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main.c
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main.c
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#include <stdio.h>
#include "playlist.h"
#include <stdlib.h>
typedef struct mysongT {
song tune;
int played;
} mysong;
struct playlistType{
int first, last;
mysong * Q;
int size, next, mode;
};
int initSize = 10;
/* EFFECTS: allocates and initialises an empty playlist which will play in normal mode.*/
playlist initialisePlaylist() {
playlist p = malloc(sizeof(playlist));
p->first = -1;
p->last = -1;
p->Q = malloc(sizeof(mysong) * initSize);
p->size = initSize;
p->next = 0;
p->mode = 0;
return p;
}
//EFFECTS: copies array aux into array Q
void copy(mysong * aux, mysong * Q, int size) {
int i;
for (i=0; i<size; i++) {
Q[i] = aux[i];
}
}
// EFFECTS: checks whether arrray p->Q needs expanding
void check(playlist p) {
if (p->last == p->size - 1) {
mysong * aux = p->Q;
p->size = p->size * 2;
p->Q = malloc(sizeof(mysong) * p->size);
copy(aux, p->Q, p->size);
//free(aux);
}
}
/* EFFECTS: returns position of next song to be played */
int findnext(playlist p) {
if (p->next == p->last)
p->next = 0;
else
p->next++;
return p->next;
}
/* EFFECTS: adds s as the last element of p.*/
void addSong(playlist p, song s){
check (p);
mysong newsong;
newsong.tune = s;
newsong.played = 0;
p->last++;
p->Q[p->last] = newsong;
}
/* EFFECTS: returns the ID of the next song of p to be played.*/
int playSong(playlist p) {
int aux;
aux = p->next;
if (p->mode == 1) {
if (p->Q[p->next].played == 0) { //unplayed
p->Q[p->next].played = 1;
p->next = findnext(p);
return p->Q[aux].tune->id;
}
else { // already played
int r;
int i;
p->next = findnext(p);
while (i <= p->last) {
if (p->Q[p->next].played == 0) {
r = p->Q[p->next].tune->id;
p->Q[p->next].played = 1;
p->next = findnext(p);
break;
}
else {
r = -1;
p->next = findnext(p);
}
i++;
}
return r;
}
}
else { // p->mode == 0
p->Q[p->next].played = 1;
p->next = findnext(p);
return p->Q[aux].tune->id;
}
}
/* EFFECTS: set p to play from the ith song. I.e., after the call the ith song will be the next song to be played.*/
void playFrom(playlist p, int i){
if (i-1 <= p->last)
p->next = i - 1;
}
/* EFFECTS: if p is not empty, skips the next song which will not be played.*/
void skipSong(playlist p) {
if (p)
p->next = findnext(p);
}
/* EFFECTS: if mode is 1 (skip Mode) then set the playlist p to play only songs that were not played before.
* If mode is 0 (normal mode) resets p and sets it to play all songs.*/
void skipAllPlayedSongs(playlist p, int mode){
if (mode == 1) {
p->mode = 1;
}
else {
p->mode = 0;
int i = 0;
p->next = 0;
for (i=0; i<=p->last; i++)
p->Q[i].played = 0;
}
}
/* EFFECTS: resets p making the first song in the sequence to be played the next to be played.*/
void restart(playlist p){
p->next = 0;
}
/* EFFECTS: if i and j are smaller than or equal to the number of songs in p,
* the function swaps the ith song and the jth song in p.*/
void swapSongs(playlist p, int i, int j){
int a = i-1;
int b = j-1;
if (a <= p->last && b <= p->last) {
mysong aux;
aux = p->Q[a];
p->Q[a] = p->Q[b];
p->Q[b] = aux;
}
}
/* EFFECTS: deallocate all the memory required by p.*/
void freePlaylist(playlist p){
free(p);
}