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, 127 insertions, 11 deletions

diff --git a/main/alaw.c b/main/alaw.c
index d388d1e61..fbc99b0fe 100644
--- a/main/alaw.c
+++ b/main/alaw.c
@@ -18,7 +18,7 @@
 
 /*! \file
  *
- * \brief u-Law to Signed linear conversion
+ * \brief a-Law to Signed linear conversion
  *
  * \author Mark Spencer <markster@digium.com> 
  */
@@ -28,18 +28,20 @@
 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 
 #include "asterisk/alaw.h"
+#include "asterisk/logger.h"
 
+#ifndef G711_NEW_ALGORITHM
 #define AMI_MASK 0x55
 
-static inline unsigned char linear2alaw (short int linear)
+static inline unsigned char linear2alaw(short int linear)
 {
     int mask;
     int seg;
     int pcm_val;
     static int seg_end[8] =
-    {
-         0xFF, 0x1FF, 0x3FF, 0x7FF, 0xFFF, 0x1FFF, 0x3FFF, 0x7FFF
-    };
+		{
+			0xFF, 0x1FF, 0x3FF, 0x7FF, 0xFFF, 0x1FFF, 0x3FFF, 0x7FFF
+		};
     
     pcm_val = linear;
     if (pcm_val >= 0) {
@@ -50,7 +52,7 @@ static inline unsigned char linear2alaw (short int linear)
 	    mask = AMI_MASK;
 	    pcm_val = -pcm_val;
     }
-
+	
     /* Convert the scaled magnitude to segment number. */
     for (seg = 0;  seg < 8;  seg++) {
 	    if (pcm_val <= seg_end[seg])
@@ -59,13 +61,56 @@ static inline unsigned char linear2alaw (short int linear)
     /* Combine the sign, segment, and quantization bits. */
     return  ((seg << 4) | ((pcm_val >> ((seg)  ?  (seg + 3)  :  4)) & 0x0F)) ^ mask;
 }
-/*- End of function --------------------------------------------------------*/
+#else
+static unsigned char linear2alaw(short sample, int full_coding)
+{
+	static const unsigned exp_lut[128] = {
+		1,1,2,2,3,3,3,3,
+		4,4,4,4,4,4,4,4,
+		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,
+		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 alawbyte;
+	
+	ast_alaw_get_sign_mag(sample, &sign, &mag);
+	if (mag > 32767)
+		mag = 32767;        /* clip the magnitude for -32768 */
+	
+	exponent = exp_lut[(mag >> 8) & 0x7f];
+	mantissa = (mag >> (exponent + 3)) & 0x0f;
+	if (mag < 0x100)
+		exponent = 0;
+	
+	if (full_coding) {
+		/* full encoding, with sign and xform */
+		alawbyte = (unsigned char)(sign | (exponent << 4) | mantissa);
+		alawbyte ^= AST_ALAW_AMI_MASK;
+	} else {
+		/* half-cooked coding -- mantissa+exponent only (for lookup tab) */
+		alawbyte = (exponent << 4) | mantissa;
+	}
+	return alawbyte;
+}
+#endif
 
+#ifndef G711_NEW_ALGORITHM
 static inline short int alaw2linear (unsigned char alaw)
 {
     int i;
     int seg;
-
+	
     alaw ^= AMI_MASK;
     i = ((alaw & 0x0F) << 4);
     seg = (((int) alaw & 0x70) >> 4);
@@ -73,8 +118,31 @@ static inline short int alaw2linear (unsigned char alaw)
 	    i = (i + 0x100) << (seg - 1);
     return (short int) ((alaw & 0x80)  ?  i  :  -i);
 }
+#else
+static inline short alaw2linear(unsigned char alawbyte)
+{
+	unsigned exponent, mantissa;
+	short sample;
+	
+	alawbyte ^= AST_ALAW_AMI_MASK;
+	exponent = (alawbyte & 0x70) >> 4;
+	mantissa = alawbyte & 0x0f;
+	sample = (mantissa << 4) + 8 /* rounding error */;
+	if (exponent)
+		sample = (sample + 0x100) << (exponent - 1);
+	if (!(alawbyte & 0x80))
+		sample = -sample;
+	return sample;
+}
+#endif
+
 
+
+#ifndef G711_NEW_ALGORITHM
 unsigned char __ast_lin2a[8192];
+#else
+unsigned char __ast_lin2a[AST_ALAW_TAB_SIZE];
+#endif
 short __ast_alaw[256];
 
 void ast_alaw_init(void)
@@ -82,14 +150,62 @@ void ast_alaw_init(void)
 	int i;
 	/* 
 	 *  Set up mu-law conversion table
-	 */
+	 */ 
+#ifndef G711_NEW_ALGORITHM
 	for (i = 0; i < 256; i++) {
-	        __ast_alaw[i] = alaw2linear(i);
+		__ast_alaw[i] = alaw2linear(i);
 	}
 	/* set up the reverse (mu-law) conversion table */
 	for (i = -32768; i < 32768; i++) {
 		__ast_lin2a[((unsigned short)i) >> 3] = linear2alaw(i);
 	}
-
+#else
+	for (i = 0; i < 256; i++) {
+		__ast_alaw[i] = alaw2linear(i);
+	}
+	/* set up the reverse (a-law) conversion table */
+	for (i = 0; i <= 32768; i += AST_ALAW_STEP) {
+		AST_LIN2A_LOOKUP(i) = linear2alaw(i, 0 /* half-cooked */);
+	}
+#endif
+	
+#ifdef TEST_CODING_TABLES
+	for (i = -32768; i < 32768; ++i) {
+#ifndef G711_NEW_ALGORITHM
+		unsigned char e1 = linear2alaw(i);
+#else
+		unsigned char e1 = linear2alaw(i, 1);
+#endif
+		short d1 = alaw2linear(e1);
+		unsigned char e2 = AST_LIN2A(i);
+		short d2 = alaw2linear(e2);
+		short d3 = AST_ALAW(e1);
+		
+		if (e1 != e2 || d1 != d3 || d2 != d3) {
+			ast_log(LOG_WARNING, "a-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, "a-Law coding tables test complete.\n");
+#endif /* TEST_CODING_TABLES */
+	
+#ifdef TEST_TANDEM_TRANSCODING
+	/* tandem transcoding test */
+	for (i = -32768; i < 32768; ++i) {
+		unsigned char e1 = AST_LIN2A(i);
+		short d1 = AST_ALAW(e1);
+		unsigned char e2 = AST_LIN2A(d1);
+		short d2 = AST_ALAW(e2);
+		unsigned char e3 = AST_LIN2A(d2);
+		short d3 = AST_ALAW(e3);
+		
+		if (e1 != e2 || e2 != e3 || d1 != d2 || d2 != d3) {
+			ast_log(LOG_WARNING, "a-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, "a-Law tandem transcoding test complete.\n");
+#endif /* TEST_TANDEM_TRANSCODING */
+	
 }