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/*
* parser.c
* Handles parsing of songs and playing of the parsed notes
*
* Created on: Nov 25, 2025
* Author: sowgro
*/
#include <parser.h>
#include "endian_converters.h"
#include <stdint.h>
#include "endian_converters.h"
#include "hw8.h"
#include "activity4.h"
#include "systick.h"
#include "tone.h"
static track_t tracks[4];
static int nTracks;
static int startTime;
static song_info_t song_info;
static uint16_t division;
/**
* Prepare the parser to play the notes
* Expected that parse_song() was called first
*/
void parser_play_init() {
DAC_Init();
DAC_Start();
startTime = systick_get_count();
}
uint32_t ticks_to_ms(uint32_t ticks) {
// tempo is in microseconds per quarter note
uint32_t us_per_tick = song_info.tempo / division;
return (ticks * us_per_tick);
}
/**
* Play any notes that are ready to be played
* Should be called continuously in the play state
* Expected that parse_song() was called first
*/
void parser_play_loop() {
int curAbsTime = systick_get_count() - startTime;
for (int i = 1; i < 2; i++) {
if (tracks[i].curEventIndex >= tracks[i].nEvents) {
continue;
}
note_event_t curEvent = tracks[i].events[tracks[i].curEventIndex];
if (ticks_to_ms(curEvent.abs_time) <= curAbsTime) {
switch (curEvent.ev_type) {
case NOTE_OFF_EVENT:
remove_tone(curEvent.key_number); break;
case NOTE_ON_EVENT:
add_tone(curEvent.key_number, curEvent.value); break;
}
tracks[i].curEventIndex++;
}
}
play_tones();
}
/**
* Parse a song and populate the static fields with its information
* @param p_song a pointer to the current position in the song
*/
void parse_song(uint8_t *p_song) {
header_t header;
header = get_header(p_song);
p_song += sizeof(header_t) - 2; // move pointer past header
parse_song_info(p_song, &song_info);
division = header.division;
nTracks = header.ntrcks;
for(int i = 0; i < nTracks; i++){
p_song = parse_track(p_song, &tracks[i]);
}
}
/**
* Parse the track and populate the track parameter with its information
* @param p_song a pointer to the current position in the song
* @param track a pointer to a track to output to
* @returns a pointer to the song after the track
*/
uint8_t *parse_track(uint8_t *p_song, track_t *track) {
p_song += 4; // skip MTrk
uint32_t MTrk_len = convert_to_uint32(p_song);
p_song += 4;
int curEvent = 0;
uint32_t prev_abs_time = 0;
for (uint8_t *p_end = p_song + MTrk_len; p_song != p_end; ) {
note_event_t note;
parseDelay_result_t delay_result = parseDelay(p_song);
p_song += delay_result.bytes_used;
if (*p_song >> 4 == 0b1000) {
note.ev_type = NOTE_OFF_EVENT;
} else if (*p_song >> 4 == 0b1001) {
note.ev_type = NOTE_ON_EVENT;
} else if (*p_song >> 4 == 0b1010) {
note.ev_type = KEY_PRESSURE;
} else {
continue;
}
uint32_t abs_time = prev_abs_time + delay_result.value;
note.abs_time = abs_time;
prev_abs_time = abs_time;
// size_t channelNumber = *p_song && 0b00001111;
p_song++;
note.key_number = *p_song;
p_song++;
note.value = *p_song;
p_song++;
track->events[curEvent++] = note;
}
track->nEvents = curEvent;
track->curEventIndex = 0;
return p_song;
}
/**
* Parses the track information
* @param p_song a pointer to the current position in the song
* @param ret the output parameter
* @returns a pointer to the song after the track info
*/
uint8_t *parse_song_info(uint8_t *p_song, song_info_t *ret) {
ret->copyright = 0;
ret->tempo = 0;
ret->title = 0;
p_song += 4; // move past MTrk label
uint32_t MTrk_len = convert_to_uint32(p_song); // read in size of MTrk
p_song += sizeof(MTrk_len);
for (uint8_t *p_end = p_song + MTrk_len; p_song != p_end; p_song++) {
// FF 02 - copyright
if (convert_to_uint16(p_song) == 0xFF02) {
p_song += sizeof(uint16_t);
uint8_t ev_len = *(uint8_t *) p_song;
p_song += sizeof(ev_len);
ret->copyright = (char *) p_song;
ret->copyright[ev_len] = 0;
}
// FF 03 - title
if (convert_to_uint16(p_song) == 0xFF03) {
p_song += sizeof(uint16_t);
uint8_t ev_len = *(uint8_t *) p_song;
p_song += sizeof(ev_len);
ret->title = (char *) p_song;
ret->title[ev_len] = 0;
}
// FF 51 - tempo
if (convert_to_uint16(p_song) == 0xFF51) {
p_song += sizeof(uint16_t);
p_song += sizeof(uint8_t); // skip length, always 03
ret->tempo = convert_to_uint24(p_song);
}
}
return p_song;
}
/**
* An accessor for other files to get the song information
*/
song_info_t parser_get_song_info() {
return song_info;
}
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