- /* Fetch current DCT block into workspace so we can modify it. */
- jcopy_block_row(buffer_ptr, (JBLOCKROW) workspace, (JDIMENSION) 1);
- /* Update DC values */
- if (block_num < last_block_column) {
- DC3 = (int) prev_block_row[1][0];
- DC6 = (int) buffer_ptr[1][0];
- DC9 = (int) next_block_row[1][0];
- }
- /* Compute coefficient estimates per K.8.
- * An estimate is applied only if coefficient is still zero,
- * and is not known to be fully accurate.
- */
- /* AC01 */
- if ((Al=coef_bits[1]) != 0 && workspace[1] == 0) {
- num = 36 * Q00 * (DC4 - DC6);
- if (num >= 0) {
- pred = (int) (((Q01<<7) + num) / (Q01<<8));
- if (Al > 0 && pred >= (1<<Al))
- pred = (1<<Al)-1;
- } else {
- pred = (int) (((Q01<<7) - num) / (Q01<<8));
- if (Al > 0 && pred >= (1<<Al))
- pred = (1<<Al)-1;
- pred = -pred;
- }
- workspace[1] = (JCOEF) pred;
- }
- /* AC10 */
- if ((Al=coef_bits[2]) != 0 && workspace[8] == 0) {
- num = 36 * Q00 * (DC2 - DC8);
- if (num >= 0) {
- pred = (int) (((Q10<<7) + num) / (Q10<<8));
- if (Al > 0 && pred >= (1<<Al))
- pred = (1<<Al)-1;
- } else {
- pred = (int) (((Q10<<7) - num) / (Q10<<8));
- if (Al > 0 && pred >= (1<<Al))
- pred = (1<<Al)-1;
- pred = -pred;
- }
- workspace[8] = (JCOEF) pred;
- }
- /* AC20 */
- if ((Al=coef_bits[3]) != 0 && workspace[16] == 0) {
- num = 9 * Q00 * (DC2 + DC8 - 2*DC5);
- if (num >= 0) {
- pred = (int) (((Q20<<7) + num) / (Q20<<8));
- if (Al > 0 && pred >= (1<<Al))
- pred = (1<<Al)-1;
- } else {
- pred = (int) (((Q20<<7) - num) / (Q20<<8));
- if (Al > 0 && pred >= (1<<Al))
- pred = (1<<Al)-1;
- pred = -pred;
- }
- workspace[16] = (JCOEF) pred;
- }
- /* AC11 */
- if ((Al=coef_bits[4]) != 0 && workspace[9] == 0) {
- num = 5 * Q00 * (DC1 - DC3 - DC7 + DC9);
- if (num >= 0) {
- pred = (int) (((Q11<<7) + num) / (Q11<<8));
- if (Al > 0 && pred >= (1<<Al))
- pred = (1<<Al)-1;
- } else {
- pred = (int) (((Q11<<7) - num) / (Q11<<8));
- if (Al > 0 && pred >= (1<<Al))
- pred = (1<<Al)-1;
- pred = -pred;
- }
- workspace[9] = (JCOEF) pred;
- }
- /* AC02 */
- if ((Al=coef_bits[5]) != 0 && workspace[2] == 0) {
- num = 9 * Q00 * (DC4 + DC6 - 2*DC5);
- if (num >= 0) {
- pred = (int) (((Q02<<7) + num) / (Q02<<8));
- if (Al > 0 && pred >= (1<<Al))
- pred = (1<<Al)-1;
- } else {
- pred = (int) (((Q02<<7) - num) / (Q02<<8));
- if (Al > 0 && pred >= (1<<Al))
- pred = (1<<Al)-1;
- pred = -pred;
- }
- workspace[2] = (JCOEF) pred;
- }
- /* OK, do the IDCT */
- (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) workspace,
- output_ptr, output_col);
- /* Advance for next column */
- DC1 = DC2; DC2 = DC3;
- DC4 = DC5; DC5 = DC6;
- DC7 = DC8; DC8 = DC9;
- buffer_ptr++, prev_block_row++, next_block_row++;
- output_col += compptr->DCT_scaled_size;
+ /* Fetch current DCT block into workspace so we can modify it. */
+ jcopy_block_row(buffer_ptr, (JBLOCKROW) workspace, (JDIMENSION) 1);
+ /* Update DC values */
+ if (block_num < last_block_column) {
+ DC3 = (int) prev_block_row[1][0];
+ DC6 = (int) buffer_ptr[1][0];
+ DC9 = (int) next_block_row[1][0];
+ }
+ /* Compute coefficient estimates per K.8.
+ * An estimate is applied only if coefficient is still zero,
+ * and is not known to be fully accurate.
+ */
+ /* AC01 */
+ if ((Al=coef_bits[1]) != 0 && workspace[1] == 0) {
+ num = 36 * Q00 * (DC4 - DC6);
+ if (num >= 0) {
+ pred = (int) (((Q01<<7) + num) / (Q01<<8));
+ if (Al > 0 && pred >= (1<<Al))
+ pred = (1<<Al)-1;
+ } else {
+ pred = (int) (((Q01<<7) - num) / (Q01<<8));
+ if (Al > 0 && pred >= (1<<Al))
+ pred = (1<<Al)-1;
+ pred = -pred;
+ }
+ workspace[1] = (JCOEF) pred;
+ }
+ /* AC10 */
+ if ((Al=coef_bits[2]) != 0 && workspace[8] == 0) {
+ num = 36 * Q00 * (DC2 - DC8);
+ if (num >= 0) {
+ pred = (int) (((Q10<<7) + num) / (Q10<<8));
+ if (Al > 0 && pred >= (1<<Al))
+ pred = (1<<Al)-1;
+ } else {
+ pred = (int) (((Q10<<7) - num) / (Q10<<8));
+ if (Al > 0 && pred >= (1<<Al))
+ pred = (1<<Al)-1;
+ pred = -pred;
+ }
+ workspace[8] = (JCOEF) pred;
+ }
+ /* AC20 */
+ if ((Al=coef_bits[3]) != 0 && workspace[16] == 0) {
+ num = 9 * Q00 * (DC2 + DC8 - 2*DC5);
+ if (num >= 0) {
+ pred = (int) (((Q20<<7) + num) / (Q20<<8));
+ if (Al > 0 && pred >= (1<<Al))
+ pred = (1<<Al)-1;
+ } else {
+ pred = (int) (((Q20<<7) - num) / (Q20<<8));
+ if (Al > 0 && pred >= (1<<Al))
+ pred = (1<<Al)-1;
+ pred = -pred;
+ }
+ workspace[16] = (JCOEF) pred;
+ }
+ /* AC11 */
+ if ((Al=coef_bits[4]) != 0 && workspace[9] == 0) {
+ num = 5 * Q00 * (DC1 - DC3 - DC7 + DC9);
+ if (num >= 0) {
+ pred = (int) (((Q11<<7) + num) / (Q11<<8));
+ if (Al > 0 && pred >= (1<<Al))
+ pred = (1<<Al)-1;
+ } else {
+ pred = (int) (((Q11<<7) - num) / (Q11<<8));
+ if (Al > 0 && pred >= (1<<Al))
+ pred = (1<<Al)-1;
+ pred = -pred;
+ }
+ workspace[9] = (JCOEF) pred;
+ }
+ /* AC02 */
+ if ((Al=coef_bits[5]) != 0 && workspace[2] == 0) {
+ num = 9 * Q00 * (DC4 + DC6 - 2*DC5);
+ if (num >= 0) {
+ pred = (int) (((Q02<<7) + num) / (Q02<<8));
+ if (Al > 0 && pred >= (1<<Al))
+ pred = (1<<Al)-1;
+ } else {
+ pred = (int) (((Q02<<7) - num) / (Q02<<8));
+ if (Al > 0 && pred >= (1<<Al))
+ pred = (1<<Al)-1;
+ pred = -pred;
+ }
+ workspace[2] = (JCOEF) pred;
+ }
+ /* OK, do the IDCT */
+ (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) workspace,
+ output_ptr, output_col);
+ /* Advance for next column */
+ DC1 = DC2; DC2 = DC3;
+ DC4 = DC5; DC5 = DC6;
+ DC7 = DC8; DC8 = DC9;
+ buffer_ptr++, prev_block_row++, next_block_row++;
+ output_col += compptr->DCT_scaled_size;