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Last updated: Sat Feb 3 05:01:57 2007
Asterisk developer's documentation :: Codename Pineapple
ulaw.h File Reference
Definition in file ulaw.h.
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Go to the source code of this file.
Defines | |
| #define | AST_LIN2MU(a) (__ast_lin2mu[((unsigned short)(a)) >> 2]) |
| #define | AST_MULAW(a) (__ast_mulaw[(a)]) |
Functions | |
| void | ast_ulaw_init (void) |
| Set up mu-law conversion table. | |
Variables | |
| unsigned char | __ast_lin2mu [16384] |
| short | __ast_mulaw [256] |
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Definition at line 40 of file ulaw.h. Referenced by fill_rxgain(), and fill_txgain(). |
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Definition at line 41 of file ulaw.h. Referenced by ast_dsp_process(), fill_rxgain(), fill_txgain(), and tdd_feed(). |
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Set up mu-law conversion table. To init the ulaw to slinear conversion stuff, this needs to be run. Definition at line 85 of file ulaw.c. 00086 { 00087 int i; 00088 for (i = 0; i < 256; i++) { 00089 short mu, e, f, y; 00090 static short etab[] = {0,132,396,924,1980,4092,8316,16764}; 00091 00092 mu = 255 - i; 00093 e = (mu & 0x70) / 16; 00094 f = mu & 0x0f; 00095 y = f * (1 << (e + 3)); 00096 y += etab[e]; 00097 if (mu & 0x80) 00098 y = -y; 00099 __ast_mulaw[i] = y; 00100 } 00101 /* set up the reverse (mu-law) conversion table */ 00102 for (i = -32768; i < 32768; i++) { 00103 __ast_lin2mu[((unsigned short)i) >> 2] = linear2ulaw(i); 00104 } 00105 }
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