// * jdcoefct.c // * // * Copyright (C) 1994-1995, Thomas G. Lane. // * This file is part of the Independent JPEG Group's software. // * For conditions of distribution and use, see the accompanying README file. // * // * This file contains the coefficient buffer controller for decompression. // * This controller is the top level of the JPEG decompressor proper. // * The coefficient buffer lies between entropy decoding and inverse-DCT steps. // * // * In buffered-image mode, this controller is the interface between // * input-oriented processing and output-oriented processing. // * Also, the input side (only) is used when reading a file for transcoding. #define JPEG_INTERNALS #include "JINCLUDE.h" #include "JPEGLIB.h" // Block smoothing is only applicable for progressive JPEG, so: #ifndef D_PROGRESSIVE_SUPPORTED #undef BLOCK_SMOOTHING_SUPPORTED #endif // Private buffer controller object typedef struct { struct jpeg_d_coef_controller pub; // public fields // These variables keep track of the current location of the input side. // cinfo->input_iMCU_row is also used for this. JDIMENSION MCU_ctr; // counts MCUs processed in current row int MCU_vert_offset; // counts MCU rows within iMCU row int MCU_rows_per_iMCU_row; // number of such rows needed // The output side's location is represented by cinfo->output_iMCU_row. // In single-pass modes, it's sufficient to buffer just one MCU. // * We allocate a workspace of D_MAX_BLOCKS_IN_MCU coefficient blocks, // * and let the entropy decoder write into that workspace each time. // * (On 80x86, the workspace is FAR even though it's not really very big; // * this is to keep the module interfaces unchanged when a large coefficient // * buffer is necessary.) // * In multi-pass modes, this array points to the current MCU's blocks // * within the virtual arrays; it is used only by the input side. JBLOCKROW MCU_buffer[D_MAX_BLOCKS_IN_MCU]; #ifdef D_MULTISCAN_FILES_SUPPORTED // In multi-pass modes, we need a virtual block array for each component. jvirt_barray_ptr whole_image[MAX_COMPONENTS]; #endif #ifdef BLOCK_SMOOTHING_SUPPORTED // When doing block smoothing, we latch coefficient Al values here int * coef_bits_latch; #define SAVED_COEFS 6 // we save coef_bits[0..5] #endif } my_coef_controller; typedef my_coef_controller * my_coef_ptr; // Forward declarations METHODDEF int decompress_onepass JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf)); #ifdef D_MULTISCAN_FILES_SUPPORTED METHODDEF int decompress_data JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf)); #endif #ifdef BLOCK_SMOOTHING_SUPPORTED LOCAL boolean smoothing_ok JPP((j_decompress_ptr cinfo)); METHODDEF int decompress_smooth_data JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf)); #endif LOCAL void start_iMCU_row (j_decompress_ptr cinfo) // Reset within-iMCU-row counters for a new row (input side) { my_coef_ptr coef = (my_coef_ptr) cinfo->coef; // In an interleaved scan, an MCU row is the same as an iMCU row. // * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows. // * But at the bottom of the image, process only what's left. if (cinfo->comps_in_scan > 1) { coef->MCU_rows_per_iMCU_row = 1; } else { if (cinfo->input_iMCU_row < (cinfo->total_iMCU_rows-1)) coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor; else coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height; } coef->MCU_ctr = 0; coef->MCU_vert_offset = 0; } // * Initialize for an input processing pass. METHODDEF void start_input_pass (j_decompress_ptr cinfo) { cinfo->input_iMCU_row = 0; start_iMCU_row(cinfo); } // * Initialize for an output processing pass. METHODDEF void start_output_pass (j_decompress_ptr cinfo) { #ifdef BLOCK_SMOOTHING_SUPPORTED my_coef_ptr coef = (my_coef_ptr) cinfo->coef; // If multipass, check to see whether to use block smoothing on this pass if (coef->pub.coef_arrays != NULL) { if (cinfo->do_block_smoothing && smoothing_ok(cinfo)) coef->pub.decompress_data = decompress_smooth_data; else coef->pub.decompress_data = decompress_data; } #endif cinfo->output_iMCU_row = 0; } // * 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. // * For single pass, this is the same as the components in the scan. METHODDEF int decompress_onepass (j_decompress_ptr cinfo, JSAMPIMAGE output_buf) { my_coef_ptr coef = (my_coef_ptr) cinfo->coef; JDIMENSION MCU_col_num; // index of current MCU within row JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1; JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; int blkn, ci, xindex, yindex, yoffset, useful_width; JSAMPARRAY output_ptr; JDIMENSION start_col, output_col; jpeg_component_info *compptr; inverse_DCT_method_ptr inverse_DCT; // Loop to process as much as one whole iMCU row for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row; yoffset++) { for (MCU_col_num = coef->MCU_ctr; MCU_col_num <= last_MCU_col; MCU_col_num++) { // Try to fetch an MCU. Entropy decoder expects buffer to be zeroed. jzero_far((void FAR *) coef->MCU_buffer[0], (size_t) (cinfo->blocks_in_MCU * SIZEOF(JBLOCK))); if (! (*cinfo->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 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. blkn = 0; // index of current DCT block within MCU for (ci = 0; ci < cinfo->comps_in_scan; ci++) { compptr = cinfo->cur_comp_info[ci]; // Don't bother to IDCT an uninteresting component. if (! compptr->component_needed) { blkn += compptr->MCU_blocks; continue; } inverse_DCT = cinfo->idct->inverse_DCT[compptr->component_index]; useful_width = (MCU_col_num < last_MCU_col) ? compptr->MCU_width : compptr->last_col_width; output_ptr = output_buf[ci] + yoffset * compptr->DCT_scaled_size; start_col = MCU_col_num * compptr->MCU_sample_width; for (yindex = 0; yindex < compptr->MCU_height; yindex++) { if (cinfo->input_iMCU_row < last_iMCU_row || yoffset+yindex < compptr->last_row_height) { output_col = start_col; for (xindex = 0; xindex < useful_width; xindex++) { (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) coef->MCU_buffer[blkn+xindex], output_ptr, output_col); output_col += compptr->DCT_scaled_size; } } blkn += compptr->MCU_width; output_ptr += 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(cinfo); return JPEG_ROW_COMPLETED; } // Completed the scan (*cinfo->inputctl->finish_input_pass) (cinfo); return JPEG_SCAN_COMPLETED; } // * Dummy consume-input routine for single-pass operation. METHODDEF int dummy_consume_data (j_decompress_ptr cinfo) { return JPEG_SUSPENDED; // Always indicate nothing was done } #ifdef D_MULTISCAN_FILES_SUPPORTED // * 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. METHODDEF int consume_data (j_decompress_ptr cinfo) { my_coef_ptr coef = (my_coef_ptr) cinfo->coef; JDIMENSION MCU_col_num; // index of current MCU within row int blkn, ci, xindex, yindex, yoffset; JDIMENSION start_col; JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN]; JBLOCKROW buffer_ptr; jpeg_component_info *compptr; // Align the virtual buffers for the components used in this scan. for (ci = 0; ci < cinfo->comps_in_scan; ci++) { compptr = cinfo->cur_comp_info[ci]; buffer[ci] = (*cinfo->mem->access_virt_barray) ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index], cinfo->input_iMCU_row * compptr->v_samp_factor, (JDIMENSION) compptr->v_samp_factor, TRUE); // 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 (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row; yoffset++) { for (MCU_col_num = coef->MCU_ctr; MCU_col_num < cinfo->MCUs_per_row; MCU_col_num++) { // Construct list of pointers to DCT blocks belonging to this MCU blkn = 0; // index of current DCT block within MCU for (ci = 0; ci < cinfo->comps_in_scan; ci++) { compptr = cinfo->cur_comp_info[ci]; start_col = MCU_col_num * compptr->MCU_width; for (yindex = 0; yindex < compptr->MCU_height; yindex++) { buffer_ptr = buffer[ci][yindex+yoffset] + start_col; for (xindex = 0; xindex < compptr->MCU_width; xindex++) { coef->MCU_buffer[blkn++] = buffer_ptr++; } } } // Try to fetch the MCU. if (! (*cinfo->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 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(cinfo); return JPEG_ROW_COMPLETED; } // Completed the scan (*cinfo->inputctl->finish_input_pass) (cinfo); return JPEG_SCAN_COMPLETED; } // * Decompress and return some data in the multi-pass case. // * Always attempts to emit one fully interleaved MCU row ("iMCU" row). // * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED. // * // * NB: output_buf contains a plane for each component in image. METHODDEF int decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf) { my_coef_ptr coef = (my_coef_ptr) cinfo->coef; JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; JDIMENSION block_num; int ci, block_row, block_rows; JBLOCKARRAY buffer; JBLOCKROW buffer_ptr; JSAMPARRAY output_ptr; JDIMENSION output_col; jpeg_component_info *compptr; inverse_DCT_method_ptr inverse_DCT; // Force some input to be done if we are getting ahead of the input. while (cinfo->input_scan_number < cinfo->output_scan_number || (cinfo->input_scan_number == cinfo->output_scan_number && cinfo->input_iMCU_row <= cinfo->output_iMCU_row)) { if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED) return JPEG_SUSPENDED; } // OK, output from the virtual arrays. for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; ci++, compptr++) { // Don't bother to IDCT an uninteresting component. if (! compptr->component_needed) continue; // Align the virtual buffer for this component. buffer = (*cinfo->mem->access_virt_barray) ((j_common_ptr) cinfo, coef->whole_image[ci], cinfo->output_iMCU_row * compptr->v_samp_factor, (JDIMENSION) compptr->v_samp_factor, FALSE); // Count non-dummy DCT block rows in this iMCU row. if (cinfo->output_iMCU_row < last_iMCU_row) block_rows = compptr->v_samp_factor; else { // NB: can't use last_row_height here; it is input-side-dependent! block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor); if (block_rows == 0) block_rows = compptr->v_samp_factor; } inverse_DCT = cinfo->idct->inverse_DCT[ci]; output_ptr = output_buf[ci]; // Loop over all DCT blocks to be processed. for (block_row = 0; block_row < block_rows; block_row++) { buffer_ptr = buffer[block_row]; output_col = 0; for (block_num = 0; block_num < compptr->width_in_blocks; block_num++) { (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) buffer_ptr, output_ptr, output_col); buffer_ptr++; output_col += compptr->DCT_scaled_size; } output_ptr += compptr->DCT_scaled_size; } } if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows) return JPEG_ROW_COMPLETED; return JPEG_SCAN_COMPLETED; } #endif // D_MULTISCAN_FILES_SUPPORTED #ifdef BLOCK_SMOOTHING_SUPPORTED // * This code applies interblock smoothing as described by section K.8 // * of the JPEG standard: the first 5 AC coefficients are estimated from // * the DC values of a DCT block and its 8 neighboring blocks. // * We apply smoothing only for progressive JPEG decoding, and only if // * the coefficients it can estimate are not yet known to full precision. // * Determine whether block smoothing is applicable and safe. // * We also latch the current states of the coef_bits[] entries for the // * AC coefficients; otherwise, if the input side of the decompressor // * advances into a new scan, we might think the coefficients are known // * more accurately than they really are. LOCAL boolean smoothing_ok (j_decompress_ptr cinfo) { my_coef_ptr coef = (my_coef_ptr) cinfo->coef; boolean smoothing_useful = FALSE; int ci, coefi; jpeg_component_info *compptr; JQUANT_TBL * qtable; int * coef_bits; int * coef_bits_latch; if (! cinfo->progressive_mode || cinfo->coef_bits == NULL) return FALSE; // Allocate latch area if not already done if (coef->coef_bits_latch == NULL) coef->coef_bits_latch = (int *) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, cinfo->num_components * (SAVED_COEFS * SIZEOF(int))); coef_bits_latch = coef->coef_bits_latch; for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; ci++, compptr++) { // All components' quantization values must already be latched. if ((qtable = compptr->quant_table) == NULL) return FALSE; // Verify DC & first 5 AC quantizers are nonzero to avoid zero-divide. for (coefi = 0; coefi <= 5; coefi++) { if (qtable->quantval[coefi] == 0) return FALSE; } // DC values must be at least partly known for all components. coef_bits = cinfo->coef_bits[ci]; if (coef_bits[0] < 0) return FALSE; // Block smoothing is helpful if some AC coefficients remain inaccurate. for (coefi = 1; coefi <= 5; coefi++) { coef_bits_latch[coefi] = coef_bits[coefi]; if (coef_bits[coefi] != 0) smoothing_useful = TRUE; } coef_bits_latch += SAVED_COEFS; } return smoothing_useful; } // * Variant of decompress_data for use when doing block smoothing. METHODDEF int decompress_smooth_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf) { my_coef_ptr coef = (my_coef_ptr) cinfo->coef; JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; JDIMENSION block_num, last_block_column; int ci, block_row, block_rows, access_rows; JBLOCKARRAY buffer; JBLOCKROW buffer_ptr, prev_block_row, next_block_row; JSAMPARRAY output_ptr; JDIMENSION output_col; jpeg_component_info *compptr; inverse_DCT_method_ptr inverse_DCT; boolean first_row, last_row; JBLOCK workspace; int *coef_bits; JQUANT_TBL *quanttbl; INT32 Q00,Q01,Q02,Q10,Q11,Q20, num; int DC1,DC2,DC3,DC4,DC5,DC6,DC7,DC8,DC9; int Al, pred; // Force some input to be done if we are getting ahead of the input. while (cinfo->input_scan_number <= cinfo->output_scan_number && ! cinfo->inputctl->eoi_reached) { if (cinfo->input_scan_number == cinfo->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. JDIMENSION delta = (cinfo->Ss == 0) ? 1 : 0; if (cinfo->input_iMCU_row > cinfo->output_iMCU_row+delta) break; } if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED) return JPEG_SUSPENDED; } // OK, output from the virtual arrays. for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; ci++, compptr++) { // Don't bother to IDCT an uninteresting component. if (! compptr->component_needed) continue; // Count non-dummy DCT block rows in this iMCU row. if (cinfo->output_iMCU_row < last_iMCU_row) { block_rows = compptr->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 = (int) (compptr->height_in_blocks % compptr->v_samp_factor); if (block_rows == 0) block_rows = compptr->v_samp_factor; access_rows = block_rows; // this iMCU row only last_row = TRUE; } // Align the virtual buffer for this component. if (cinfo->output_iMCU_row > 0) { access_rows += compptr->v_samp_factor; // prior iMCU row too buffer = (*cinfo->mem->access_virt_barray) ((j_common_ptr) cinfo, coef->whole_image[ci], (cinfo->output_iMCU_row - 1) * compptr->v_samp_factor, (JDIMENSION) access_rows, FALSE); buffer += compptr->v_samp_factor; // point to current iMCU row first_row = FALSE; } else { buffer = (*cinfo->mem->access_virt_barray) ((j_common_ptr) cinfo, coef->whole_image[ci], (JDIMENSION) 0, (JDIMENSION) access_rows, FALSE); first_row = TRUE; } // Fetch component-dependent info coef_bits = coef->coef_bits_latch + (ci * SAVED_COEFS); quanttbl = compptr->quant_table; Q00 = quanttbl->quantval[0]; Q01 = quanttbl->quantval[1]; Q10 = quanttbl->quantval[2]; Q20 = quanttbl->quantval[3]; Q11 = quanttbl->quantval[4]; Q02 = quanttbl->quantval[5]; inverse_DCT = cinfo->idct->inverse_DCT[ci]; output_ptr = output_buf[ci]; // Loop over all DCT blocks to be processed. for (block_row = 0; block_row < block_rows; block_row++) { buffer_ptr = buffer[block_row]; if (first_row && block_row == 0) prev_block_row = buffer_ptr; else prev_block_row = buffer[block_row-1]; if (last_row && block_row == block_rows-1) next_block_row = buffer_ptr; else next_block_row = buffer[block_row+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. DC1 = DC2 = DC3 = (int) prev_block_row[0][0]; DC4 = DC5 = DC6 = (int) buffer_ptr[0][0]; DC7 = DC8 = DC9 = (int) next_block_row[0][0]; output_col = 0; last_block_column = compptr->width_in_blocks - 1; for (block_num = 0; block_num <= last_block_column; block_num++) { // 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< 0 && pred >= (1<= 0) { pred = (int) (((Q10<<7) + num) / (Q10<<8)); if (Al > 0 && pred >= (1< 0 && pred >= (1<= 0) { pred = (int) (((Q20<<7) + num) / (Q20<<8)); if (Al > 0 && pred >= (1< 0 && pred >= (1<= 0) { pred = (int) (((Q11<<7) + num) / (Q11<<8)); if (Al > 0 && pred >= (1< 0 && pred >= (1<= 0) { pred = (int) (((Q02<<7) + num) / (Q02<<8)); if (Al > 0 && pred >= (1< 0 && pred >= (1<DCT_scaled_size; } output_ptr += compptr->DCT_scaled_size; } } if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows) return JPEG_ROW_COMPLETED; return JPEG_SCAN_COMPLETED; } #endif // BLOCK_SMOOTHING_SUPPORTED // * Initialize coefficient buffer controller. GLOBAL void jinit_d_coef_controller (j_decompress_ptr cinfo, boolean need_full_buffer) { my_coef_ptr coef; coef = (my_coef_ptr) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, SIZEOF(my_coef_controller)); cinfo->coef = (struct jpeg_d_coef_controller *) coef; coef->pub.start_input_pass = start_input_pass; coef->pub.start_output_pass = start_output_pass; #ifdef BLOCK_SMOOTHING_SUPPORTED coef->coef_bits_latch = NULL; #endif // Create the coefficient buffer. if (need_full_buffer) { #ifdef D_MULTISCAN_FILES_SUPPORTED // Allocate a full-image virtual array for each component, // padded to a multiple of samp_factor DCT blocks in each direction. // Note we ask for a pre-zeroed array. int ci, access_rows; jpeg_component_info *compptr; for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; ci++, compptr++) { access_rows = compptr->v_samp_factor; #ifdef BLOCK_SMOOTHING_SUPPORTED // If block smoothing could be used, need a bigger window if (cinfo->progressive_mode) access_rows *= 3; #endif coef->whole_image[ci] = (*cinfo->mem->request_virt_barray) ((j_common_ptr) cinfo, JPOOL_IMAGE, TRUE, (JDIMENSION) jround_up((LONG) compptr->width_in_blocks, (LONG) compptr->h_samp_factor), (JDIMENSION) jround_up((LONG) compptr->height_in_blocks, (LONG) compptr->v_samp_factor), (JDIMENSION) access_rows); } coef->pub.consume_data = consume_data; coef->pub.decompress_data = decompress_data; coef->pub.coef_arrays = coef->whole_image; // link to virtual arrays #else ERREXIT(cinfo, JERR_NOT_COMPILED); #endif } else { // We only need a single-MCU buffer. JBLOCKROW buffer; int i; buffer = (JBLOCKROW) (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE, D_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK)); for (i = 0; i < D_MAX_BLOCKS_IN_MCU; i++) { coef->MCU_buffer[i] = buffer + i; } coef->pub.consume_data = dummy_consume_data; coef->pub.decompress_data = decompress_onepass; coef->pub.coef_arrays = NULL; // flag for no virtual arrays } }