g729a_dec_lag3.c

来自「DSP上优化的G.729A代码」· C语言 代码 · 共 53 行

#include "../Common/typedef.h"
#include "../Include/G729A_basic_op.h"
#include "../Include/G729A_ld8a.h"

void G729ADec_lag3(Word16 index, Word16 pit_min, Word16 pit_max, Word16 i_subfr, Word16 *T0, Word16 *T0_frac)
{
	Word16 i;
	Word16 T0_min, T0_max;
	
	if (i_subfr == 0)                  
	{
		if (G729Asub_s(index, 197) < 0)
		{
			*T0 = G729Aadd_s(G729Amult(G729Aadd_s(index, 2), 10923), 19);
			
			i = G729Aadd_s(G729Aadd_s(*T0, *T0), *T0);
			*T0_frac = G729Aadd_s(G729Asub_s(index, i), 58);
		}
		else
		{
			*T0 = G729Asub_s(index, 112);
			*T0_frac = 0;
		}
		
	}
	
	else   
	{
		T0_min = G729Asub_s(*T0, 5);
		if (G729Asub_s(T0_min, pit_min) < 0)
		{
			T0_min = pit_min;
		}
		
		T0_max = G729Aadd_s(T0_min, 9);
		if (G729Asub_s(T0_max, pit_max) > 0)
		{
			T0_max = pit_max;
			T0_min = G729Asub_s(T0_max, 9);
		}
		
		i = G729Asub_s(G729Amult(G729Aadd_s(index, 2), 10923), 1);
		*T0 = G729Aadd_s(i, T0_min);
		
		i = G729Aadd_s(G729Aadd_s(i, i), i);
		*T0_frac = G729Asub_s(G729Asub_s(index, 2), i);
	}
	
	return;
}