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+/*
+ * rdppm.c
+ *
+ * Copyright (C) 1991-1997, Thomas G. Lane.
+ * Modified 2009 by Bill Allombert, 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 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_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)))
+
+
+/*
+ * 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++) << 8;
+ temp |= UCH(*bufferptr++);
+ *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++) << 8;
+ temp |= UCH(*bufferptr++);
+ *ptr++ = rescale[temp];
+ temp = UCH(*bufferptr++) << 8;
+ temp |= UCH(*bufferptr++);
+ *ptr++ = rescale[temp];
+ temp = UCH(*bufferptr++) << 8;
+ temp |= UCH(*bufferptr++);
+ *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 */
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