audio/mp3: Remove g_error

audio/mp3/decode_notjs.go

@@ -20,7 +20,6 @@ package mp3
 import "C"
 
 import (
-	"errors"
 	"io"
 	"unsafe"
 )
@@ -88,8 +87,6 @@ func writeToWriter(data unsafe.Pointer, size C.int) C.size_t {
 	return C.size_t(n)
 }
 
-var g_error error
-
 func decode(r io.Reader, w io.Writer) error {
 	reader = r
 	writer = w
@@ -102,10 +99,7 @@ func decode(r io.Reader, w io.Writer) error {
 		if Get_Filepos() == eof {
 			break
 		}
-		if err != nil {
-			return err
-		}
-		return errors.New("mp3: not enough maindata to decode frame")
+		return err
 	}
-	return g_error
+	return nil
 }

audio/mp3/maindata.go

@@ -175,7 +175,7 @@ var theMainDataBytes mainDataBytes
 
 func getMainData(size int, begin int) error {
 	if size > 1500 {
-		g_error = fmt.Errorf("size = %d", size)
+		return fmt.Errorf("mp3: size = %d", size)
 	}
 	// Check that there's data available from previous frames if needed
 	if int(begin) > theMainDataBytes.top {
@@ -202,7 +202,8 @@ func getMainData(size int, begin int) error {
 		theMainDataBytes.pos = 0
 		theMainDataBytes.idx = 0
 		theMainDataBytes.top += size
-		return fmt.Errorf("mp3: not enought frame data; read next frame?")
+		// TODO: Define a special error and enable to continue the next frame.
+		return fmt.Errorf("mp3: frame can't be decoded")
 	}
 	/* Copy data from previous frames */
 	for i := 0; i < begin; i++ {

audio/mp3/read.go

@@ -53,23 +53,26 @@ func readFrame() error {
 	if err := readHeader(); err != nil {
 		return err
 	}
-	/* Get CRC word if present */
+	// Get CRC word if present
 	if C.g_frame_header.protection_bit == 0 {
 		if err := readCRC(); err != nil {
 			return err
 		}
 	}
-	if C.g_frame_header.layer == 3 { /* Get audio data */
-		Read_Audio_L3() /* Get side info */
-		/* If there's not enough main data in the bit reservoir,
-		 * signal to calling function so that decoding isn't done! */
-		/* Get main data(scalefactors and Huffman coded frequency data) */
-		if err := readMainL3(); err != nil {
-			return err
-		}
-	} else {
+
+	if C.g_frame_header.layer != 3 {
 		return fmt.Errorf("mp3: Only layer 3(!= %d) is supported!", C.g_frame_header.layer)
 	}
+	// Get side info
+	if err := readAudioL3(); err != nil {
+		return err
+	}
+	// If there's not enough main data in the bit reservoir,
+	// signal to calling function so that decoding isn't done!
+	// Get main data(scalefactors and Huffman coded frequency data)
+	if err := readMainL3(); err != nil {
+		return err
+	}
 	return nil
 }
 

audio/mp3/sideinfo.go

@@ -44,8 +44,7 @@ var g_mpeg1_bitrates = [3][15]int{
 
 var g_sampling_frequency = [3]int{44100, 48000, 32000}
 
-//export Read_Audio_L3
-func Read_Audio_L3() C.int {
+func readAudioL3() error {
 	nch := 2
 	if C.g_frame_header.mode == C.mpeg1_mode_single_channel {
 		nch = 1
@@ -56,8 +55,7 @@ func Read_Audio_L3() C.int {
 		g_sampling_frequency[C.g_frame_header.sampling_frequency] +
 		int(C.g_frame_header.padding_bit)
 	if framesize > 2000 {
-		g_error = fmt.Errorf("mp3: framesize = %d\n", framesize)
-		return C.ERROR
+		return fmt.Errorf("mp3: framesize = %d\n", framesize)
 	}
 	/* Sideinfo is 17 bytes for one channel and 32 bytes for two */
 	sideinfo_size := 32
@@ -71,9 +69,8 @@ func Read_Audio_L3() C.int {
 		main_data_size -= 2
 	}
 	/* Read sideinfo from bitstream into buffer used by getSideBits() */
-	getSideinfo(sideinfo_size)
-	if Get_Filepos() == eof {
-		return C.ERROR
+	if err := getSideinfo(sideinfo_size); err != nil {
+		return err
 	}
 	/* Parse audio data */
 	/* Pointer to where we should start reading main data */
@@ -127,7 +124,7 @@ func Read_Audio_L3() C.int {
 			C.g_side_info.count1table_select[gr][ch] = C.uint(getSideBits(1))
 		}
 	}
-	return C.OK
+	return nil
 }
 
 // A sideInfo is a bit reservoir for side info
@@ -138,16 +135,25 @@ type sideInfo struct {
 
 var theSideInfo sideInfo
 
-func getSideinfo(size int) {
+func getSideinfo(size int) error {
 	buf := make([]int, size)
-	n, err := getBytes(buf)
-	if err != nil && err != io.EOF {
-		g_error = fmt.Errorf("mp3: couldn't read sideinfo %d bytes at pos %d: %v",
+	n := 0
+	var err error
+	for n < size && err == nil {
+		nn, err2 := getBytes(buf[n:])
+		n += nn
+		err = err2
+	}
+	if n < size {
+		if err == io.EOF {
+			return fmt.Errorf("mp3: unexpected EOF at getSideinfo")
+		}
+		return fmt.Errorf("mp3: couldn't read sideinfo %d bytes at pos %d: %v",
 			size, Get_Filepos(), err)
-		return
 	}
 	theSideInfo.vec = buf[:n]
 	theSideInfo.idx = 0
+	return nil
 }
 
 func getSideBits(num int) int {