added decoder_read()

On our way to stabilize the decoder API, we will one day remove the
input stream functions.  The most basic function, read() will be
provided by decoder_api.h with this patch.  It already contains a loop
(still with manual polling), error/eof handling and decoder command
checks.  This kind of code used to be duplicated in all decoder
plugins.

src/decoder_api.c

@@ -89,6 +89,30 @@ void decoder_seek_error(struct decoder * decoder)
 	decoder_command_finished(decoder);
 }
 
+size_t decoder_read(struct decoder *decoder,
+		    InputStream *inStream,
+		    void *buffer, size_t length)
+{
+	size_t nbytes;
+
+	assert(inStream != NULL);
+	assert(buffer != NULL);
+
+	while (1) {
+		/* XXX don't allow decoder==NULL */
+		if (decoder != NULL && dc.command != DECODE_COMMAND_NONE)
+			return 0;
+
+		nbytes = readFromInputStream(inStream, buffer, 1, length);
+		if (nbytes > 0 || inputStreamAtEOF(inStream))
+			return nbytes;
+
+		/* sleep for a fraction of a second! */
+		/* XXX don't sleep, wait for an event instead */
+		my_usleep(10000);
+	}
+}
+
 /**
  * All chunks are full of decoded data; wait for the player to free
  * one.

src/decoder_api.h

@@ -121,6 +121,15 @@ double decoder_seek_where(struct decoder * decoder);
 
 void decoder_seek_error(struct decoder * decoder);
 
+/**
+ * Blocking read from the input stream.  Returns the number of bytes
+ * read, or 0 if one of the following occurs: end of file; error;
+ * command (like SEEK or STOP).
+ */
+size_t decoder_read(struct decoder *decoder,
+		    InputStream *inStream,
+		    void *buffer, size_t length);
+
 /**
  * This function is called by the decoder plugin when it has
  * successfully decoded block of input data.

src/inputPlugins/_ogg_common.c

@@ -37,15 +37,7 @@ ogg_stream_type ogg_stream_type_detect(InputStream * inStream)
 
 	seekInputStream(inStream, 0, SEEK_SET);
 
-	while (1) {
-		r = readFromInputStream(inStream, buf, 1, sizeof(buf));
-		if (inStream->error)
-			break;
-		if (!r && !inputStreamAtEOF(inStream))
-			my_usleep(10000);
-		else
-			break;
-	}
+	r = decoder_read(NULL, inStream, buf, sizeof(buf));
 
 	if (r > 0)
 		seekInputStream(inStream, 0, SEEK_SET);

src/inputPlugins/aac_plugin.c

@@ -65,11 +65,9 @@ static void fillAacBuffer(AacBuffer * b)
 		size_t rest = FAAD_MIN_STREAMSIZE * AAC_MAX_CHANNELS -
 			b->bytesIntoBuffer;
 
-		bread = readFromInputStream(b->inStream,
-					    (void *)(b->buffer +
-						     b->
-						     bytesIntoBuffer),
-					    1, rest);
+		bread = decoder_read(b->decoder, b->inStream,
+				     (void *)(b->buffer + b->bytesIntoBuffer),
+				     rest);
 		if (bread == 0 && inputStreamAtEOF(b->inStream))
 			b->atEof = 1;
 		b->bytesIntoBuffer += bread;

src/inputPlugins/flac_plugin.c

@@ -33,14 +33,7 @@ static flac_read_status flacRead(mpd_unused const flac_decoder * flacDec,
 	FlacData *data = (FlacData *) fdata;
 	size_t r;
 
-	while (1) {
-		r = readFromInputStream(data->inStream, (void *)buf, 1, *bytes);
-		if (r == 0 && !inputStreamAtEOF(data->inStream) &&
-		    decoder_get_command(data->decoder) != DECODE_COMMAND_STOP)
-			my_usleep(10000);
-		else
-			break;
-	}
+	r = decoder_read(data->decoder, data->inStream, (void *)buf, *bytes);
 	*bytes = r;
 
 	if (r == 0 && decoder_get_command(data->decoder) != DECODE_COMMAND_STOP) {

src/inputPlugins/mp3_plugin.c

@@ -233,15 +233,10 @@ static int fillMp3InputBuffer(mp3DecodeData * data)
 	if (readSize == 0)
 		return -1;
 
-	readed = readFromInputStream(data->inStream, readStart, (size_t) 1,
-				     readSize);
-	if (readed <= 0 && inputStreamAtEOF(data->inStream))
+	readed = decoder_read(data->decoder, data->inStream,
+			      readStart, readSize);
+	if (readed == 0)
 		return -1;
-	/* sleep for a fraction of a second! */
-	else if (readed <= 0) {
-		readed = 0;
-		my_usleep(10000);
-	}
 
 	mad_stream_buffer(&data->stream, data->readBuffer, readed + remaining);
 	(data->stream).error = 0;
@@ -324,13 +319,10 @@ static void mp3_parseId3Tag(mp3DecodeData * data, size_t tagsize,
 		while (count < tagsize) {
 			size_t len;
 
-			len = readFromInputStream(data->inStream,
-						  allocated + count, (size_t) 1,
-						  tagsize - count);
-			if (len <= 0 && inputStreamAtEOF(data->inStream)) {
+			len = decoder_read(data->decoder, data->inStream,
+					   allocated + count, tagsize - count);
+			if (len == 0)
 				break;
-			} else if (len <= 0)
-				my_usleep(10000);
 			else
 				count += len;
 		}

src/inputPlugins/mpc_plugin.c

@@ -32,20 +32,9 @@ typedef struct _MpcCallbackData {
 
 static mpc_int32_t mpc_read_cb(void *vdata, void *ptr, mpc_int32_t size)
 {
-	mpc_int32_t ret = 0;
 	MpcCallbackData *data = (MpcCallbackData *) vdata;
 
-	while (1) {
-		ret = readFromInputStream(data->inStream, ptr, 1, size);
-		if (ret == 0 && !inputStreamAtEOF(data->inStream) &&
-		    (data->decoder &&
-		     decoder_get_command(data->decoder) != DECODE_COMMAND_STOP))
-			my_usleep(10000);
-		else
-			break;
-	}
-
-	return ret;
+	return decoder_read(data->decoder, data->inStream, ptr, size);
 }
 
 static mpc_bool_t mpc_seek_cb(void *vdata, mpc_int32_t offset)

src/inputPlugins/oggflac_plugin.c

@@ -47,14 +47,7 @@ static OggFLAC__SeekableStreamDecoderReadStatus of_read_cb(const
 	FlacData *data = (FlacData *) fdata;
 	size_t r;
 
-	while (1) {
-		r = readFromInputStream(data->inStream, (void *)buf, 1, *bytes);
-		if (r == 0 && !inputStreamAtEOF(data->inStream) &&
-		    decoder_get_command(data->decoder) != DECODE_COMMAND_STOP)
-			my_usleep(10000);
-		else
-			break;
-	}
+	r = decoder_read(data->decoder, data->inStream, (void *)buf, *bytes);
 	*bytes = r;
 
 	if (r == 0 && !inputStreamAtEOF(data->inStream) &&

src/inputPlugins/oggvorbis_plugin.c

@@ -58,18 +58,12 @@ static size_t ogg_read_cb(void *ptr, size_t size, size_t nmemb, void *vdata)
 	size_t ret;
 	OggCallbackData *data = (OggCallbackData *) vdata;
 
-	while (1) {
-		ret = readFromInputStream(data->inStream, ptr, size, nmemb);
-		if (ret == 0 && !inputStreamAtEOF(data->inStream) &&
-		    decoder_get_command(data->decoder) != DECODE_COMMAND_STOP) {
-			my_usleep(10000);
-		} else
-			break;
-	}
+	ret = decoder_read(data->decoder, data->inStream, ptr, size * nmemb);
+
 	errno = 0;
 	/*if(ret<0) errno = ((InputStream *)inStream)->error; */
 
-	return ret;
+	return ret / size;
 }
 
 static int ogg_seek_cb(void *vdata, ogg_int64_t offset, int whence)

src/inputPlugins/wavpack_plugin.c

@@ -358,7 +358,7 @@ static int32_t read_bytes(void *id, void *data, int32_t bcount)
 		--bcount;
 		++i;
 	}
-	return i + readFromInputStream(isp->is, buf, 1, bcount);
+	return i + decoder_read(isp->decoder, isp->is, buf, bcount);
 }
 
 static uint32_t get_pos(void *id)