ulaw.h File Reference

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Defines
#define	AST_LIN2MU(a)   (__ast_lin2mu[((unsigned short)(a)) >> 2])
#define	AST_MULAW(a)   (__ast_mulaw[(a)])
Functions
void	ast_ulaw_init (void)
	Init the ulaw conversion stuff.
Variables
unsigned char	__ast_lin2mu [16384]
	converts signed linear to mulaw
short	__ast_mulaw [256]
	help

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Define Documentation

#define AST_LIN2MU (  a   )     (__ast_lin2mu[((unsigned short)(a)) >> 2])

Definition at line 31 of file ulaw.h.

#define AST_MULAW (  a   )     (__ast_mulaw[(a)])

Definition at line 32 of file ulaw.h. Referenced by ast_dsp_process(), and tdd_feed().

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Function Documentation

void ast_ulaw_init (  void   )

Init the ulaw conversion stuff. To init the ulaw to slinear conversion stuff, this needs to be run. Definition at line 62 of file ulaw.c. References __ast_lin2mu, and __ast_mulaw. Referenced by main(). { int i; /* * Set up mu-law conversion table */ 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; __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); } }

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Variable Documentation

unsigned char __ast_lin2mu[16384]

converts signed linear to mulaw Definition at line 20 of file ulaw.c. Referenced by ast_ulaw_init().

short __ast_mulaw[256]

help Definition at line 21 of file ulaw.c. Referenced by ast_ulaw_init().

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