1 files changed, 165 insertions, 0 deletions
diff --git a/src/libmpg123/dxhead.c b/src/libmpg123/dxhead.c
new file mode 100755
index 0000000..21b5ceb
--- /dev/null
+++ b/src/libmpg123/dxhead.c
@@ -0,0 +1,165 @@
+/* ---- DXhead.c --------------------------------------------
+ *
+ *
+ * decoder MPEG Layer III handle Xing header
+ *
+ * mod 12/7/98 add vbr scale
+ *
+ * Copyright 1998 Xing Technology Corp.
+ * -----------------------------------------------------------
+ */  
+#include <stdlib.h>
+#include <stdio.h>
+#include <float.h>
+#include <math.h>
+#include "dxhead.h"
+
+/* 4   Xing
+ * 4   flags
+ * 4   frames
+ * 4   bytes
+ * 100 toc
+ */ 
+
+/*-------------------------------------------------------------*/ 
+static int ExtractI4(unsigned char *buf) 
+{
+	int x;
+	
+	/* big endian extract */ 
+	x = buf[0];
+	x <<= 8;
+	x |= buf[1];
+	x <<= 8;
+	x |= buf[2];
+	x <<= 8;
+	x |= buf[3];
+	return x;
+}
+
+/*-------------------------------------------------------------*/ 
+int mpg123_get_xing_header(XHEADDATA * X, unsigned char *buf)
+{	
+	int i, head_flags;
+	int h_id, h_mode, h_sr_index;
+	static int sr_table[4] =
+	{44100, 48000, 32000, 99999};
+	
+	/* get Xing header data */ 
+	X->flags = 0;	/* clear to null incase fail */
+
+	/* get selected MPEG header data */ 
+	h_id = (buf[1] >> 3) & 1;
+	h_sr_index = (buf[2] >> 2) & 3;
+	h_mode = (buf[3] >> 6) & 3;
+	
+		
+		
+	/* determine offset of header */ 
+	if (h_id)
+	{			/* mpeg1 */
+		if (h_mode != 3)
+			buf += (32 + 4);
+		else
+			buf += (17 + 4);
+	}
+	else
+	{			/* mpeg2 */
+		if (h_mode != 3)
+			buf += (17 + 4);
+		else
+			buf += (9 + 4);
+	}
+		
+	if (buf[0] != 'X')
+		return 0;	/* fail */
+	if (buf[1] != 'i')
+		return 0;	/* header not found */
+	if (buf[2] != 'n')
+		return 0;
+	if (buf[3] != 'g')
+		return 0;
+	buf += 4;
+		
+	X->h_id = h_id;
+	X->samprate = sr_table[h_sr_index];
+	if (h_id == 0)
+		X->samprate >>= 1;
+	head_flags = X->flags = ExtractI4(buf);
+	buf += 4;		/* get flags */
+	
+	if (head_flags & FRAMES_FLAG)
+	{
+		X->frames = ExtractI4(buf);
+		buf += 4;
+	}
+	if (head_flags & BYTES_FLAG)
+	{
+		X->bytes = ExtractI4(buf);
+		buf += 4;
+	}
+	
+	if (head_flags & TOC_FLAG)
+	{
+		if (X->toc != NULL)
+		{
+			for (i = 0; i < 100; i++)
+				X->toc[i] = buf[i];
+		}
+		buf += 100;
+	}
+		
+	X->vbr_scale = -1;
+	if (head_flags & VBR_SCALE_FLAG)
+	{
+		X->vbr_scale = ExtractI4(buf);
+		buf += 4;
+	}
+	
+		
+/*if( X->toc != NULL ) {
+ *for(i=0;i<100;i++) {
+ *    if( (i%10) == 0 ) printf("\n");
+ *    printf(" %3d", (int)(X->toc[i]));
+ *}
+ *}
+ */ 
+	
+	return 1;	/* success */
+}
+
+/*-------------------------------------------------------------*/ 
+int mpg123_seek_point(unsigned char TOC[100], int file_bytes, float percent) 
+{
+	
+	/* interpolate in TOC to get file seek point in bytes */ 
+	int a, seekpoint;
+	float fa, fb, fx;
+		
+	if (percent < 0.0f)
+		percent = 0.0f;
+	
+	if (percent > 100.0f)
+		percent = 100.0f;
+	
+	a = (int) percent;
+	
+	if (a > 99)
+		a = 99;
+	fa = TOC[a];
+	
+	if (a < 99)
+	{
+		fb = TOC[a + 1];
+	}
+	else
+	{
+		fb = 256.0f;
+	}
+	
+	fx = fa + (fb - fa) * (percent - a);
+	seekpoint = (int) ((1.0f / 256.0f) * fx * file_bytes);
+	return seekpoint;
+}
+
+/*-------------------------------------------------------------*/