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, 47 insertions, 0 deletions

diff --git a/include/asterisk/ulaw.h b/include/asterisk/ulaw.h
index d9ab0d178..1ac079d54 100644
--- a/include/asterisk/ulaw.h
+++ b/include/asterisk/ulaw.h
@@ -23,21 +23,68 @@
 #ifndef _ASTERISK_ULAW_H
 #define _ASTERISK_ULAW_H
 
+
 /*! Init the ulaw conversion stuff */
 /*!
  * To init the ulaw to slinear conversion stuff, this needs to be run.
  */
 void ast_ulaw_init(void);
 
+#define AST_ULAW_BIT_LOSS  3
+#define AST_ULAW_STEP      (1 << AST_ULAW_BIT_LOSS)
+#define AST_ULAW_TAB_SIZE  (32768 / AST_ULAW_STEP + 1)
+#define AST_ULAW_SIGN_BIT  0x80
+
 /*! converts signed linear to mulaw */
 /*!
   */
+#ifndef G711_NEW_ALGORITHM
 extern unsigned char __ast_lin2mu[16384];
+#else
+extern unsigned char __ast_lin2mu[AST_ULAW_TAB_SIZE];
+#endif
 
 /*! help */
 extern short __ast_mulaw[256];
 
+#ifndef G711_NEW_ALGORITHM
+
 #define AST_LIN2MU(a) (__ast_lin2mu[((unsigned short)(a)) >> 2])
+
+#else
+
+#define AST_LIN2MU_LOOKUP(mag)											\
+	__ast_lin2mu[((mag) + AST_ULAW_STEP / 2) >> AST_ULAW_BIT_LOSS]
+
+
+/*! convert signed linear sample to sign-magnitude pair for u-Law */
+static inline void ast_ulaw_get_sign_mag(short sample, unsigned *sign, unsigned *mag)
+{
+       /* It may look illogical to retrive the sign this way in both cases,
+        * but this helps gcc eliminate the branch below and produces
+        * faster code */
+       *sign = ((unsigned short)sample >> 8) & AST_ULAW_SIGN_BIT;
+#if defined(G711_REDUCED_BRANCHING)
+       {
+               unsigned dual_mag = (-sample << 16) | (unsigned short)sample;
+               *mag = (dual_mag >> (*sign >> 3)) & 0xffffU;
+       }
+#else
+       if (sample < 0)
+               *mag = -sample;
+       else
+               *mag = sample;
+#endif /* G711_REDUCED_BRANCHING */
+}
+
+static inline unsigned char AST_LIN2MU(short sample)
+{
+       unsigned mag, sign;
+       ast_ulaw_get_sign_mag(sample, &sign, &mag);
+       return ~(sign | AST_LIN2MU_LOOKUP(mag));
+}
+#endif
+
 #define AST_MULAW(a) (__ast_mulaw[(a)])
 
 #endif /* _ASTERISK_ULAW_H */