172 lines
4.2 KiB
C
172 lines
4.2 KiB
C
/*
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Copyright (C) 2015 Andrea Zoppi
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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#include "ch.h"
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#include "hal.h"
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#include "tribuf.h"
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#include <stdio.h>
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#include <stdlib.h>
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/*===========================================================================*/
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/* TriBuf related. */
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/*===========================================================================*/
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#define WRITER_DELAY_MS 10
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#define READER_DELAY_MS 20
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#define WRITER_STACK_SIZE 4096
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#define READER_STACK_SIZE 4096
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#define WRITER_PRIORITY (NORMALPRIO + 1)
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#define READER_PRIORITY (NORMALPRIO + 2)
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static thread_t *writertp;
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static thread_t *readertp;
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static tribuf_t tribuf;
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static char buffers[3];
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static const char text[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ\r\n";
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/*
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* Reads from the front buffer.
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*/
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static char read_front(void) {
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const char *front;
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msg_t error;
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/* Wait until a new front buffer gets available with prepared data */
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error = tribufWaitReadyTimeout(&tribuf, TIME_MS2I(1000));
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if (error == MSG_TIMEOUT)
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chSysHalt("ERROR: read_front() timed out");
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/* Retrieve the new front buffer */
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tribufSwapFront(&tribuf);
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front = (const char *)tribufGetFront(&tribuf);
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/* Read data from the new front buffer */
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return front[0];
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}
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/*
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* Overwrites the back buffer with the provided character.
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*/
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static void write_back(char c) {
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char *back;
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/* Retrieve the current back buffer */
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back = (char *)tribufGetBack(&tribuf);
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/* Prepare data onto the current back buffer */
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back[0] = c;
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/* Exchange the prepared buffer with a new one */
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tribufSwapBack(&tribuf);
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}
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/*
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* Overwrites the back buffer with a fixed text, character by character.
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*/
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static THD_WORKING_AREA(writer_wa, WRITER_STACK_SIZE);
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static THD_FUNCTION(writer_thread, arg) {
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const uint32_t delay = (uint32_t)(msg_t)arg;
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size_t i;
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char c;
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chRegSetThreadName("writer_thread");
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for (;;) {
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for (i = 0; i < sizeof(text); ++i) {
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c = text[i];
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write_back(c);
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chThdSleepMilliseconds(delay);
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}
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}
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}
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/*
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* Reads the front buffer and prints it.
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*/
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static THD_WORKING_AREA(reader_wa, READER_STACK_SIZE);
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static THD_FUNCTION(reader_thread, arg) {
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const uint32_t delay = (uint32_t)(msg_t)arg;
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char c;
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chRegSetThreadName("reader_thread");
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for (;;) {
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c = read_front();
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fprintf(stdout, "%c", c);
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chThdSleepMilliseconds(delay);
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}
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}
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/*===========================================================================*/
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/* Initialization and main thread. */
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/*===========================================================================*/
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/*
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* Simulator main.
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*/
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int main(void) {
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/*
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* System initializations.
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* - HAL initialization, this also initializes the configured device drivers
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* and performs the board-specific initializations.
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* - Kernel initialization, the main() function becomes a thread and the
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* RTOS is active.
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*/
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halInit();
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chSysInit();
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/*
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* Writer and reader threads started for triple buffer demo.
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*/
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tribufObjectInit(&tribuf, &buffers[0], &buffers[1], &buffers[2]);
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readertp = chThdCreateStatic(reader_wa, sizeof(reader_wa),
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READER_PRIORITY,
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reader_thread, (void *)READER_DELAY_MS);
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writertp = chThdCreateStatic(writer_wa, sizeof(writer_wa),
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WRITER_PRIORITY,
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writer_thread, (void *)WRITER_DELAY_MS);
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/*
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* Let the threads process data.
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*/
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for (;;)
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chThdSleepMilliseconds(1000);
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return 0;
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}
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/*
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* Critical error function.
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*/
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void halt(const char *reason) {
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fflush(stdout);
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fputs("\n", stdout);
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fputs(reason, stderr);
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fflush(stderr);
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exit(1);
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}
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