jdpostct.c - third_party/libjpeg-turbo - Git at Google

 /*
  * jdpostct.c
  *
  * This file was part of the Independent JPEG Group's software:
  * Copyright (C) 1994-1996, Thomas G. Lane.
  * It was modified by The libjpeg-turbo Project to include only code relevant
  * to libjpeg-turbo.
  * For conditions of distribution and use, see the accompanying README file.
  *
  * This file contains the decompression postprocessing controller.
  * This controller manages the upsampling, color conversion, and color
  * quantization/reduction steps; specifically, it controls the buffering
  * between upsample/color conversion and color quantization/reduction.
  *
  * If no color quantization/reduction is required, then this module has no
  * work to do, and it just hands off to the upsample/color conversion code.
  * An integrated upsample/convert/quantize process would replace this module
  * entirely.
  */

 #define JPEG_INTERNALS
 #include "jinclude.h"
 #include "jpeglib.h"


 /* Private buffer controller object */

 typedef struct {
   struct jpeg_d_post_controller pub; /* public fields */

   /* Color quantization source buffer: this holds output data from
    * the upsample/color conversion step to be passed to the quantizer.
    * For two-pass color quantization, we need a full-image buffer;
    * for one-pass operation, a strip buffer is sufficient.
    */
   jvirt_sarray_ptr whole_image; /* virtual array, or NULL if one-pass */
   JSAMPARRAY buffer;            /* strip buffer, or current strip of virtual */
   JDIMENSION strip_height;      /* buffer size in rows */
   /* for two-pass mode only: */
   JDIMENSION starting_row;      /* row # of first row in current strip */
   JDIMENSION next_row;          /* index of next row to fill/empty in strip */
 } my_post_controller;

 typedef my_post_controller * my_post_ptr;


 /* Forward declarations */
 METHODDEF(void) post_process_1pass
         (j_decompress_ptr cinfo, JSAMPIMAGE input_buf,
          JDIMENSION *in_row_group_ctr, JDIMENSION in_row_groups_avail,
          JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
          JDIMENSION out_rows_avail);
 #ifdef QUANT_2PASS_SUPPORTED
 METHODDEF(void) post_process_prepass
         (j_decompress_ptr cinfo, JSAMPIMAGE input_buf,
          JDIMENSION *in_row_group_ctr, JDIMENSION in_row_groups_avail,
          JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
          JDIMENSION out_rows_avail);
 METHODDEF(void) post_process_2pass
         (j_decompress_ptr cinfo, JSAMPIMAGE input_buf,
          JDIMENSION *in_row_group_ctr, JDIMENSION in_row_groups_avail,
          JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
          JDIMENSION out_rows_avail);
 #endif


 /*
  * Initialize for a processing pass.
  */

 METHODDEF(void)
 start_pass_dpost (j_decompress_ptr cinfo, J_BUF_MODE pass_mode)
 {
   my_post_ptr post = (my_post_ptr) cinfo->post;

   switch (pass_mode) {
   case JBUF_PASS_THRU:
     if (cinfo->quantize_colors) {
       /* Single-pass processing with color quantization. */
       post->pub.post_process_data = post_process_1pass;
       /* We could be doing buffered-image output before starting a 2-pass
        * color quantization; in that case, jinit_d_post_controller did not
        * allocate a strip buffer.  Use the virtual-array buffer as workspace.
        */
       if (post->buffer == NULL) {
         post->buffer = (*cinfo->mem->access_virt_sarray)
           ((j_common_ptr) cinfo, post->whole_image,
            (JDIMENSION) 0, post->strip_height, TRUE);
       }
     } else {
       /* For single-pass processing without color quantization,
        * I have no work to do; just call the upsampler directly.
        */
       post->pub.post_process_data = cinfo->upsample->upsample;
     }
     break;
 #ifdef QUANT_2PASS_SUPPORTED
   case JBUF_SAVE_AND_PASS:
     /* First pass of 2-pass quantization */
     if (post->whole_image == NULL)
       ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
     post->pub.post_process_data = post_process_prepass;
     break;
   case JBUF_CRANK_DEST:
     /* Second pass of 2-pass quantization */
     if (post->whole_image == NULL)
       ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
     post->pub.post_process_data = post_process_2pass;
     break;
 #endif /* QUANT_2PASS_SUPPORTED */
   default:
     ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
     break;
   }
   post->starting_row = post->next_row = 0;
 }


 /*
  * Process some data in the one-pass (strip buffer) case.
  * This is used for color precision reduction as well as one-pass quantization.
  */

 METHODDEF(void)
 post_process_1pass (j_decompress_ptr cinfo,
                     JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
                     JDIMENSION in_row_groups_avail,
                     JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
                     JDIMENSION out_rows_avail)
 {
   my_post_ptr post = (my_post_ptr) cinfo->post;
   JDIMENSION num_rows, max_rows;

   /* Fill the buffer, but not more than what we can dump out in one go. */
   /* Note we rely on the upsampler to detect bottom of image. */
   max_rows = out_rows_avail - *out_row_ctr;
   if (max_rows > post->strip_height)
     max_rows = post->strip_height;
   num_rows = 0;
   (*cinfo->upsample->upsample) (cinfo,
                 input_buf, in_row_group_ctr, in_row_groups_avail,
                 post->buffer, &num_rows, max_rows);
   /* Quantize and emit data. */
   (*cinfo->cquantize->color_quantize) (cinfo,
                 post->buffer, output_buf + *out_row_ctr, (int) num_rows);
   *out_row_ctr += num_rows;
 }


 #ifdef QUANT_2PASS_SUPPORTED

 /*
  * Process some data in the first pass of 2-pass quantization.
  */

 METHODDEF(void)
 post_process_prepass (j_decompress_ptr cinfo,
                       JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
                       JDIMENSION in_row_groups_avail,
                       JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
                       JDIMENSION out_rows_avail)
 {
   my_post_ptr post = (my_post_ptr) cinfo->post;
   JDIMENSION old_next_row, num_rows;

   /* Reposition virtual buffer if at start of strip. */
   if (post->next_row == 0) {
     post->buffer = (*cinfo->mem->access_virt_sarray)
         ((j_common_ptr) cinfo, post->whole_image,
          post->starting_row, post->strip_height, TRUE);
   }

   /* Upsample some data (up to a strip height's worth). */
   old_next_row = post->next_row;
   (*cinfo->upsample->upsample) (cinfo,
                 input_buf, in_row_group_ctr, in_row_groups_avail,
                 post->buffer, &post->next_row, post->strip_height);

   /* Allow quantizer to scan new data.  No data is emitted, */
   /* but we advance out_row_ctr so outer loop can tell when we're done. */
   if (post->next_row > old_next_row) {
     num_rows = post->next_row - old_next_row;
     (*cinfo->cquantize->color_quantize) (cinfo, post->buffer + old_next_row,
                                          (JSAMPARRAY) NULL, (int) num_rows);
     *out_row_ctr += num_rows;
   }

   /* Advance if we filled the strip. */
   if (post->next_row >= post->strip_height) {
     post->starting_row += post->strip_height;
     post->next_row = 0;
   }
 }


 /*
  * Process some data in the second pass of 2-pass quantization.
  */

 METHODDEF(void)
 post_process_2pass (j_decompress_ptr cinfo,
                     JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
                     JDIMENSION in_row_groups_avail,
                     JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
                     JDIMENSION out_rows_avail)
 {
   my_post_ptr post = (my_post_ptr) cinfo->post;
   JDIMENSION num_rows, max_rows;

   /* Reposition virtual buffer if at start of strip. */
   if (post->next_row == 0) {
     post->buffer = (*cinfo->mem->access_virt_sarray)
         ((j_common_ptr) cinfo, post->whole_image,
          post->starting_row, post->strip_height, FALSE);
   }

   /* Determine number of rows to emit. */
   num_rows = post->strip_height - post->next_row; /* available in strip */
   max_rows = out_rows_avail - *out_row_ctr; /* available in output area */
   if (num_rows > max_rows)
     num_rows = max_rows;
   /* We have to check bottom of image here, can't depend on upsampler. */
   max_rows = cinfo->output_height - post->starting_row;
   if (num_rows > max_rows)
     num_rows = max_rows;

   /* Quantize and emit data. */
   (*cinfo->cquantize->color_quantize) (cinfo,
                 post->buffer + post->next_row, output_buf + *out_row_ctr,
                 (int) num_rows);
   *out_row_ctr += num_rows;

   /* Advance if we filled the strip. */
   post->next_row += num_rows;
   if (post->next_row >= post->strip_height) {
     post->starting_row += post->strip_height;
     post->next_row = 0;
   }
 }

 #endif /* QUANT_2PASS_SUPPORTED */


 /*
  * Initialize postprocessing controller.
  */

 GLOBAL(void)
 jinit_d_post_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
 {
   my_post_ptr post;

   post = (my_post_ptr)
     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
                                 sizeof(my_post_controller));
   cinfo->post = (struct jpeg_d_post_controller *) post;
   post->pub.start_pass = start_pass_dpost;
   post->whole_image = NULL;     /* flag for no virtual arrays */
   post->buffer = NULL;          /* flag for no strip buffer */

   /* Create the quantization buffer, if needed */
   if (cinfo->quantize_colors) {
     /* The buffer strip height is max_v_samp_factor, which is typically
      * an efficient number of rows for upsampling to return.
      * (In the presence of output rescaling, we might want to be smarter?)
      */
     post->strip_height = (JDIMENSION) cinfo->max_v_samp_factor;
     if (need_full_buffer) {
       /* Two-pass color quantization: need full-image storage. */
       /* We round up the number of rows to a multiple of the strip height. */
 #ifdef QUANT_2PASS_SUPPORTED
       post->whole_image = (*cinfo->mem->request_virt_sarray)
         ((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
          cinfo->output_width * cinfo->out_color_components,
          (JDIMENSION) jround_up((long) cinfo->output_height,
                                 (long) post->strip_height),
          post->strip_height);
 #else
       ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
 #endif /* QUANT_2PASS_SUPPORTED */
     } else {
       /* One-pass color quantization: just make a strip buffer. */
       post->buffer = (*cinfo->mem->alloc_sarray)
         ((j_common_ptr) cinfo, JPOOL_IMAGE,
          cinfo->output_width * cinfo->out_color_components,
          post->strip_height);
     }
   }
 }
	/*
	* jdpostct.c
	*
	* This file was part of the Independent JPEG Group's software:
	* Copyright (C) 1994-1996, Thomas G. Lane.
	* It was modified by The libjpeg-turbo Project to include only code relevant
	* to libjpeg-turbo.
	* For conditions of distribution and use, see the accompanying README file.
	*
	* This file contains the decompression postprocessing controller.
	* This controller manages the upsampling, color conversion, and color
	* quantization/reduction steps; specifically, it controls the buffering
	* between upsample/color conversion and color quantization/reduction.
	*
	* If no color quantization/reduction is required, then this module has no
	* work to do, and it just hands off to the upsample/color conversion code.
	* An integrated upsample/convert/quantize process would replace this module
	* entirely.
	*/

	#define JPEG_INTERNALS
	#include "jinclude.h"
	#include "jpeglib.h"


	/* Private buffer controller object */

	typedef struct {
	struct jpeg_d_post_controller pub; /* public fields */

	/* Color quantization source buffer: this holds output data from
	* the upsample/color conversion step to be passed to the quantizer.
	* For two-pass color quantization, we need a full-image buffer;
	* for one-pass operation, a strip buffer is sufficient.
	*/
	jvirt_sarray_ptr whole_image; /* virtual array, or NULL if one-pass */
	JSAMPARRAY buffer; /* strip buffer, or current strip of virtual */
	JDIMENSION strip_height; /* buffer size in rows */
	/* for two-pass mode only: */
	JDIMENSION starting_row; /* row # of first row in current strip */
	JDIMENSION next_row; /* index of next row to fill/empty in strip */
	} my_post_controller;

	typedef my_post_controller * my_post_ptr;


	/* Forward declarations */
	METHODDEF(void) post_process_1pass
	(j_decompress_ptr cinfo, JSAMPIMAGE input_buf,
	JDIMENSION *in_row_group_ctr, JDIMENSION in_row_groups_avail,
	JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
	JDIMENSION out_rows_avail);
	#ifdef QUANT_2PASS_SUPPORTED
	METHODDEF(void) post_process_prepass
	(j_decompress_ptr cinfo, JSAMPIMAGE input_buf,
	JDIMENSION *in_row_group_ctr, JDIMENSION in_row_groups_avail,
	JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
	JDIMENSION out_rows_avail);
	METHODDEF(void) post_process_2pass
	(j_decompress_ptr cinfo, JSAMPIMAGE input_buf,
	JDIMENSION *in_row_group_ctr, JDIMENSION in_row_groups_avail,
	JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
	JDIMENSION out_rows_avail);
	#endif


	/*
	* Initialize for a processing pass.
	*/

	METHODDEF(void)
	start_pass_dpost (j_decompress_ptr cinfo, J_BUF_MODE pass_mode)
	{
	my_post_ptr post = (my_post_ptr) cinfo->post;

	switch (pass_mode) {
	case JBUF_PASS_THRU:
	if (cinfo->quantize_colors) {
	/* Single-pass processing with color quantization. */
	post->pub.post_process_data = post_process_1pass;
	/* We could be doing buffered-image output before starting a 2-pass
	* color quantization; in that case, jinit_d_post_controller did not
	* allocate a strip buffer. Use the virtual-array buffer as workspace.
	*/
	if (post->buffer == NULL) {
	post->buffer = (*cinfo->mem->access_virt_sarray)
	((j_common_ptr) cinfo, post->whole_image,
	(JDIMENSION) 0, post->strip_height, TRUE);
	}
	} else {
	/* For single-pass processing without color quantization,
	* I have no work to do; just call the upsampler directly.
	*/
	post->pub.post_process_data = cinfo->upsample->upsample;
	}
	break;
	#ifdef QUANT_2PASS_SUPPORTED
	case JBUF_SAVE_AND_PASS:
	/* First pass of 2-pass quantization */
	if (post->whole_image == NULL)
	ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
	post->pub.post_process_data = post_process_prepass;
	break;
	case JBUF_CRANK_DEST:
	/* Second pass of 2-pass quantization */
	if (post->whole_image == NULL)
	ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
	post->pub.post_process_data = post_process_2pass;
	break;
	#endif /* QUANT_2PASS_SUPPORTED */
	default:
	ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
	break;
	}
	post->starting_row = post->next_row = 0;
	}


	/*
	* Process some data in the one-pass (strip buffer) case.
	* This is used for color precision reduction as well as one-pass quantization.
	*/

	METHODDEF(void)
	post_process_1pass (j_decompress_ptr cinfo,
	JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
	JDIMENSION in_row_groups_avail,
	JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
	JDIMENSION out_rows_avail)
	{
	my_post_ptr post = (my_post_ptr) cinfo->post;
	JDIMENSION num_rows, max_rows;

	/* Fill the buffer, but not more than what we can dump out in one go. */
	/* Note we rely on the upsampler to detect bottom of image. */
	max_rows = out_rows_avail - *out_row_ctr;
	if (max_rows > post->strip_height)
	max_rows = post->strip_height;
	num_rows = 0;
	(*cinfo->upsample->upsample) (cinfo,
	input_buf, in_row_group_ctr, in_row_groups_avail,
	post->buffer, &num_rows, max_rows);
	/* Quantize and emit data. */
	(*cinfo->cquantize->color_quantize) (cinfo,
	post->buffer, output_buf + *out_row_ctr, (int) num_rows);
	*out_row_ctr += num_rows;
	}


	#ifdef QUANT_2PASS_SUPPORTED

	/*
	* Process some data in the first pass of 2-pass quantization.
	*/

	METHODDEF(void)
	post_process_prepass (j_decompress_ptr cinfo,
	JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
	JDIMENSION in_row_groups_avail,
	JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
	JDIMENSION out_rows_avail)
	{
	my_post_ptr post = (my_post_ptr) cinfo->post;
	JDIMENSION old_next_row, num_rows;

	/* Reposition virtual buffer if at start of strip. */
	if (post->next_row == 0) {
	post->buffer = (*cinfo->mem->access_virt_sarray)
	((j_common_ptr) cinfo, post->whole_image,
	post->starting_row, post->strip_height, TRUE);
	}

	/* Upsample some data (up to a strip height's worth). */
	old_next_row = post->next_row;
	(*cinfo->upsample->upsample) (cinfo,
	input_buf, in_row_group_ctr, in_row_groups_avail,
	post->buffer, &post->next_row, post->strip_height);

	/* Allow quantizer to scan new data. No data is emitted, */
	/* but we advance out_row_ctr so outer loop can tell when we're done. */
	if (post->next_row > old_next_row) {
	num_rows = post->next_row - old_next_row;
	(*cinfo->cquantize->color_quantize) (cinfo, post->buffer + old_next_row,
	(JSAMPARRAY) NULL, (int) num_rows);
	*out_row_ctr += num_rows;
	}

	/* Advance if we filled the strip. */
	if (post->next_row >= post->strip_height) {
	post->starting_row += post->strip_height;
	post->next_row = 0;
	}
	}


	/*
	* Process some data in the second pass of 2-pass quantization.
	*/

	METHODDEF(void)
	post_process_2pass (j_decompress_ptr cinfo,
	JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
	JDIMENSION in_row_groups_avail,
	JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
	JDIMENSION out_rows_avail)
	{
	my_post_ptr post = (my_post_ptr) cinfo->post;
	JDIMENSION num_rows, max_rows;

	/* Reposition virtual buffer if at start of strip. */
	if (post->next_row == 0) {
	post->buffer = (*cinfo->mem->access_virt_sarray)
	((j_common_ptr) cinfo, post->whole_image,
	post->starting_row, post->strip_height, FALSE);
	}

	/* Determine number of rows to emit. */
	num_rows = post->strip_height - post->next_row; /* available in strip */
	max_rows = out_rows_avail - out_row_ctr; / available in output area */
	if (num_rows > max_rows)
	num_rows = max_rows;
	/* We have to check bottom of image here, can't depend on upsampler. */
	max_rows = cinfo->output_height - post->starting_row;
	if (num_rows > max_rows)
	num_rows = max_rows;

	/* Quantize and emit data. */
	(*cinfo->cquantize->color_quantize) (cinfo,
	post->buffer + post->next_row, output_buf + *out_row_ctr,
	(int) num_rows);
	*out_row_ctr += num_rows;

	/* Advance if we filled the strip. */
	post->next_row += num_rows;
	if (post->next_row >= post->strip_height) {
	post->starting_row += post->strip_height;
	post->next_row = 0;
	}
	}

	#endif /* QUANT_2PASS_SUPPORTED */


	/*
	* Initialize postprocessing controller.
	*/

	GLOBAL(void)
	jinit_d_post_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
	{
	my_post_ptr post;

	post = (my_post_ptr)
	(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
	sizeof(my_post_controller));
	cinfo->post = (struct jpeg_d_post_controller *) post;
	post->pub.start_pass = start_pass_dpost;
	post->whole_image = NULL; /* flag for no virtual arrays */
	post->buffer = NULL; /* flag for no strip buffer */

	/* Create the quantization buffer, if needed */
	if (cinfo->quantize_colors) {
	/* The buffer strip height is max_v_samp_factor, which is typically
	* an efficient number of rows for upsampling to return.
	* (In the presence of output rescaling, we might want to be smarter?)
	*/
	post->strip_height = (JDIMENSION) cinfo->max_v_samp_factor;
	if (need_full_buffer) {
	/* Two-pass color quantization: need full-image storage. */
	/* We round up the number of rows to a multiple of the strip height. */
	#ifdef QUANT_2PASS_SUPPORTED
	post->whole_image = (*cinfo->mem->request_virt_sarray)
	((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
	cinfo->output_width * cinfo->out_color_components,
	(JDIMENSION) jround_up((long) cinfo->output_height,
	(long) post->strip_height),
	post->strip_height);
	#else
	ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
	#endif /* QUANT_2PASS_SUPPORTED */
	} else {
	/* One-pass color quantization: just make a strip buffer. */
	post->buffer = (*cinfo->mem->alloc_sarray)
	((j_common_ptr) cinfo, JPOOL_IMAGE,
	cinfo->output_width * cinfo->out_color_components,
	post->strip_height);
	}
	}
	}