// Consume input data and store it in the full-image coefficient buffer.
// We read as much as one fully interleaved MCU row ("iMCU" row) per call,
// ie, v_samp_factor block rows for each component in the scan.
// Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
static CONSUME_INPUT consume_data(jpeg_decompress cinfo)
{
jpeg_lossy_d_codec lossyd = (jpeg_lossy_d_codec)cinfo.coef;
d_coef_controller coef = (d_coef_controller)lossyd.coef_private;
short[][][][] buffer = new short[MAX_COMPS_IN_SCAN][][][];
int[] buffer_ind = new int[MAX_COMPS_IN_SCAN];
// Align the buffers for the components used in this scan.
for (int ci = 0; ci < cinfo.comps_in_scan; ci++)
{
jpeg_component_info compptr = cinfo.cur_comp_info[ci];
buffer[ci] = coef.whole_image[compptr.component_index];
buffer_ind[ci] = (int)cinfo.input_iMCU_row * compptr.v_samp_factor;
// Note: entropy decoder expects buffer to be zeroed,
// but this is handled automatically by the memory manager
// because we requested a pre-zeroed array.
}
// Loop to process one whole iMCU row
for (int yoffset = coef.MCU_vert_offset; yoffset < coef.MCU_rows_per_iMCU_row; yoffset++)
{
for (uint MCU_col_num = coef.MCU_ctr; MCU_col_num < cinfo.MCUs_per_row; MCU_col_num++) // index of current MCU within row
{
// Construct list of pointers to DCT blocks belonging to this MCU
int blkn = 0; // index of current DCT block within MCU
for (int ci = 0; ci < cinfo.comps_in_scan; ci++)
{
jpeg_component_info compptr = cinfo.cur_comp_info[ci];
uint start_col = MCU_col_num * (uint)compptr.MCU_width;
for (int yindex = 0; yindex < compptr.MCU_height; yindex++)
{
short[][] buffer_ptr = buffer[ci][buffer_ind[ci] + yindex + yoffset];
uint buffer_ptr_ind = start_col;
for (int xindex = 0; xindex < compptr.MCU_width; xindex++)
{
coef.MCU_buffer[blkn++] = buffer_ptr[buffer_ptr_ind++];
}
}
}
// Try to fetch the MCU.
if (!lossyd.entropy_decode_mcu(cinfo, coef.MCU_buffer))
{
// Suspension forced; update state counters and exit
coef.MCU_vert_offset = yoffset;
coef.MCU_ctr = MCU_col_num;
return(CONSUME_INPUT.JPEG_SUSPENDED);
}
}
// Completed an MCU row, but perhaps not an iMCU row
coef.MCU_ctr = 0;
}
// Completed the iMCU row, advance counters for next one
if (++(cinfo.input_iMCU_row) < cinfo.total_iMCU_rows)
{
start_iMCU_row_d_coef(cinfo);
return(CONSUME_INPUT.JPEG_ROW_COMPLETED);
}
// Completed the scan
cinfo.inputctl.finish_input_pass(cinfo);
return(CONSUME_INPUT.JPEG_SCAN_COMPLETED);
}
// Decompress and return some data in the single-pass case.
// Always attempts to emit one fully interleaved MCU row ("iMCU" row).
// Input and output must run in lockstep since we have only a one-MCU buffer.
// Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
//
// NB: output_buf contains a plane for each component in image,
// which we index according to the component's SOF position.
static CONSUME_INPUT decompress_onepass(jpeg_decompress cinfo, byte[][][] output_buf)
{
jpeg_lossy_d_codec lossyd = (jpeg_lossy_d_codec)cinfo.coef;
d_coef_controller coef = (d_coef_controller)lossyd.coef_private;
uint last_MCU_col = cinfo.MCUs_per_row - 1;
uint last_iMCU_row = cinfo.total_iMCU_rows - 1;
// Loop to process as much as one whole iMCU row
for (int yoffset = coef.MCU_vert_offset; yoffset < coef.MCU_rows_per_iMCU_row; yoffset++)
{
for (uint MCU_col_num = coef.MCU_ctr; MCU_col_num <= last_MCU_col; MCU_col_num++) // index of current MCU within row
{
// Try to fetch an MCU. Entropy decoder expects buffer to be zeroed.
for (int i = 0; i < cinfo.blocks_in_MCU; i++)
{
for (int a = 0; a < DCTSIZE2; a++)
{
coef.MCU_buffer[i][a] = 0;
}
}
if (!lossyd.entropy_decode_mcu(cinfo, coef.MCU_buffer))
{
// Suspension forced; update state counters and exit
coef.MCU_vert_offset = yoffset;
coef.MCU_ctr = MCU_col_num;
return(CONSUME_INPUT.JPEG_SUSPENDED);
}
// Determine where data should go in output_buf and do the IDCT thing.
// We skip dummy blocks at the right and bottom edges (but blkn gets
// incremented past them!). Note the inner loop relies on having
// allocated the MCU_buffer[] blocks sequentially.
int blkn = 0; // index of current DCT block within MCU
for (int ci = 0; ci < cinfo.comps_in_scan; ci++)
{
jpeg_component_info compptr = cinfo.cur_comp_info[ci];
// Don't bother to IDCT an uninteresting component.
if (!compptr.component_needed)
{
blkn += (int)compptr.MCU_blocks;
continue;
}
inverse_DCT_method_ptr inverse_DCT = lossyd.inverse_DCT[compptr.component_index];
int useful_width = (MCU_col_num < last_MCU_col)?compptr.MCU_width:compptr.last_col_width;
byte[][] output_ptr = output_buf[compptr.component_index];
uint output_ptr_ind = (uint)yoffset * compptr.DCT_scaled_size;
uint start_col = MCU_col_num * (uint)compptr.MCU_sample_width;
for (int yindex = 0; yindex < compptr.MCU_height; yindex++)
{
if (cinfo.input_iMCU_row < last_iMCU_row || yoffset + yindex < compptr.last_row_height)
{
uint output_col = start_col;
for (int xindex = 0; xindex < useful_width; xindex++)
{
inverse_DCT(cinfo, compptr, coef.MCU_buffer[blkn + xindex], output_ptr, output_ptr_ind, output_col);
output_col += compptr.DCT_scaled_size;
}
}
blkn += compptr.MCU_width;
output_ptr_ind += compptr.DCT_scaled_size;
}
}
}
// Completed an MCU row, but perhaps not an iMCU row
coef.MCU_ctr = 0;
}
// Completed the iMCU row, advance counters for next one
cinfo.output_iMCU_row++;
if (++(cinfo.input_iMCU_row) < cinfo.total_iMCU_rows)
{
start_iMCU_row_d_coef(cinfo);
return(CONSUME_INPUT.JPEG_ROW_COMPLETED);
}
// Completed the scan
cinfo.inputctl.finish_input_pass(cinfo);
return(CONSUME_INPUT.JPEG_SCAN_COMPLETED);
}
