audio/mp3: Make Get_Byte a Go function

audio/mp3/decode_notjs.go

@@ -39,14 +39,28 @@ var (
 
 //export Read_CRC
 func Read_CRC() C.int {
-	if Get_Byte() == eof || Get_Byte() == eof {
-		return C.FALSE
+	buf := make([]int, 2)
+	n := 0
+	var err error
+	for n < 2 && err == nil {
+		nn, err2 := getBytes(buf[n:])
+		n += nn
+		err = err2
+	}
+	if err == io.EOF {
+		if n < 2 {
+			return C.ERROR
+		}
+		return C.OK
+	}
+	if err != nil {
+		g_error = err
+		return C.ERROR
 	}
 	return C.OK
 }
 
-//export Get_Byte
-func Get_Byte() C.unsigned {
+func getByte() (uint8, error) {
 	for len(readerCache) == 0 && !readerEOF {
 		buf := make([]uint8, 4096)
 		n, err := reader.Read(buf)
@@ -55,26 +69,26 @@ func Get_Byte() C.unsigned {
 			if err == io.EOF {
 				readerEOF = true
 			} else {
-				panic(err)
+				return 0, err
 			}
 		}
 	}
 	if len(readerCache) == 0 {
-		return eof
+		return 0, io.EOF
 	}
 	b := readerCache[0]
 	readerCache = readerCache[1:]
 	readerPos++
-	return C.unsigned(b)
+	return b, nil
 }
 
 func getBytes(buf []int) (int, error) {
 	for i := range buf {
-		v := Get_Byte()
-		if v == eof {
+		v, err := getByte()
+		buf[i] = int(v)
+		if err == io.EOF {
 			return i, io.EOF
 		}
-		buf[i] = int(v)
 	}
 	return len(buf), nil
 }

audio/mp3/pdmp3.h

@@ -84,8 +84,6 @@ typedef struct { /* Scale factor band indices,for long and short windows */
 }
 t_sf_band_indices;
 
-unsigned Get_Byte(void);
-unsigned Get_Bytes(unsigned num, unsigned* data_vec);
 unsigned Get_Filepos(void);
 int Decode_L3(void);
 int Read_Frame(void);

audio/mp3/read.go

@@ -25,6 +25,7 @@ import "C"
 
 import (
 	"fmt"
+	"io"
 )
 
 func isHeader(header uint32) bool {
@@ -46,14 +47,24 @@ func isHeader(header uint32) bool {
 //export Read_Header
 func Read_Header() C.int {
 	/* Get the next four bytes from the bitstream */
-	b1 := uint32(Get_Byte())
-	b2 := uint32(Get_Byte())
-	b3 := uint32(Get_Byte())
-	b4 := uint32(Get_Byte())
-	/* If we got an End Of File condition we're done */
-	if (b1 == eof) || (b2 == eof) || (b3 == eof) || (b4 == eof) {
+	buf := make([]int, 4)
+	n := 0
+	var err error
+	for n < 4 && err == nil {
+		nn, err2 := getBytes(buf[n:])
+		n += nn
+		err = err2
+	}
+	if n < 4 {
+		if err != io.EOF {
+			g_error = err
+		}
 		return C.ERROR
 	}
+	b1 := uint32(buf[0])
+	b2 := uint32(buf[1])
+	b3 := uint32(buf[2])
+	b4 := uint32(buf[3])
 	header := (b1 << 24) | (b2 << 16) | (b3 << 8) | (b4 << 0)
 	for !isHeader(uint32(header)) {
 		/* No,so scan the bitstream one byte at a time until we find it or EOF */
@@ -62,12 +73,14 @@ func Read_Header() C.int {
 		b2 = b3
 		b3 = b4
 		/* Get one new byte from the bitstream */
-		b4 = uint32(Get_Byte())
-		/* If we got an End Of File condition we're done */
-		if b4 == eof {
+		b, err := getByte()
+		if err != nil {
+			if err != io.EOF {
+				g_error = err
+			}
 			return C.ERROR
 		}
-		/* Make up the new header */
+		b4 = uint32(b)
 		header = (b1 << 24) | (b2 << 16) | (b3 << 8) | (b4 << 0)
 	} /* while... */
 	/* If we get here we've found the sync word,and can decode the header