- if (predictor_coef_num > 0)
- for (i = 0; i < predictor_coef_num; i++) {
- int32_t val;
-
- val = buffer_out[i] + error_buffer[i+1];
- val = sign_extend(val, readsamplesize);
- buffer_out[i+1] = val;
- }
-
- /* 4 and 8 are very common cases (the only ones i've seen). these
- * should be unrolled and optimized
- */
-
- /* general case */
- if (predictor_coef_num > 0) {
- for (i = predictor_coef_num + 1; i < output_size; i++) {
- int j;
- int sum = 0;
- int outval;
- int error_val = error_buffer[i];
-
- for (j = 0; j < predictor_coef_num; j++) {
- sum += (buffer_out[predictor_coef_num-j] - buffer_out[0]) *
- predictor_coef_table[j];
- }
-
- outval = (1 << (predictor_quantitization-1)) + sum;
- outval = outval >> predictor_quantitization;
- outval = outval + buffer_out[0] + error_val;
- outval = sign_extend(outval, readsamplesize);
-
- buffer_out[predictor_coef_num+1] = outval;
-
- if (error_val > 0) {
- int predictor_num = predictor_coef_num - 1;
-
- while (predictor_num >= 0 && error_val > 0) {
- int val = buffer_out[0] - buffer_out[predictor_coef_num - predictor_num];
- int sign = sign_only(val);
-
- predictor_coef_table[predictor_num] -= sign;
-
- val *= sign; /* absolute value */
-
- error_val -= ((val >> predictor_quantitization) *
- (predictor_coef_num - predictor_num));
-
- predictor_num--;
- }
- } else if (error_val < 0) {
- int predictor_num = predictor_coef_num - 1;
-
- while (predictor_num >= 0 && error_val < 0) {
- int val = buffer_out[0] - buffer_out[predictor_coef_num - predictor_num];
- int sign = - sign_only(val);
-
- predictor_coef_table[predictor_num] -= sign;
-
- val *= sign; /* neg value */
-
- error_val -= ((val >> predictor_quantitization) *
- (predictor_coef_num - predictor_num));
-
- predictor_num--;
- }
+ for (i = 1; i <= lpc_order; i++)
+ buffer_out[i] = sign_extend(buffer_out[i - 1] + error_buffer[i], bps);
+
+ /* NOTE: 4 and 8 are very common cases that could be optimized. */
+
+ for (; i < nb_samples; i++) {
+ int j;
+ int val = 0;
+ int error_val = error_buffer[i];
+ int error_sign;
+ int d = *pred++;
+
+ /* LPC prediction */
+ for (j = 0; j < lpc_order; j++)
+ val += (pred[j] - d) * lpc_coefs[j];
+ val = (val + (1 << (lpc_quant - 1))) >> lpc_quant;
+ val += d + error_val;
+ buffer_out[i] = sign_extend(val, bps);
+
+ /* adapt LPC coefficients */
+ error_sign = sign_only(error_val);
+ if (error_sign) {
+ for (j = 0; j < lpc_order && error_val * error_sign > 0; j++) {
+ int sign;
+ val = d - pred[j];
+ sign = sign_only(val) * error_sign;
+ lpc_coefs[j] -= sign;
+ val *= sign;
+ error_val -= (val >> lpc_quant) * (j + 1);