Read default volume from device settings at start (#987)

libs/music/docs/reference/music.md

@@ -12,4 +12,5 @@ music.setTempo(120)
 music.noteFrequency(Note.C)
 music.beat()
 music.setVolume(50)
-```
+music.volume()
+```

libs/music/music.cpp

@@ -13,7 +13,22 @@
 
 namespace music {
 
-uint8_t currVolume = 50;
+int _readSystemVolume() {
+    char ParBuf[8];
+    int volume;
+
+    int fd = open("../sys/settings/Volume.rtf", O_RDONLY);
+    read(fd, ParBuf, sizeof(ParBuf));
+    close(fd);
+    if (sscanf(ParBuf,"%d",&volume) > 0) {
+        if ((volume >= 0) && (volume <= 100)) {
+            return volume;
+        }
+    }
+    return 50;
+}
+
+uint8_t currVolume = _readSystemVolume();
 uint8_t *lmsSoundMMap;
 
 int writeDev(void *data, int size) {
@@ -37,6 +52,18 @@ void setVolume(int volume) {
     currVolume = max(0, min(100, volume));
 }
 
+/**
+* Return the output volume of the sound synthesizer.
+*/
+//% weight=96
+//% blockId=synth_get_volume block="volume"
+//% parts="speaker" blockGap=8
+//% help=music/volume
+//% weight=1
+int volume() {
+    return currVolume;
+}
+
 #define SOUND_CMD_BREAK 0
 #define SOUND_CMD_TONE 1
 #define SOUND_CMD_PLAY 2
@@ -218,4 +245,4 @@ Buffer buffer(Sound snd) {
 void play(Sound snd) {
     music::playSample(snd);
 }
-}
+}

libs/music/shims.d.ts

@@ -13,6 +13,16 @@ declare namespace music {
     //% weight=1 shim=music::setVolume
     function setVolume(volume: int32): void;
 
+    /**
+     * Return the output volume of the sound synthesizer.
+     */
+    //% weight=96
+    //% blockId=synth_get_volume block="volume"
+    //% parts="speaker" blockGap=8
+    //% help=music/volume
+    //% weight=1 shim=music::volume
+    function volume(): int32;
+
     /**
      * Play a tone through the speaker for some amount of time.
      * @param frequency pitch of the tone to play in Hertz (Hz), eg: Note.C

libs/music/test.ts

@@ -5,3 +5,4 @@ music.playTone(1440, 500)
 pause(500)
 music.playTone(2440, 500)
 pause(500)
+music.volume()