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Diffstat (limited to 'src/libjpeg/jccoefct.c')
| -rw-r--r-- | src/libjpeg/jccoefct.c | 449 |
1 files changed, 449 insertions, 0 deletions
diff --git a/src/libjpeg/jccoefct.c b/src/libjpeg/jccoefct.c new file mode 100644 index 0000000..1963ddb --- /dev/null +++ b/src/libjpeg/jccoefct.c @@ -0,0 +1,449 @@ +/* + * 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 */ + } +} |