c8_3_3.c

dsp入门与实践一书的源代码

void ch_srch ( 	 unsigned char 			lambda[],
				 int					lam_deg,
				 unsigned char 			zeros[],
				 int 					*fail,
				 const  unsigned char 	alpha[],
				 int 					state[],
						 int					RS_T,
				const  unsigned char 	exp_table2[],
				const  unsigned char 	log_table[],
				const  unsigned char 	div_inv_table[]
			)
	{
				int i, j, ptr,result0;
				int *state0;
				int t0;
				const unsigned char *alpha0 = alpha ;
				state0 = state;
				ptr = 0;
	
		for (j = 0; j < RS_T; j++)
			{
				zeros[j] = 0;
				t0 = _gmpy4(alpha0[j], lambda[j+1]);
				state0[j] = t0;
			}

		for (i = 1; i <= 256; i++)
			{
				result0 = 1;
				for (j = 0; j < RS_T; j++)
				{
					result0 = (result0^state0[j]);
					t0 = _gmpy4(state0[j],alpha0[j]);
					state0[j] = t0;
				}
				if (!result0) zeros[ptr++]= i;
			}

		for (i = 0; i < RS_T; i++)
			{
				zeros[i] = exp_table2[zeros[i]];
			}
	}