kc3-lang/libjpeg-turbo/jdtrans.c

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• Hash : 19c791cd
  Author :
  Date : 2018-03-08T10:55:20
  

  Improve code formatting consistency
  
  With rare exceptions ...
  - Always separate line continuation characters by one space from
    preceding code.
  - Always use two-space indentation.  Never use tabs.
  - Always use K&R-style conditional blocks.
  - Always surround operators with spaces, except in raw assembly code.
  - Always put a space after, but not before, a comma.
  - Never put a space between type casts and variables/function calls.
  - Never put a space between the function name and the argument list in
    function declarations and prototypes.
  - Always surround braces ('{' and '}') with spaces.
  - Always surround statements (if, for, else, catch, while, do, switch)
    with spaces.
  - Always attach pointer symbols ('*' and '**') to the variable or
    function name.
  - Always precede pointer symbols ('*' and '**') by a space in type
    casts.
  - Use the MIN() macro from jpegint.h within the libjpeg and TurboJPEG
    API libraries (using min() from tjutil.h is still necessary for
    TJBench.)
  - Where it makes sense (particularly in the TurboJPEG code), put a blank
    line after variable declaration blocks.
  - Always separate statements in one-liners by two spaces.
  
  The purpose of this was to ease maintenance on my part and also to make
  it easier for contributors to figure out how to format patch
  submissions.  This was admittedly confusing (even to me sometimes) when
  we had 3 or 4 different style conventions in the same source tree.  The
  new convention is more consistent with the formatting of other OSS code
  bases.
  
  This commit corrects deviations from the chosen formatting style in the
  libjpeg API code and reformats the TurboJPEG API code such that it
  conforms to the same standard.
  
  NOTES:
  - Although it is no longer necessary for the function name in function
    declarations to begin in Column 1 (this was historically necessary
    because of the ansi2knr utility, which allowed libjpeg to be built
    with non-ANSI compilers), we retain that formatting for the libjpeg
    code because it improves readability when using libjpeg's function
    attribute macros (GLOBAL(), etc.)
  - This reformatting project was accomplished with the help of AStyle and
    Uncrustify, although neither was completely up to the task, and thus
    a great deal of manual tweaking was required.  Note to developers of
    code formatting utilities:  the libjpeg-turbo code base is an
    excellent test bed, because AFAICT, it breaks every single one of the
    utilities that are currently available.
  - The legacy (MMX, SSE, 3DNow!) assembly code for i386 has been
    formatted to match the SSE2 code (refer to
    ff5685d5344273df321eb63a005eaae19d2496e3.)  I hadn't intended to
    bother with this, but the Loongson MMI implementation demonstrated
    that there is still academic value to the MMX implementation, as an
    algorithmic model for other 64-bit vector implementations.  Thus, it
    is desirable to improve its readability in the same manner as that of
    the SSE2 implementation.
  

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• jdtrans.c

• /*
   * jdtrans.c
   *
   * This file was part of the Independent JPEG Group's software:
   * Copyright (C) 1995-1997, 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.ijg
   * file.
   *
   * This file contains library routines for transcoding decompression,
   * that is, reading raw DCT coefficient arrays from an input JPEG file.
   * The routines in jdapimin.c will also be needed by a transcoder.
   */
  
  #define JPEG_INTERNALS
  #include "jinclude.h"
  #include "jpeglib.h"
  
  
  /* Forward declarations */
  LOCAL(void) transdecode_master_selection(j_decompress_ptr cinfo);
  
  
  /*
   * Read the coefficient arrays from a JPEG file.
   * jpeg_read_header must be completed before calling this.
   *
   * The entire image is read into a set of virtual coefficient-block arrays,
   * one per component.  The return value is a pointer to the array of
   * virtual-array descriptors.  These can be manipulated directly via the
   * JPEG memory manager, or handed off to jpeg_write_coefficients().
   * To release the memory occupied by the virtual arrays, call
   * jpeg_finish_decompress() when done with the data.
   *
   * An alternative usage is to simply obtain access to the coefficient arrays
   * during a buffered-image-mode decompression operation.  This is allowed
   * after any jpeg_finish_output() call.  The arrays can be accessed until
   * jpeg_finish_decompress() is called.  (Note that any call to the library
   * may reposition the arrays, so don't rely on access_virt_barray() results
   * to stay valid across library calls.)
   *
   * Returns NULL if suspended.  This case need be checked only if
   * a suspending data source is used.
   */
  
  GLOBAL(jvirt_barray_ptr *)
  jpeg_read_coefficients(j_decompress_ptr cinfo)
  {
    if (cinfo->global_state == DSTATE_READY) {
      /* First call: initialize active modules */
      transdecode_master_selection(cinfo);
      cinfo->global_state = DSTATE_RDCOEFS;
    }
    if (cinfo->global_state == DSTATE_RDCOEFS) {
      /* Absorb whole file into the coef buffer */
      for (;;) {
        int retcode;
        /* Call progress monitor hook if present */
        if (cinfo->progress != NULL)
          (*cinfo->progress->progress_monitor) ((j_common_ptr)cinfo);
        /* Absorb some more input */
        retcode = (*cinfo->inputctl->consume_input) (cinfo);
        if (retcode == JPEG_SUSPENDED)
          return NULL;
        if (retcode == JPEG_REACHED_EOI)
          break;
        /* Advance progress counter if appropriate */
        if (cinfo->progress != NULL &&
            (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
          if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
            /* startup underestimated number of scans; ratchet up one scan */
            cinfo->progress->pass_limit += (long)cinfo->total_iMCU_rows;
          }
        }
      }
      /* Set state so that jpeg_finish_decompress does the right thing */
      cinfo->global_state = DSTATE_STOPPING;
    }
    /* At this point we should be in state DSTATE_STOPPING if being used
     * standalone, or in state DSTATE_BUFIMAGE if being invoked to get access
     * to the coefficients during a full buffered-image-mode decompression.
     */
    if ((cinfo->global_state == DSTATE_STOPPING ||
         cinfo->global_state == DSTATE_BUFIMAGE) && cinfo->buffered_image) {
      return cinfo->coef->coef_arrays;
    }
    /* Oops, improper usage */
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
    return NULL;                  /* keep compiler happy */
  }
  
  
  /*
   * Master selection of decompression modules for transcoding.
   * This substitutes for jdmaster.c's initialization of the full decompressor.
   */
  
  LOCAL(void)
  transdecode_master_selection(j_decompress_ptr cinfo)
  {
    /* This is effectively a buffered-image operation. */
    cinfo->buffered_image = TRUE;
  
  #if JPEG_LIB_VERSION >= 80
    /* Compute output image dimensions and related values. */
    jpeg_core_output_dimensions(cinfo);
  #endif
  
    /* Entropy decoding: either Huffman or arithmetic coding. */
    if (cinfo->arith_code) {
  #ifdef D_ARITH_CODING_SUPPORTED
      jinit_arith_decoder(cinfo);
  #else
      ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
  #endif
    } else {
      if (cinfo->progressive_mode) {
  #ifdef D_PROGRESSIVE_SUPPORTED
        jinit_phuff_decoder(cinfo);
  #else
        ERREXIT(cinfo, JERR_NOT_COMPILED);
  #endif
      } else
        jinit_huff_decoder(cinfo);
    }
  
    /* Always get a full-image coefficient buffer. */
    jinit_d_coef_controller(cinfo, TRUE);
  
    /* We can now tell the memory manager to allocate virtual arrays. */
    (*cinfo->mem->realize_virt_arrays) ((j_common_ptr)cinfo);
  
    /* Initialize input side of decompressor to consume first scan. */
    (*cinfo->inputctl->start_input_pass) (cinfo);
  
    /* Initialize progress monitoring. */
    if (cinfo->progress != NULL) {
      int nscans;
      /* Estimate number of scans to set pass_limit. */
      if (cinfo->progressive_mode) {
        /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
        nscans = 2 + 3 * cinfo->num_components;
      } else if (cinfo->inputctl->has_multiple_scans) {
        /* For a nonprogressive multiscan file, estimate 1 scan per component. */
        nscans = cinfo->num_components;
      } else {
        nscans = 1;
      }
      cinfo->progress->pass_counter = 0L;
      cinfo->progress->pass_limit = (long)cinfo->total_iMCU_rows * nscans;
      cinfo->progress->completed_passes = 0;
      cinfo->progress->total_passes = 1;
    }
  }
  

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