| /* |
| * jccoefct.c |
| * |
| * Copyright (C) 1994-1997, 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 compression. |
| * This controller is the top level of the JPEG compressor proper. |
| * The coefficient buffer lies between forward-DCT and entropy encoding steps. |
| */ |
| |
| #define JPEG_INTERNALS |
| #include "jinclude.h" |
| #include "jpeglib.h" |
| |
| |
| /* We use a full-image coefficient buffer when doing Huffman optimization, |
| * and also for writing multiple-scan JPEG files. In all cases, the DCT |
| * step is run during the first pass, and subsequent passes need only read |
| * the buffered coefficients. |
| */ |
| #ifdef ENTROPY_OPT_SUPPORTED |
| #define FULL_COEF_BUFFER_SUPPORTED |
| #else |
| #ifdef C_MULTISCAN_FILES_SUPPORTED |
| #define FULL_COEF_BUFFER_SUPPORTED |
| #endif |
| #endif |
| |
| |
| /* Private buffer controller object */ |
| |
| typedef struct { |
| struct jpeg_c_coef_controller pub; /* public fields */ |
| |
| JDIMENSION iMCU_row_num; /* iMCU row # within image */ |
| 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 */ |
| |
| /* For single-pass compression, it's sufficient to buffer just one MCU |
| * (although this may prove a bit slow in practice). We allocate a |
| * workspace of C_MAX_BLOCKS_IN_MCU coefficient blocks, and reuse it for each |
| * MCU constructed and sent. (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. |
| */ |
| JBLOCKROW MCU_buffer[C_MAX_BLOCKS_IN_MCU]; |
| |
| /* In multi-pass modes, we need a virtual block array for each component. */ |
| jvirt_barray_ptr whole_image[MAX_COMPONENTS]; |
| } my_coef_controller; |
| |
| typedef my_coef_controller * my_coef_ptr; |
| |
| |
| /* Forward declarations */ |
| METHODDEF(boolean) compress_data |
| JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf)); |
| #ifdef FULL_COEF_BUFFER_SUPPORTED |
| METHODDEF(boolean) compress_first_pass |
| JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf)); |
| METHODDEF(boolean) compress_output |
| JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf)); |
| #endif |
| |
| |
| LOCAL(void) |
| start_iMCU_row (j_compress_ptr cinfo) |
| /* Reset within-iMCU-row counters for a new row */ |
| { |
| 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 (coef->iMCU_row_num < (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 a processing pass. |
| */ |
| |
| METHODDEF(void) |
| start_pass_coef (j_compress_ptr cinfo, J_BUF_MODE pass_mode) |
| { |
| my_coef_ptr coef = (my_coef_ptr) cinfo->coef; |
| |
| coef->iMCU_row_num = 0; |
| start_iMCU_row(cinfo); |
| |
| switch (pass_mode) { |
| case JBUF_PASS_THRU: |
| if (coef->whole_image[0] != NULL) |
| ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); |
| coef->pub.compress_data = compress_data; |
| break; |
| #ifdef FULL_COEF_BUFFER_SUPPORTED |
| case JBUF_SAVE_AND_PASS: |
| if (coef->whole_image[0] == NULL) |
| ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); |
| coef->pub.compress_data = compress_first_pass; |
| break; |
| case JBUF_CRANK_DEST: |
| if (coef->whole_image[0] == NULL) |
| ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); |
| coef->pub.compress_data = compress_output; |
| break; |
| #endif |
| default: |
| ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); |
| break; |
| } |
| } |
| |
| |
| /* |
| * Process some data in the single-pass case. |
| * We process the equivalent of one fully interleaved MCU row ("iMCU" row) |
| * per call, ie, v_samp_factor block rows for each component in the image. |
| * Returns TRUE if the iMCU row is completed, FALSE if suspended. |
| * |
| * NB: input_buf contains a plane for each component in image, |
| * which we index according to the component's SOF position. |
| */ |
| |
| METHODDEF(boolean) |
| compress_data (j_compress_ptr cinfo, JSAMPIMAGE input_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, bi, ci, yindex, yoffset, blockcnt; |
| JDIMENSION ypos, xpos; |
| jpeg_component_info *compptr; |
| |
| /* Loop to write 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++) { |
| /* Determine where data comes from in input_buf and do the DCT thing. |
| * Each call on forward_DCT processes a horizontal row of DCT blocks |
| * as wide as an MCU; we rely on having allocated the MCU_buffer[] blocks |
| * sequentially. Dummy blocks at the right or bottom edge are filled in |
| * specially. The data in them does not matter for image reconstruction, |
| * so we fill them with values that will encode to the smallest amount of |
| * data, viz: all zeroes in the AC entries, DC entries equal to previous |
| * block's DC value. (Thanks to Thomas Kinsman for this idea.) |
| */ |
| blkn = 0; |
| for (ci = 0; ci < cinfo->comps_in_scan; ci++) { |
| compptr = cinfo->cur_comp_info[ci]; |
| blockcnt = (MCU_col_num < last_MCU_col) ? compptr->MCU_width |
| : compptr->last_col_width; |
| xpos = MCU_col_num * compptr->MCU_sample_width; |
| ypos = yoffset * DCTSIZE; /* ypos == (yoffset+yindex) * DCTSIZE */ |
| for (yindex = 0; yindex < compptr->MCU_height; yindex++) { |
| if (coef->iMCU_row_num < last_iMCU_row || |
| yoffset+yindex < compptr->last_row_height) { |
| (*cinfo->fdct->forward_DCT) (cinfo, compptr, |
| input_buf[compptr->component_index], |
| coef->MCU_buffer[blkn], |
| ypos, xpos, (JDIMENSION) blockcnt); |
| if (blockcnt < compptr->MCU_width) { |
| /* Create some dummy blocks at the right edge of the image. */ |
| jzero_far((void FAR *) coef->MCU_buffer[blkn + blockcnt], |
| (compptr->MCU_width - blockcnt) * SIZEOF(JBLOCK)); |
| for (bi = blockcnt; bi < compptr->MCU_width; bi++) { |
| coef->MCU_buffer[blkn+bi][0][0] = coef->MCU_buffer[blkn+bi-1][0][0]; |
| } |
| } |
| } else { |
| /* Create a row of dummy blocks at the bottom of the image. */ |
| jzero_far((void FAR *) coef->MCU_buffer[blkn], |
| compptr->MCU_width * SIZEOF(JBLOCK)); |
| for (bi = 0; bi < compptr->MCU_width; bi++) { |
| coef->MCU_buffer[blkn+bi][0][0] = coef->MCU_buffer[blkn-1][0][0]; |
| } |
| } |
| blkn += compptr->MCU_width; |
| ypos += DCTSIZE; |
| } |
| } |
| /* Try to write the MCU. In event of a suspension failure, we will |
| * re-DCT the MCU on restart (a bit inefficient, could be fixed...) |
| */ |
| if (! (*cinfo->entropy->encode_mcu) (cinfo, coef->MCU_buffer)) { |
| /* Suspension forced; update state counters and exit */ |
| coef->MCU_vert_offset = yoffset; |
| coef->mcu_ctr = MCU_col_num; |
| return FALSE; |
| } |
| } |
| /* Completed an MCU row, but perhaps not an iMCU row */ |
| coef->mcu_ctr = 0; |
| } |
| /* Completed the iMCU row, advance counters for next one */ |
| coef->iMCU_row_num++; |
| start_iMCU_row(cinfo); |
| return TRUE; |
| } |
| |
| |
| #ifdef FULL_COEF_BUFFER_SUPPORTED |
| |
| /* |
| * Process some data in the first pass of a multi-pass case. |
| * We process the equivalent of one fully interleaved MCU row ("iMCU" row) |
| * per call, ie, v_samp_factor block rows for each component in the image. |
| * This amount of data is read from the source buffer, DCT'd and quantized, |
| * and saved into the virtual arrays. We also generate suitable dummy blocks |
| * as needed at the right and lower edges. (The dummy blocks are constructed |
| * in the virtual arrays, which have been padded appropriately.) This makes |
| * it possible for subsequent passes not to worry about real vs. dummy blocks. |
| * |
| * We must also emit the data to the entropy encoder. This is conveniently |
| * done by calling compress_output() after we've loaded the current strip |
| * of the virtual arrays. |
| * |
| * NB: input_buf contains a plane for each component in image. All |
| * components are DCT'd and loaded into the virtual arrays in this pass. |
| * However, it may be that only a subset of the components are emitted to |
| * the entropy encoder during this first pass; be careful about looking |
| * at the scan-dependent variables (MCU dimensions, etc). |
| */ |
| |
| METHODDEF(boolean) |
| compress_first_pass (j_compress_ptr cinfo, JSAMPIMAGE input_buf) |
| { |
| my_coef_ptr coef = (my_coef_ptr) cinfo->coef; |
| JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; |
| JDIMENSION blocks_across, MCUs_across, MCUindex; |
| int bi, ci, h_samp_factor, block_row, block_rows, ndummy; |
| JCOEF lastDC; |
| jpeg_component_info *compptr; |
| JBLOCKARRAY buffer; |
| JBLOCKROW thisblockrow, lastblockrow; |
| |
| for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; |
| ci++, compptr++) { |
| /* Align the virtual buffer for this component. */ |
| buffer = (*cinfo->mem->access_virt_barray) |
| ((j_common_ptr) cinfo, coef->whole_image[ci], |
| coef->iMCU_row_num * compptr->v_samp_factor, |
| (JDIMENSION) compptr->v_samp_factor, TRUE); |
| /* Count non-dummy DCT block rows in this iMCU row. */ |
| if (coef->iMCU_row_num < last_iMCU_row) |
| block_rows = compptr->v_samp_factor; |
| else { |
| /* NB: can't use last_row_height here, since may not be set! */ |
| block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor); |
| if (block_rows == 0) block_rows = compptr->v_samp_factor; |
| } |
| blocks_across = compptr->width_in_blocks; |
| h_samp_factor = compptr->h_samp_factor; |
| /* Count number of dummy blocks to be added at the right margin. */ |
| ndummy = (int) (blocks_across % h_samp_factor); |
| if (ndummy > 0) |
| ndummy = h_samp_factor - ndummy; |
| /* Perform DCT for all non-dummy blocks in this iMCU row. Each call |
| * on forward_DCT processes a complete horizontal row of DCT blocks. |
| */ |
| for (block_row = 0; block_row < block_rows; block_row++) { |
| thisblockrow = buffer[block_row]; |
| (*cinfo->fdct->forward_DCT) (cinfo, compptr, |
| input_buf[ci], thisblockrow, |
| (JDIMENSION) (block_row * DCTSIZE), |
| (JDIMENSION) 0, blocks_across); |
| if (ndummy > 0) { |
| /* Create dummy blocks at the right edge of the image. */ |
| thisblockrow += blocks_across; /* => first dummy block */ |
| jzero_far((void FAR *) thisblockrow, ndummy * SIZEOF(JBLOCK)); |
| lastDC = thisblockrow[-1][0]; |
| for (bi = 0; bi < ndummy; bi++) { |
| thisblockrow[bi][0] = lastDC; |
| } |
| } |
| } |
| /* If at end of image, create dummy block rows as needed. |
| * The tricky part here is that within each MCU, we want the DC values |
| * of the dummy blocks to match the last real block's DC value. |
| * This squeezes a few more bytes out of the resulting file... |
| */ |
| if (coef->iMCU_row_num == last_iMCU_row) { |
| blocks_across += ndummy; /* include lower right corner */ |
| MCUs_across = blocks_across / h_samp_factor; |
| for (block_row = block_rows; block_row < compptr->v_samp_factor; |
| block_row++) { |
| thisblockrow = buffer[block_row]; |
| lastblockrow = buffer[block_row-1]; |
| jzero_far((void FAR *) thisblockrow, |
| (size_t) (blocks_across * SIZEOF(JBLOCK))); |
| for (MCUindex = 0; MCUindex < MCUs_across; MCUindex++) { |
| lastDC = lastblockrow[h_samp_factor-1][0]; |
| for (bi = 0; bi < h_samp_factor; bi++) { |
| thisblockrow[bi][0] = lastDC; |
| } |
| thisblockrow += h_samp_factor; /* advance to next MCU in row */ |
| lastblockrow += h_samp_factor; |
| } |
| } |
| } |
| } |
| /* NB: compress_output will increment iMCU_row_num if successful. |
| * A suspension return will result in redoing all the work above next time. |
| */ |
| |
| /* Emit data to the entropy encoder, sharing code with subsequent passes */ |
| return compress_output(cinfo, input_buf); |
| } |
| |
| |
| /* |
| * Process some data in subsequent passes of a multi-pass case. |
| * We process the equivalent of one fully interleaved MCU row ("iMCU" row) |
| * per call, ie, v_samp_factor block rows for each component in the scan. |
| * The data is obtained from the virtual arrays and fed to the entropy coder. |
| * Returns TRUE if the iMCU row is completed, FALSE if suspended. |
| * |
| * NB: input_buf is ignored; it is likely to be a NULL pointer. |
| */ |
| |
| METHODDEF(boolean) |
| compress_output (j_compress_ptr cinfo, JSAMPIMAGE input_buf) |
| { |
| 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. |
| * NB: during first pass, this is safe only because the buffers will |
| * already be aligned properly, so jmemmgr.c won't need to do any I/O. |
| */ |
| 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], |
| coef->iMCU_row_num * compptr->v_samp_factor, |
| (JDIMENSION) compptr->v_samp_factor, FALSE); |
| } |
| |
| /* 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 write the MCU. */ |
| if (! (*cinfo->entropy->encode_mcu) (cinfo, coef->MCU_buffer)) { |
| /* Suspension forced; update state counters and exit */ |
| coef->MCU_vert_offset = yoffset; |
| coef->mcu_ctr = MCU_col_num; |
| return FALSE; |
| } |
| } |
| /* Completed an MCU row, but perhaps not an iMCU row */ |
| coef->mcu_ctr = 0; |
| } |
| /* Completed the iMCU row, advance counters for next one */ |
| coef->iMCU_row_num++; |
| start_iMCU_row(cinfo); |
| return TRUE; |
| } |
| |
| #endif /* FULL_COEF_BUFFER_SUPPORTED */ |
| |
| |
| /* |
| * Initialize coefficient buffer controller. |
| */ |
| |
| GLOBAL(void) |
| jinit_c_coef_controller (j_compress_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_c_coef_controller *) coef; |
| coef->pub.start_pass = start_pass_coef; |
| |
| /* Create the coefficient buffer. */ |
| if (need_full_buffer) { |
| #ifdef FULL_COEF_BUFFER_SUPPORTED |
| /* Allocate a full-image virtual array for each component, */ |
| /* padded to a multiple of samp_factor DCT blocks in each direction. */ |
| int ci; |
| jpeg_component_info *compptr; |
| |
| for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; |
| ci++, compptr++) { |
| coef->whole_image[ci] = (*cinfo->mem->request_virt_barray) |
| ((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE, |
| (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) compptr->v_samp_factor); |
| } |
| #else |
| ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); |
| #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, |
| C_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK)); |
| for (i = 0; i < C_MAX_BLOCKS_IN_MCU; i++) { |
| coef->MCU_buffer[i] = buffer + i; |
| } |
| coef->whole_image[0] = NULL; /* flag for no virtual arrays */ |
| } |
| } |
