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//Leif Messingerconst int BUZZER_PIN = 8;const int BUTTON_PIN = 2;const int BUTTON_PINMODE = INPUT_PULLUP;#define DEBOUNCE_DELAY 50class Button{private:short buttonPin;bool buttonState;bool lastButtonState;int lastDebounceTime;public:Button(short buttonPin): buttonState(HIGH), lastButtonState(LOW), lastDebounceTime(millis()){this->buttonPin = buttonPin;}bool checkForPress(const bool desiredState){ //Returns true if button pressedbool reading = (bool)digitalRead(buttonPin);// check to see if you just pressed the button// (i.e. the input went from LOW to HIGH), and you've waited long enough// since the last press to ignore any noise:// If the switch changed, due to noise or pressing:if (reading != lastButtonState) {// reset the debouncing timerlastDebounceTime = millis();}else if ((millis() - lastDebounceTime) > DEBOUNCE_DELAY) {// whatever the reading is at, it's been there for longer than the debounce// delay, so take it as the actual current state:// if the button state has changed:if (reading != buttonState) {buttonState = reading;// only toggle the LED if the new button state is HIGHif (buttonState == desiredState) {return true;}}}// save the reading. Next time through the loop, it'll be the lastButtonState:lastButtonState = reading;return false;}void waitForPress(const bool desiredState){while(!checkForPress(desiredState));}};class Note{public:short frequency; //Short max is ~ 30k, so way higher than you can hearshort lag; //Also 30k ms is 30 secondsfloat sustainPercentage;};const short normalBeatLength = 500;const short wholeNote = 4*normalBeatLength;const short halfNote = 2*normalBeatLength;const short dottedQuarterNote = normalBeatLength + (normalBeatLength / 2);const short quarterNote = normalBeatLength;const short dottedEighthNote = ((3 * normalBeatLength) / 4);const short eighthNote = normalBeatLength/ 2;const short sixteenthNote = normalBeatLength / 4;const float normalSustainLength = .25;void beep(const Note& note){ //It might go terribly wrong if you try to beep two tones at the same time.tone(BUZZER_PIN, note.frequency);delay(note.lag * note.sustainPercentage);noTone(BUZZER_PIN);delay(note.lag * (1.0 - note.sustainPercentage));}Note song[] = {{(int)523.25, halfNote, normalSustainLength},{(int)392, eighthNote, normalSustainLength},{(int)523.25, quarterNote, normalSustainLength},{(int)392, dottedEighthNote, normalSustainLength},{(int)440.00, sixteenthNote, normalSustainLength},{(int)493.88, quarterNote, normalSustainLength},{(int)329.63, eighthNote, normalSustainLength},{(int)329.63, eighthNote, normalSustainLength},{(int)440.00, quarterNote, normalSustainLength},{(int)392, dottedEighthNote, normalSustainLength},{(int)349.23, sixteenthNote, normalSustainLength},{(int)392, quarterNote, normalSustainLength},{(int)261.63, dottedEighthNote, normalSustainLength},{(int)261.63, sixteenthNote, normalSustainLength},{(int)293.66, quarterNote, normalSustainLength},{(int)293.66, dottedEighthNote, normalSustainLength},{(int)329.63, sixteenthNote, normalSustainLength},{(int)349.23, quarterNote, normalSustainLength},{(int)349.23, dottedEighthNote, normalSustainLength},{(int)392.00, sixteenthNote, normalSustainLength},{(int)440.00, quarterNote, normalSustainLength},{(int)493.88, eighthNote, normalSustainLength},{(int)523.25, eighthNote, normalSustainLength},{(int)587.33, dottedQuarterNote, normalSustainLength},{(int)392, eighthNote, normalSustainLength},{(int)659.25, quarterNote, normalSustainLength},{(int)587.33, dottedEighthNote, normalSustainLength},{(int)523.25, sixteenthNote, normalSustainLength},{(int)587.33, quarterNote, normalSustainLength},{(int)493.88, eighthNote, normalSustainLength},{(int)392, eighthNote, normalSustainLength},{(int)523.25, quarterNote, normalSustainLength},{(int)493.88, dottedEighthNote, normalSustainLength},{(int)440.00, sixteenthNote, normalSustainLength},{(int)493.88, quarterNote, normalSustainLength},{(int)329.63, eighthNote, normalSustainLength},{(int)329.63, eighthNote, normalSustainLength},{(int)440.00, quarterNote, normalSustainLength},{(int)392, dottedEighthNote, normalSustainLength},{(int)349.23, sixteenthNote, normalSustainLength},{(int)392, quarterNote, normalSustainLength},{(int)261.63, dottedEighthNote, normalSustainLength},{(int)261.63, sixteenthNote, normalSustainLength},{(int)523.25, quarterNote, normalSustainLength},{(int)493.88, dottedEighthNote, normalSustainLength},{(int)440.00, sixteenthNote, normalSustainLength},{(int)392.00, halfNote, normalSustainLength * .5},};size_t songLength = (sizeof(song) / sizeof(Note));void playSong(){for(size_t pos = 0; pos < songLength; ++pos){const Note& bruh = song[pos];beep(bruh);}}void setup() {const int BUZZER_PIN = 8;pinMode(BUZZER_PIN, OUTPUT);pinMode(BUTTON_PIN, BUTTON_PINMODE);playSong();}Button button(BUTTON_PIN);void loop() {button.waitForPress(LOW);// read the state of the switch into a local variable:playSong();}
// Client side implementation of UDP client-server model#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <string.h>#include <sys/types.h>#include <sys/socket.h>#include <arpa/inet.h>#include <netinet/in.h>#define PORT 8008#define MAXLINE 1024// Driver codeint main() {char buffer[MAXLINE];struct sockaddr_in servaddr;// Creating socket file descriptorint sockfd = socket(AF_INET, SOCK_DGRAM, 0);if ( sockfd < 0 ) {perror("socket creation failed");exit(EXIT_FAILURE);}struct timeval timeout;timeout.tv_sec = 1; //Wait 1 secondtimeout.tv_usec = 0;if (setsockopt (sockfd, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof timeout) < 0) perror("setsockopt failed\n");if (setsockopt (sockfd, SOL_SOCKET, SO_SNDTIMEO, &timeout, sizeof timeout) < 0) perror("setsockopt failed\n");memset(&servaddr, 0, sizeof(servaddr));// Filling server informationservaddr.sin_family = AF_INET;servaddr.sin_port = htons(PORT);servaddr.sin_addr.s_addr = inet_addr("192.168.4.65");for(int i = 0; i < 10; ++i){char* message = "PING";int sendStatus = sendto(sockfd, (const char *)message, strlen(message), MSG_CONFIRM, (const struct sockaddr *) &servaddr, sizeof(servaddr));if(sendStatus >= 0){printf("Sent PING\n");}else{printf("Send failed\n");continue;}int len = sizeof(struct sockaddr_in);int bytesRecieved = recvfrom(sockfd, (char *)buffer, MAXLINE, MSG_WAITALL, (struct sockaddr *) &servaddr, &len); //We can reuse servaddr because the port the server sends messages from is the same one we send toif(bytesRecieved >= 0){buffer[bytesRecieved] = '\0';printf("Recieved %s\n", buffer);}else{printf("Recieved nothing: Packet Dropped\n", buffer);}}close(sockfd);return 0;}
#include <stdio.h>#include <string.h>#include <unistd.h>#define READ 0 /* The index of the read end of the pipe */#define WRITE 1 /* The index of the write end of the pipe */char * phrase = "This goes in the pipe";int main() {int fd[2], bytesRead;char message[100]; /* Parent process' message buffer */pipe(fd); /* Create unnamed pipe */if (fork() == 0) /* Child, writer */ {close(fd[READ]); /* Close unused end */write(fd[WRITE], phrase, strlen(phrase) + 1); /* Include NULL */close(fd[WRITE]); /* Close used end */} else /* Parent, reader */ {close(fd[WRITE]); /* Close unused end */bytesRead = read(fd[READ], message, 100);printf("Parent just read %i bytes: %s\n", bytesRead, message);close(fd[READ]); /* Close used end */}}
#include <stdio.h>#include <stdlib.h>// give an array of identical coins (ints), represented by 1's and one 2// we can find the heavy coin (2) by summing the contents of the thirdsint sum_subarr(int arr[], int l, int r){int sum = 0;for(int i = l; i <= r; i++){sum += arr[i];}return sum;}int heavy_coin(int arr[], int l, int r){if(r == l){return r;}int midl = l + (r - l)/3;int midr = r - (r - l)/3;int lw = sum_subarr(arr, l, midl);int mw = sum_subarr(arr, midl + 1, midr);if ( lw > mw ){return heavy_coin(arr, l, midl);}else if ( lw < mw ){return heavy_coin(arr, midl + 1, midr);}else{return heavy_coin(arr, midr + 1, r);}}int main(int argc, char *argv[]){int arr[] = {1,1,1,1,2,1,1,1,1};int l = 0;int r = 8;int res = -1;res = heavy_coin(arr, l, r);printf("Hevy coin is at index: %d\n", res);return EXIT_SUCCESS;}
#include <stdio.h>#include <assert.h>#include <signal.h>void myHandler(int iSig) {printf("In myHandler with argument %d\n", iSig);}int main() {void( * pfRet)(int) = signal(SIGINT, myHandler);assert(pfRet != SIG_ERR);printf("Entering an infinite loop\n");while (1) {printf(".");}return 0; // use CTRL+\ to exit}
#include <stdio.h>#include <sys/types.h>#include <unistd.h>int main() {pid_t pid; /* could be int */int i;pid = fork();printf("PID=%d\n", pid);if (pid > 0) {/* parent */for (i = 0; i < 10; i++)printf("\t\t\tPARENT %d\n", i);} else {/* child */for (i = 0; i < 10; i++)printf("CHILD %d\n", i);}return 0;}