This change set fixes bug 8126 in trunk. It is implemented via compile time options, activated via the menuselect stuff, which defaults to the old way. non-zero sample data added. Translate tables expressed in microseconds instead of milliseconds, with 5-digit data now instead of 3, giving 2 more digits of precision.

git-svn-id: http://svn.digium.com/svn/asterisk/trunk@80113 f38db490-d61c-443f-a65b-d21fe96a405b

1 files changed, 153 insertions, 12 deletions

diff --git a/main/ulaw.c b/main/ulaw.c
index 2735f6cce..8e47d8a77 100644
--- a/main/ulaw.c
+++ b/main/ulaw.c
@@ -28,15 +28,25 @@
 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 
 #include "asterisk/ulaw.h"
+#include "asterisk/logger.h"
 
+#if 0
+/* ZEROTRAP is the military recommendation to improve the encryption
+ * of u-Law traffic. It is irrelevant with modern encryption systems
+ * like AES, and will simply degrade the signal quality.
+ * ZEROTRAP is not implemented in AST_LIN2MU and so the coding table
+ * tests will fail if you use it */
 #define ZEROTRAP    /*!< turn on the trap as per the MIL-STD */
+#endif
+
 #define BIAS 0x84   /*!< define the add-in bias for 16 bit samples */
 #define CLIP 32635
 
+#ifndef G711_NEW_ALGORITHM
+
 unsigned char __ast_lin2mu[16384];
 short __ast_mulaw[256];
 
-
 static unsigned char linear2ulaw(short sample)
 {
 	static int exp_lut[256] = {
@@ -58,26 +68,102 @@ static unsigned char linear2ulaw(short sample)
 		7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7 };
 	int sign, exponent, mantissa;
 	unsigned char ulawbyte;
-
+	
 	/* Get the sample into sign-magnitude. */
 	sign = (sample >> 8) & 0x80;          /* set aside the sign */
-	if (sign != 0) 
+	if (sign != 0)
 		sample = -sample;              /* get magnitude */
 	if (sample > CLIP)
 		sample = CLIP;             /* clip the magnitude */
-
+	
 	/* Convert from 16 bit linear to ulaw. */
 	sample = sample + BIAS;
 	exponent = exp_lut[(sample >> 7) & 0xFF];
 	mantissa = (sample >> (exponent + 3)) & 0x0F;
 	ulawbyte = ~(sign | (exponent << 4) | mantissa);
+	
 #ifdef ZEROTRAP
 	if (ulawbyte == 0)
 		ulawbyte = 0x02;   /* optional CCITT trap */
 #endif
+	
+	return ulawbyte;
+}
+
+#else
+
+unsigned char __ast_lin2mu[AST_ULAW_TAB_SIZE];
+short __ast_mulaw[256];
+
+static unsigned char linear2ulaw(short sample, int full_coding)
+{
+	static const unsigned exp_lut[256] = {
+		0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,
+		4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
+		5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
+		5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
+		6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
+		6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
+		6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
+		6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
+		7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+		7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+		7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+		7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+		7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+		7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+		7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+		7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7 };
+	unsigned sign, exponent, mantissa, mag;
+	unsigned char ulawbyte;
+	
+	/* Get the sample into sign-magnitude. */
+	ast_ulaw_get_sign_mag(sample, &sign, &mag);
+	if (mag > CLIP)
+		mag = CLIP;                /* clip the magnitude */
+	
+	sign = (sample >> 8) & 0x80;          /* set aside the sign */
+	if (sign != 0) 
+		sample = -sample;              /* get magnitude */
+	if (sample > CLIP)
+		sample = CLIP;             /* clip the magnitude */
+	
+	/* Convert from 16 bit linear to ulaw. */
+	mag += BIAS;
+	exponent = exp_lut[(mag >> 7) & 0xFF];
+	mantissa = (mag >> (exponent + 3)) & 0x0F;
+	
+	if (full_coding) {
+		/* full encoding, with sign and xform */
+		ulawbyte = ~(sign | (exponent << 4) | mantissa);
+#ifdef ZEROTRAP
+		if (ulawbyte == 0)
+			ulawbyte = 0x02;   /* optional CCITT trap */
+#endif
+	} else {
+		/* half-cooked coding -- mantissa+exponent only (for lookup tab) */
+		ulawbyte = (exponent << 4) | mantissa;
+	}
 
 	return ulawbyte;
 }
+	
+static inline short ulaw2linear(unsigned char ulawbyte)
+{
+	unsigned exponent, mantissa;
+	short sample;
+	static const short etab[]={0,132,396,924,1980,4092,8316,16764};
+	
+	ulawbyte = ~ulawbyte;
+	exponent = (ulawbyte & 0x70) >> 4;
+	mantissa = ulawbyte & 0x0f;
+	sample = mantissa << (exponent + 3);
+	sample += etab[exponent];
+	if (ulawbyte & 0x80)
+		sample = -sample;
+	return sample;
+}
+#endif
 
 /*!
  * \brief  Set up mu-law conversion table
@@ -85,22 +171,77 @@ static unsigned char linear2ulaw(short sample)
 void ast_ulaw_init(void)
 {
 	int i;
-	for (i = 0; i < 256; i++) {
-		short mu, e, f, y;
-		static short etab[] = {0,132,396,924,1980,4092,8316,16764};
-
-		mu = 255 - i;
-		e = (mu & 0x70) / 16;
+	
+	/*
+	 *  Set up mu-law conversion table
+	 */
+#ifndef G711_NEW_ALGORITHM
+	for (i = 0;i < 256;i++) {
+		short mu,e,f,y;
+		static short etab[]={0,132,396,924,1980,4092,8316,16764};
+		
+		mu = 255-i;
+		e = (mu & 0x70)/16;
 		f = mu & 0x0f;
 		y = f * (1 << (e + 3));
 		y += etab[e];
-		if (mu & 0x80)
-			y = -y;
+		if (mu & 0x80) y = -y;
 		__ast_mulaw[i] = y;
 	}
 	/* set up the reverse (mu-law) conversion table */
 	for (i = -32768; i < 32768; i++) {
 		__ast_lin2mu[((unsigned short)i) >> 2] = linear2ulaw(i);
 	}
+#else
+	
+	for (i = 0; i < 256; i++) {
+		__ast_mulaw[i] = ulaw2linear(i);
+	}
+	/* set up the reverse (mu-law) conversion table */
+	for (i = 0; i <= 32768; i += AST_ULAW_STEP) {
+		AST_LIN2MU_LOOKUP(i) = linear2ulaw(i, 0 /* half-cooked */);
+	}
+#endif
+	
+#ifdef TEST_CODING_TABLES
+	for (i = -32768; i < 32768; ++i) {
+#ifndef G711_NEW_ALGORITHM
+		unsigned char e1 = linear2ulaw(i);
+#else
+		unsigned char e1 = linear2ulaw(i, 1);
+#endif
+		short d1 = ulaw2linear(e1);
+		unsigned char e2 = AST_LIN2MU(i);
+		short d2 = ulaw2linear(e2);
+		short d3 = AST_MULAW(e1);
+		
+		if (e1 != e2 || d1 != d3 || d2 != d3) {
+			ast_log(LOG_WARNING, "u-Law coding tables test failed on %d: e1=%u, e2=%u, d1=%d, d2=%d\n",
+					i, (unsigned)e1, (unsigned)e2, (int)d1, (int)d2);
+		}
+	}
+	ast_log(LOG_NOTICE, "u-Law coding table test complete.\n");
+#endif /* TEST_CODING_TABLES */
+	
+#ifdef TEST_TANDEM_TRANSCODING
+	/* tandem transcoding test */
+	for (i = -32768; i < 32768; ++i) {
+		unsigned char e1 = AST_LIN2MU(i);
+		short d1 = AST_MULAW(e1);
+		unsigned char e2 = AST_LIN2MU(d1);
+		short d2 = AST_MULAW(e2);
+		unsigned char e3 = AST_LIN2MU(d2);
+		short d3 = AST_MULAW(e3);
+		
+		if (i < 0 && e1 == 0x7f && e2 == 0xff && e3 == 0xff)
+			continue; /* known and normal negative 0 case */
+		
+		if (e1 != e2 || e2 != e3 || d1 != d2 || d2 != d3) {
+			ast_log(LOG_WARNING, "u-Law tandem transcoding test failed on %d: e1=%u, e2=%u, d1=%d, d2=%d, d3=%d\n",
+					i, (unsigned)e1, (unsigned)e2, (int)d1, (int)d2, (int)d3);
+		}
+	}
+	ast_log(LOG_NOTICE, "u-Law tandem transcoding test complete.\n");
+#endif /* TEST_TANDEM_TRANSCODING */
 }