private ReadResult decompress_smooth_data(ComponentBuffer[] output_buf)
{
/* Force some input to be done if we are getting ahead of the input. */
while (m_cinfo.m_input_scan_number <= m_cinfo.m_output_scan_number && !m_cinfo.m_inputctl.EOIReached())
{
if (m_cinfo.m_input_scan_number == m_cinfo.m_output_scan_number)
{
/* If input is working on current scan, we ordinarily want it to
* have completed the current row. But if input scan is DC,
* we want it to keep one row ahead so that next block row's DC
* values are up to date.
*/
int delta = (m_cinfo.m_Ss == 0) ? 1 : 0;
if (m_cinfo.m_input_iMCU_row > m_cinfo.m_output_iMCU_row + delta)
break;
}
if (m_cinfo.m_inputctl.consume_input() == ReadResult.JPEG_SUSPENDED)
return ReadResult.JPEG_SUSPENDED;
}
int last_iMCU_row = m_cinfo.m_total_iMCU_rows - 1;
/* OK, output from the virtual arrays. */
for (int ci = 0; ci < m_cinfo.m_num_components; ci++)
{
jpeg_component_info componentInfo = m_cinfo.Comp_info[ci];
/* Don't bother to IDCT an uninteresting component. */
if (!componentInfo.component_needed)
continue;
int block_rows;
int access_rows;
bool last_row;
/* Count non-dummy DCT block rows in this iMCU row. */
if (m_cinfo.m_output_iMCU_row < last_iMCU_row)
{
block_rows = componentInfo.V_samp_factor;
access_rows = block_rows * 2; /* this and next iMCU row */
last_row = false;
}
else
{
/* NB: can't use last_row_height here; it is input-side-dependent! */
block_rows = componentInfo.height_in_blocks % componentInfo.V_samp_factor;
if (block_rows == 0)
block_rows = componentInfo.V_samp_factor;
access_rows = block_rows; /* this iMCU row only */
last_row = true;
}
/* Align the virtual buffer for this component. */
JBLOCK[][] buffer = null;
bool first_row;
int bufferRowOffset = 0;
if (m_cinfo.m_output_iMCU_row > 0)
{
access_rows += componentInfo.V_samp_factor; /* prior iMCU row too */
buffer = m_whole_image[ci].Access((m_cinfo.m_output_iMCU_row - 1) * componentInfo.V_samp_factor, access_rows);
bufferRowOffset = componentInfo.V_samp_factor; /* point to current iMCU row */
first_row = false;
}
else
{
buffer = m_whole_image[ci].Access(0, access_rows);
first_row = true;
}
/* Fetch component-dependent info */
int coefBitsOffset = ci * SAVED_COEFS;
int Q00 = componentInfo.quant_table.quantval[0];
int Q01 = componentInfo.quant_table.quantval[Q01_POS];
int Q10 = componentInfo.quant_table.quantval[Q10_POS];
int Q20 = componentInfo.quant_table.quantval[Q20_POS];
int Q11 = componentInfo.quant_table.quantval[Q11_POS];
int Q02 = componentInfo.quant_table.quantval[Q02_POS];
int outputIndex = ci;
/* Loop over all DCT blocks to be processed. */
for (int block_row = 0; block_row < block_rows; block_row++)
{
int bufferIndex = bufferRowOffset + block_row;
int prev_block_row = 0;
if (first_row && block_row == 0)
prev_block_row = bufferIndex;
else
prev_block_row = bufferIndex - 1;
int next_block_row = 0;
if (last_row && block_row == block_rows - 1)
next_block_row = bufferIndex;
else
next_block_row = bufferIndex + 1;
/* We fetch the surrounding DC values using a sliding-register approach.
* Initialize all nine here so as to do the right thing on narrow pics.
*/
int DC1 = buffer[prev_block_row][0][0];
int DC2 = DC1;
int DC3 = DC1;
int DC4 = buffer[bufferIndex][0][0];
int DC5 = DC4;
int DC6 = DC4;
int DC7 = buffer[next_block_row][0][0];
int DC8 = DC7;
int DC9 = DC7;
int output_col = 0;
int last_block_column = componentInfo.Width_in_blocks - 1;
for (int block_num = 0; block_num <= last_block_column; block_num++)
{
/* Fetch current DCT block into workspace so we can modify it. */
JBLOCK workspace = new JBLOCK();
Buffer.BlockCopy(buffer[bufferIndex][0].data, 0, workspace.data, 0, workspace.data.Length * sizeof(short));
/* Update DC values */
if (block_num < last_block_column)
{
DC3 = buffer[prev_block_row][1][0];
DC6 = buffer[bufferIndex][1][0];
DC9 = buffer[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 */
int Al = m_coef_bits_latch[m_coef_bits_savedOffset + coefBitsOffset + 1];
if (Al != 0 && workspace[1] == 0)
{
int pred;
int num = 36 * Q00 * (DC4 - DC6);
if (num >= 0)
{
pred = ((Q01 << 7) + num) / (Q01 << 8);
if (Al > 0 && pred >= (1 << Al))
pred = (1 << Al) - 1;
}
else
{
pred = ((Q01 << 7) - num) / (Q01 << 8);
if (Al > 0 && pred >= (1 << Al))
pred = (1 << Al) - 1;
pred = -pred;
}
workspace[1] = (short) pred;
}
/* AC10 */
Al = m_coef_bits_latch[m_coef_bits_savedOffset + coefBitsOffset + 2];
if (Al != 0 && workspace[8] == 0)
{
int pred;
int num = 36 * Q00 * (DC2 - DC8);
if (num >= 0)
{
pred = ((Q10 << 7) + num) / (Q10 << 8);
if (Al > 0 && pred >= (1 << Al))
pred = (1 << Al) - 1;
}
else
{
pred = ((Q10 << 7) - num) / (Q10 << 8);
if (Al > 0 && pred >= (1 << Al))
pred = (1 << Al) - 1;
pred = -pred;
}
workspace[8] = (short) pred;
}
/* AC20 */
Al = m_coef_bits_latch[m_coef_bits_savedOffset + coefBitsOffset + 3];
if (Al != 0 && workspace[16] == 0)
{
int pred;
int num = 9 * Q00 * (DC2 + DC8 - 2 * DC5);
if (num >= 0)
{
pred = ((Q20 << 7) + num) / (Q20 << 8);
if (Al > 0 && pred >= (1 << Al))
pred = (1 << Al) - 1;
}
else
{
pred = ((Q20 << 7) - num) / (Q20 << 8);
if (Al > 0 && pred >= (1 << Al))
pred = (1 << Al) - 1;
pred = -pred;
}
workspace[16] = (short) pred;
}
/* AC11 */
Al = m_coef_bits_latch[m_coef_bits_savedOffset + coefBitsOffset + 4];
if (Al != 0 && workspace[9] == 0)
{
int pred;
int num = 5 * Q00 * (DC1 - DC3 - DC7 + DC9);
if (num >= 0)
{
pred = ((Q11 << 7) + num) / (Q11 << 8);
if (Al > 0 && pred >= (1 << Al))
pred = (1 << Al) - 1;
}
else
{
pred = ((Q11 << 7) - num) / (Q11 << 8);
if (Al > 0 && pred >= (1 << Al))
pred = (1 << Al) - 1;
pred = -pred;
}
workspace[9] = (short) pred;
}
/* AC02 */
Al = m_coef_bits_latch[m_coef_bits_savedOffset + coefBitsOffset + 5];
if (Al != 0 && workspace[2] == 0)
{
int pred;
int num = 9 * Q00 * (DC4 + DC6 - 2 * DC5);
if (num >= 0)
{
pred = ((Q02 << 7) + num) / (Q02 << 8);
if (Al > 0 && pred >= (1 << Al))
pred = (1 << Al) - 1;
}
else
{
pred = ((Q02 << 7) - num) / (Q02 << 8);
if (Al > 0 && pred >= (1 << Al))
pred = (1 << Al) - 1;
pred = -pred;
}
workspace[2] = (short) pred;
}
/* OK, do the IDCT */
m_cinfo.m_idct.inverse(componentInfo.Component_index, workspace.data, output_buf[outputIndex], 0, output_col);
/* Advance for next column */
DC1 = DC2;
DC2 = DC3;
DC4 = DC5;
DC5 = DC6;
DC7 = DC8;
DC8 = DC9;
bufferIndex++;
prev_block_row++;
next_block_row++;
output_col += componentInfo.DCT_h_scaled_size;
}
outputIndex += componentInfo.DCT_v_scaled_size;
}
}
m_cinfo.m_output_iMCU_row++;
if (m_cinfo.m_output_iMCU_row < m_cinfo.m_total_iMCU_rows)
return ReadResult.JPEG_ROW_COMPLETED;
return ReadResult.JPEG_SCAN_COMPLETED;
}