/* * rdppm.c * * Copyright (C) 1991-1997, 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 routines to read input images in PPM/PGM format. * The extended 2-byte-per-sample raw PPM/PGM formats are supported. * The PBMPLUS library is NOT required to compile this software * (but it is highly useful as a set of PPM image manipulation programs). * * 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 PPM format). */#include "cdjpeg.h"   /* Common decls for cjpeg/djpeg applications */#ifdef PPM_SUPPORTED/* Portions of this code are based on the PBMPLUS library, which is:**** Copyright (C) 1988 by Jef Poskanzer.**** Permission to use, copy, modify, and distribute this software and its** documentation for any purpose and without fee is hereby granted, provided** that the above copyright notice appear in all copies and that both that** copyright notice and this permission notice appear in supporting** documentation.  This software is provided "as is" without express or** implied warranty.*//* Macros to deal with unsigned chars as efficiently as compiler allows */#ifdef HAVE_UNSIGNED_CHARtypedef unsigned char U_CHAR;#define UCH(x)  ((int) (x))#else /* !HAVE_UNSIGNED_CHAR */#ifdef CHAR_IS_UNSIGNEDtypedef char U_CHAR;#define UCH(x)  ((int) (x))#elsetypedef 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)))/* * On most systems, reading individual bytes with getc() is drastically less * efficient than buffering a row at a time with fread().  On PCs, we must * allocate the buffer in near data space, because we are assuming small-data * memory model, wherein fread() can't reach far memory.  If you need to * process very wide images on a PC, you might have to compile in large-memory * model, or else replace fread() with a getc() loop --- which will be much * slower. *//* Private version of data source object */typedef struct {  struct cjpeg_source_struct pub; /* public fields */  U_CHAR *iobuffer;   /* non-FAR pointer to I/O buffer */  JSAMPROW pixrow;    /* FAR pointer to same */  size_t buffer_width;    /* width of I/O buffer */  JSAMPLE *rescale;   /* => maxval-remapping array, or NULL */} ppm_source_struct;typedef ppm_source_struct * ppm_source_ptr;LOCAL(int)pbm_getc (FILE * infile)/* Read next char, skipping over any comments *//* A comment/newline sequence is returned as a newline */{  register int ch;  ch = getc(infile);  if (ch == '#') {    do {      ch = getc(infile);    } while (ch != '\n' && ch != EOF);  }  return ch;}LOCAL(unsigned int)read_pbm_integer (j_compress_ptr cinfo, FILE * infile)/* Read an unsigned decimal integer from the PPM file *//* Swallows one trailing character after the integer *//* Note that on a 16-bit-int machine, only values up to 64k can be read. *//* This should not be a problem in practice. */{  register int ch;  register unsigned int val;  /* Skip any leading whitespace */  do {    ch = pbm_getc(infile);    if (ch == EOF)      ERREXIT(cinfo, JERR_INPUT_EOF);  } while (ch == ' ' || ch == '\t' || ch == '\n' || ch == '\r');  if (ch < '0' || ch > '9')    ERREXIT(cinfo, JERR_PPM_NONNUMERIC);  val = ch - '0';  while ((ch = pbm_getc(infile)) >= '0' && ch <= '9') {    val *= 10;    val += ch - '0';  }  return val;}/* * Read one row of pixels. * * We provide several different versions depending on input file format. * In all cases, input is scaled to the size of JSAMPLE. * * A really fast path is provided for reading byte/sample raw files with * maxval = MAXJSAMPLE, which is the normal case for 8-bit data. */METHODDEF(JDIMENSION)get_text_gray_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)/* This version is for reading text-format PGM files with any maxval */{  ppm_source_ptr source = (ppm_source_ptr) sinfo;  FILE * infile = source->pub.input_file;  register JSAMPROW ptr;  register JSAMPLE *rescale = source->rescale;  JDIMENSION col;  ptr = source->pub.buffer[0];  for (col = cinfo->image_width; col > 0; col--) {    *ptr++ = rescale[read_pbm_integer(cinfo, infile)];  }  return 1;}METHODDEF(JDIMENSION)get_text_rgb_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)/* This version is for reading text-format PPM files with any maxval */{  ppm_source_ptr source = (ppm_source_ptr) sinfo;  FILE * infile = source->pub.input_file;  register JSAMPROW ptr;  register JSAMPLE *rescale = source->rescale;  JDIMENSION col;  ptr = source->pub.buffer[0];  for (col = cinfo->image_width; col > 0; col--) {    *ptr++ = rescale[read_pbm_integer(cinfo, infile)];    *ptr++ = rescale[read_pbm_integer(cinfo, infile)];    *ptr++ = rescale[read_pbm_integer(cinfo, infile)];  }  return 1;}METHODDEF(JDIMENSION)get_scaled_gray_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)/* This version is for reading raw-byte-format PGM files with any maxval */{  ppm_source_ptr source = (ppm_source_ptr) sinfo;  register JSAMPROW ptr;  register U_CHAR * bufferptr;  register JSAMPLE *rescale = source->rescale;  JDIMENSION col;  if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))    ERREXIT(cinfo, JERR_INPUT_EOF);  ptr = source->pub.buffer[0];  bufferptr = source->iobuffer;  for (col = cinfo->image_width; col > 0; col--) {    *ptr++ = rescale[UCH(*bufferptr++)];  }  return 1;}METHODDEF(JDIMENSION)get_scaled_rgb_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)/* This version is for reading raw-byte-format PPM files with any maxval */{  ppm_source_ptr source = (ppm_source_ptr) sinfo;  register JSAMPROW ptr;  register U_CHAR * bufferptr;  register JSAMPLE *rescale = source->rescale;  JDIMENSION col;  if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))    ERREXIT(cinfo, JERR_INPUT_EOF);  ptr = source->pub.buffer[0];  bufferptr = source->iobuffer;  for (col = cinfo->image_width; col > 0; col--) {    *ptr++ = rescale[UCH(*bufferptr++)];    *ptr++ = rescale[UCH(*bufferptr++)];    *ptr++ = rescale[UCH(*bufferptr++)];  }  return 1;}METHODDEF(JDIMENSION)get_raw_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)/* This version is for reading raw-byte-format files with maxval = MAXJSAMPLE. * In this case we just read right into the JSAMPLE buffer! * Note that same code works for PPM and PGM files. */{  ppm_source_ptr source = (ppm_source_ptr) sinfo;  if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))    ERREXIT(cinfo, JERR_INPUT_EOF);  return 1;}METHODDEF(JDIMENSION)get_word_gray_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)/* This version is for reading raw-word-format PGM files with any maxval */{  ppm_source_ptr source = (ppm_source_ptr) sinfo;  register JSAMPROW ptr;  register U_CHAR * bufferptr;  register JSAMPLE *rescale = source->rescale;  JDIMENSION col;  if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))    ERREXIT(cinfo, JERR_INPUT_EOF);  ptr = source->pub.buffer[0];  bufferptr = source->iobuffer;  for (col = cinfo->image_width; col > 0; col--) {    register int temp;    temp  = UCH(*bufferptr++);    temp |= UCH(*bufferptr++) << 8;    *ptr++ = rescale[temp];  }  return 1;}METHODDEF(JDIMENSION)get_word_rgb_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)/* This version is for reading raw-word-format PPM files with any maxval */{  ppm_source_ptr source = (ppm_source_ptr) sinfo;  register JSAMPROW ptr;  register U_CHAR * bufferptr;  register JSAMPLE *rescale = source->rescale;  JDIMENSION col;  if (! ReadOK(source->pub.input_file, source->iobuffer, source->buffer_width))    ERREXIT(cinfo, JERR_INPUT_EOF);  ptr = source->pub.buffer[0];  bufferptr = source->iobuffer;  for (col = cinfo->image_width; col > 0; col--) {    register int temp;    temp  = UCH(*bufferptr++);    temp |= UCH(*bufferptr++) << 8;    *ptr++ = rescale[temp];    temp  = UCH(*bufferptr++);    temp |= UCH(*bufferptr++) << 8;    *ptr++ = rescale[temp];    temp  = UCH(*bufferptr++);    temp |= UCH(*bufferptr++) << 8;    *ptr++ = rescale[temp];  }  return 1;}/* * Read the file header; return image size and component count. */METHODDEF(void)start_input_ppm (j_compress_ptr cinfo, cjpeg_source_ptr sinfo){  ppm_source_ptr source = (ppm_source_ptr) sinfo;  int c;  unsigned int w, h, maxval;  boolean need_iobuffer, use_raw_buffer, need_rescale;  if (getc(source->pub.input_file) != 'P')    ERREXIT(cinfo, JERR_PPM_NOT);  c = getc(source->pub.input_file); /* subformat discriminator character */  /* detect unsupported variants (ie, PBM) before trying to read header */  switch (c) {  case '2':     /* it's a text-format PGM file */  case '3':     /* it's a text-format PPM file */  case '5':     /* it's a raw-format PGM file */  case '6':     /* it's a raw-format PPM file */    break;  default:    ERREXIT(cinfo, JERR_PPM_NOT);    break;  }  /* fetch the remaining header info */  w = read_pbm_integer(cinfo, source->pub.input_file);  h = read_pbm_integer(cinfo, source->pub.input_file);  maxval = read_pbm_integer(cinfo, source->pub.input_file);  if (w <= 0 || h <= 0 || maxval <= 0) /* error check */    ERREXIT(cinfo, JERR_PPM_NOT);  cinfo->data_precision = BITS_IN_JSAMPLE; /* we always rescale data to this */  cinfo->image_width = (JDIMENSION) w;  cinfo->image_height = (JDIMENSION) h;  /* initialize flags to most common settings */  need_iobuffer = TRUE;   /* do we need an I/O buffer? */  use_raw_buffer = FALSE; /* do we map input buffer onto I/O buffer? */  need_rescale = TRUE;    /* do we need a rescale array? */  switch (c) {  case '2':     /* it's a text-format PGM file */    cinfo->input_components = 1;    cinfo->in_color_space = JCS_GRAYSCALE;    TRACEMS2(cinfo, 1, JTRC_PGM_TEXT, w, h);    source->pub.get_pixel_rows = get_text_gray_row;    need_iobuffer = FALSE;    break;  case '3':     /* it's a text-format PPM file */    cinfo->input_components = 3;    cinfo->in_color_space = JCS_RGB;    TRACEMS2(cinfo, 1, JTRC_PPM_TEXT, w, h);    source->pub.get_pixel_rows = get_text_rgb_row;    need_iobuffer = FALSE;    break;  case '5':     /* it's a raw-format PGM file */    cinfo->input_components = 1;    cinfo->in_color_space = JCS_GRAYSCALE;    TRACEMS2(cinfo, 1, JTRC_PGM, w, h);    if (maxval > 255) {      source->pub.get_pixel_rows = get_word_gray_row;    } else if (maxval == MAXJSAMPLE && SIZEOF(JSAMPLE) == SIZEOF(U_CHAR)) {      source->pub.get_pixel_rows = get_raw_row;      use_raw_buffer = TRUE;      need_rescale = FALSE;    } else {      source->pub.get_pixel_rows = get_scaled_gray_row;    }    break;  case '6':     /* it's a raw-format PPM file */    cinfo->input_components = 3;    cinfo->in_color_space = JCS_RGB;    TRACEMS2(cinfo, 1, JTRC_PPM, w, h);    if (maxval > 255) {      source->pub.get_pixel_rows = get_word_rgb_row;    } else if (maxval == MAXJSAMPLE && SIZEOF(JSAMPLE) == SIZEOF(U_CHAR)) {      source->pub.get_pixel_rows = get_raw_row;      use_raw_buffer = TRUE;      need_rescale = FALSE;    } else {      source->pub.get_pixel_rows = get_scaled_rgb_row;    }    break;  }  /* Allocate space for I/O buffer: 1 or 3 bytes or words/pixel. */  if (need_iobuffer) {    source->buffer_width = (size_t) w * cinfo->input_components *      ((maxval<=255) ? SIZEOF(U_CHAR) : (2*SIZEOF(U_CHAR)));    source->iobuffer = (U_CHAR *)      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,          source->buffer_width);  }  /* Create compressor input buffer. */  if (use_raw_buffer) {    /* For unscaled raw-input case, we can just map it onto the I/O buffer. */    /* Synthesize a JSAMPARRAY pointer structure */    /* Cast here implies near->far pointer conversion on PCs */    source->pixrow = (JSAMPROW) source->iobuffer;    source->pub.buffer = & source->pixrow;    source->pub.buffer_height = 1;  } else {    /* Need to translate anyway, so make a separate sample buffer. */    source->pub.buffer = (*cinfo->mem->alloc_sarray)      ((j_common_ptr) cinfo, JPOOL_IMAGE,       (JDIMENSION) w * cinfo->input_components, (JDIMENSION) 1);    source->pub.buffer_height = 1;  }  /* Compute the rescaling array if required. */  if (need_rescale) {    INT32 val, half_maxval;    /* On 16-bit-int machines we have to be careful of maxval = 65535 */    source->rescale = (JSAMPLE *)      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,          (size_t) (((long) maxval + 1L) * SIZEOF(JSAMPLE)));    half_maxval = maxval / 2;    for (val = 0; val <= (INT32) maxval; val++) {      /* The multiplication here must be done in 32 bits to avoid overflow */      source->rescale[val] = (JSAMPLE) ((val*MAXJSAMPLE + half_maxval)/maxval);    }  }}/* * Finish up at the end of the file. */METHODDEF(void)finish_input_ppm (j_compress_ptr cinfo, cjpeg_source_ptr sinfo){  /* no work */}/* * The module selection routine for PPM format input. */GLOBAL(cjpeg_source_ptr)jinit_read_ppm (j_compress_ptr cinfo){  ppm_source_ptr source;  /* Create module interface object */  source = (ppm_source_ptr)      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,          SIZEOF(ppm_source_struct));  /* Fill in method ptrs, except get_pixel_rows which start_input sets */  source->pub.start_input = start_input_ppm;  source->pub.finish_input = finish_input_ppm;  return (cjpeg_source_ptr) source;}#endif /* PPM_SUPPORTED */