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src/Source/LibJPEG/rdbmp.c  view on Meta::CPAN

/*
 * rdbmp.c
 *
 * Copyright (C) 1994-1996, Thomas G. Lane.
 * Modified 2009-2010 by Guido Vollbeding.
 * 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 routines to read input images in Microsoft "BMP"
 * format (MS Windows 3.x, OS/2 1.x, and OS/2 2.x flavors).
 * Currently, only 8-bit and 24-bit images are supported, not 1-bit or
 * 4-bit (feeding such low-depth images into JPEG would be silly anyway).
 * Also, we don't support RLE-compressed files.
 *
 * These routines may need modification for non-Unix environments or
 * specialized applications.  As they stand, they assume input from
 * an ordinary stdio stream.  They further assume that reading begins
 * at the start of the file; start_input may need work if the
 * user interface has already read some data (e.g., to determine that
 * the file is indeed BMP format).
 *
 * This code contributed by James Arthur Boucher.
 */

#include "cdjpeg.h"		/* Common decls for cjpeg/djpeg applications */

#ifdef BMP_SUPPORTED


/* Macros to deal with unsigned chars as efficiently as compiler allows */

#ifdef HAVE_UNSIGNED_CHAR
typedef unsigned char U_CHAR;
#define UCH(x)	((int) (x))
#else /* !HAVE_UNSIGNED_CHAR */
#ifdef CHAR_IS_UNSIGNED
typedef char U_CHAR;
#define UCH(x)	((int) (x))
#else
typedef char U_CHAR;
#define UCH(x)	((int) (x) & 0xFF)
#endif
#endif /* HAVE_UNSIGNED_CHAR */


#define	ReadOK(file,buffer,len)	(JFREAD(file,buffer,len) == ((size_t) (len)))


/* Private version of data source object */

typedef struct _bmp_source_struct * bmp_source_ptr;

typedef struct _bmp_source_struct {
  struct cjpeg_source_struct pub; /* public fields */

  j_compress_ptr cinfo;		/* back link saves passing separate parm */

  JSAMPARRAY colormap;		/* BMP colormap (converted to my format) */

  jvirt_sarray_ptr whole_image;	/* Needed to reverse row order */
  JDIMENSION source_row;	/* Current source row number */
  JDIMENSION row_width;		/* Physical width of scanlines in file */

  int bits_per_pixel;		/* remembers 8- or 24-bit format */
} bmp_source_struct;


LOCAL(int)
read_byte (bmp_source_ptr sinfo)
/* Read next byte from BMP file */
{
  register FILE *infile = sinfo->pub.input_file;
  register int c;

  if ((c = getc(infile)) == EOF)
    ERREXIT(sinfo->cinfo, JERR_INPUT_EOF);
  return c;
}


LOCAL(void)
read_colormap (bmp_source_ptr sinfo, int cmaplen, int mapentrysize)
/* Read the colormap from a BMP file */
{
  int i;

  switch (mapentrysize) {
  case 3:
    /* BGR format (occurs in OS/2 files) */
    for (i = 0; i < cmaplen; i++) {