auto import from //depot/cupcake/@135843
diff --git a/contrib/gregbook/readppm.c b/contrib/gregbook/readppm.c
new file mode 100644
index 0000000..be9a56d
--- /dev/null
+++ b/contrib/gregbook/readppm.c
@@ -0,0 +1,179 @@
+/*---------------------------------------------------------------------------
+
+ rpng - simple PNG display program readppm.c
+
+ ---------------------------------------------------------------------------
+
+ This is a special-purpose replacement for readpng.c that allows binary
+ PPM files to be used in place of PNG images.
+
+ ---------------------------------------------------------------------------
+
+ Copyright (c) 1998-2007 Greg Roelofs. All rights reserved.
+
+ This software is provided "as is," without warranty of any kind,
+ express or implied. In no event shall the author or contributors
+ be held liable for any damages arising in any way from the use of
+ this software.
+
+ The contents of this file are DUAL-LICENSED. You may modify and/or
+ redistribute this software according to the terms of one of the
+ following two licenses (at your option):
+
+
+ LICENSE 1 ("BSD-like with advertising clause"):
+
+ Permission is granted to anyone to use this software for any purpose,
+ including commercial applications, and to alter it and redistribute
+ it freely, subject to the following restrictions:
+
+ 1. Redistributions of source code must retain the above copyright
+ notice, disclaimer, and this list of conditions.
+ 2. Redistributions in binary form must reproduce the above copyright
+ notice, disclaimer, and this list of conditions in the documenta-
+ tion and/or other materials provided with the distribution.
+ 3. All advertising materials mentioning features or use of this
+ software must display the following acknowledgment:
+
+ This product includes software developed by Greg Roelofs
+ and contributors for the book, "PNG: The Definitive Guide,"
+ published by O'Reilly and Associates.
+
+
+ LICENSE 2 (GNU GPL v2 or later):
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+ ---------------------------------------------------------------------------*/
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "readpng.h" /* typedefs, common macros, public prototypes */
+
+
+ulg width, height;
+int bit_depth, color_type, channels;
+uch *image_data = NULL;
+FILE *saved_infile;
+
+
+void readpng_version_info()
+{
+ fprintf(stderr, " Compiled without libpng, zlib or PBMPLUS/NetPBM.\n");
+}
+
+
+/* return value = 0 for success, 1 for bad sig, 2 for bad IHDR, 4 for no mem */
+
+int readpng_init(FILE *infile, ulg *pWidth, ulg *pHeight)
+{
+ static uch ppmline[256];
+ int maxval;
+
+
+ saved_infile = infile;
+
+ fgets(ppmline, 256, infile);
+ if (ppmline[0] != 'P' || ppmline[1] != '6') {
+ fprintf(stderr, "ERROR: not a PPM file\n");
+ return 1;
+ }
+ /* possible color types: P5 = grayscale (0), P6 = RGB (2), P8 = RGBA (6) */
+ if (ppmline[1] == '6') {
+ color_type = 2;
+ channels = 3;
+ } else if (ppmline[1] == '8') {
+ color_type = 6;
+ channels = 4;
+ } else /* if (ppmline[1] == '5') */ {
+ color_type = 0;
+ channels = 1;
+ }
+
+ do {
+ fgets(ppmline, 256, infile);
+ } while (ppmline[0] == '#');
+ sscanf(ppmline, "%lu %lu", &width, &height);
+
+ do {
+ fgets(ppmline, 256, infile);
+ } while (ppmline[0] == '#');
+ sscanf(ppmline, "%d", &maxval);
+ if (maxval != 255) {
+ fprintf(stderr, "ERROR: maxval = %d\n", maxval);
+ return 2;
+ }
+ bit_depth = 8;
+
+ *pWidth = width;
+ *pHeight = height;
+
+ return 0;
+}
+
+
+
+
+/* returns 0 if succeeds, 1 if fails due to no bKGD chunk, 2 if libpng error;
+ * scales values to 8-bit if necessary */
+
+int readpng_get_bgcolor(uch *red, uch *green, uch *blue)
+{
+ return 1;
+}
+
+
+
+
+/* display_exponent == LUT_exponent * CRT_exponent */
+
+uch *readpng_get_image(double display_exponent, int *pChannels, ulg *pRowbytes)
+{
+ ulg rowbytes;
+
+
+ /* expand palette images to RGB, low-bit-depth grayscale images to 8 bits,
+ * transparency chunks to full alpha channel; strip 16-bit-per-sample
+ * images to 8 bits per sample; and convert grayscale to RGB[A] */
+
+ /* GRR WARNING: grayscale needs to be expanded and channels reset! */
+
+ *pRowbytes = rowbytes = channels*width;
+ *pChannels = channels;
+
+ if ((image_data = (uch *)malloc(rowbytes*height)) == NULL) {
+ return NULL;
+ }
+
+ Trace((stderr, "readpng_get_image: rowbytes = %ld, height = %ld\n", rowbytes, height));
+
+
+ /* now we can go ahead and just read the whole image */
+
+ fread(image_data, 1L, rowbytes*height, saved_infile);
+
+
+ return image_data;
+}
+
+
+void readpng_cleanup(int free_image_data)
+{
+ if (free_image_data && image_data) {
+ free(image_data);
+ image_data = NULL;
+ }
+}