#include <irq.h>
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#include <posix_io.h>
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//#define ENABLE_DEBUG
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#include <debug.h>
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static int min(int a, int b) {
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if (b>a) return a;
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else return b;
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}
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void chardev_loop(ringbuffer_t *rb) {
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msg_t m;
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int pid = thread_getpid();
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int reader_pid = -1;
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struct posix_iop_t *r = NULL;
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puts("UART0 thread started.");
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while (1) {
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msg_receive(&m);
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if (m.sender_pid != pid) {
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DEBUG("Receiving message from another thread\n");
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switch (m.type) {
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case OPEN:
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if (reader_pid == -1) {
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reader_pid = m.sender_pid;
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/* no error */
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m.content.value = 0;
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}
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else {
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m.content.value = -EBUSY;
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}
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msg_reply(&m,&m);
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break;
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case READ:
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if (m.sender_pid != reader_pid) {
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m.content.value = -EINVAL;
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r = NULL;
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msg_reply(&m, &m);
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}
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else {
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r = (struct posix_iop_t *)m.content.ptr;
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}
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break;
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case CLOSE:
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if (m.sender_pid == reader_pid) {
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DEBUG("uart0_thread: closing file from %i\n", reader_pid);
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reader_pid = -1;
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r = NULL;
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m.content.value = 0;
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}
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else {
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m.content.value = -EINVAL;
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}
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msg_reply(&m,&m);
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break;
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default:
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m.content.value = -EINVAL;
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msg_reply(&m, &m);
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}
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}
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if (rb->avail && (r != NULL)) {
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int state = disableIRQ();
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int nbytes = min(r->nbytes, rb->avail);
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DEBUG("uart0_thread [%i]: sending %i bytes received from %i to pid %i\n", pid, nbytes, m.sender_pid, reader_pid);
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rb_get_elements(rb, r->buffer, nbytes);
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r->nbytes = nbytes;
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m.sender_pid = reader_pid;
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m.type = OPEN;
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m.content.ptr = (char*)r;
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msg_reply(&m, &m);
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r = NULL;
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restoreIRQ(state);
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}
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}
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}
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