led-player.zip_Linux led_led-player.c_player

#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/ioctl.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <sys/select.h> #include <sys/time.h> #include <string.h> static int led_fd; static int type = 1; static void push_leds(void) { static unsigned step; unsigned led_bitmap; int i; switch(type) { case 0: if (step >= 6) { step = 0; } if (step < 3) { led_bitmap = 1 << step; } else { led_bitmap = 1 << (6 - step); } break; case 1: if (step > 255) { step = 0; } led_bitmap = step; break; default: led_bitmap = 0; } step++; for (i = 0; i < 4; i++) { ioctl(led_fd, led_bitmap & 1, i); led_bitmap >>= 1; } } int main(void) { int led_control_pipe; int null_writer_fd; // for read endpoint not blocking when control process exit double period = 0.5; led_fd = open("/dev/leds0", 0); if (led_fd < 0) { led_fd = open("/dev/leds", 0); } if (led_fd < 0) { perror("open device leds"); exit(1); } unlink("/tmp/led-control"); mkfifo("/tmp/led-control", 0666); led_control_pipe = open("/tmp/led-control", O_RDONLY | O_NONBLOCK); if (led_control_pipe < 0) { perror("open control pipe for read"); exit(1); } null_writer_fd = open("/tmp/led-control", O_WRONLY | O_NONBLOCK); if (null_writer_fd < 0) { perror("open control pipe for write"); exit(1); } for (;;) { fd_set rds; struct timeval step; int ret; FD_ZERO(&rds); FD_SET(led_control_pipe, &rds); step.tv_sec = period; step.tv_usec = (period - step.tv_sec) * 1000000L; ret = select(led_control_pipe + 1, &rds, NULL, NULL, &step); if (ret < 0) { perror("select"); exit(1); } if (ret == 0) { push_leds(); } else if (FD_ISSET(led_control_pipe, &rds)) { static char buffer[200]; for (;;) { char c; int len = strlen(buffer); if (len >= sizeof buffer - 1) { memset(buffer, 0, sizeof buffer); break; } if (read(led_control_pipe, &c, 1) != 1) { break; } if (c == '\r') { continue; } if (c == '\n') { int tmp_type; double tmp_period; if (sscanf(buffer,"%d%lf", &tmp_type, &tmp_period) == 2) { type = tmp_type; period = tmp_period; } fprintf(stderr, "type is %d, period is %lf\n", type, period); memset(buffer, 0, sizeof buffer); break; } buffer[len] = c; } } } close(led_fd); return 0; }