[libpng16] New 'tools' directory containing tools used to generate libpng code.

ANNOUNCE

@@ -1,5 +1,5 @@
 
-Libpng 1.6.0alpha01 - November 28, 2011
+Libpng 1.6.0alpha01 - November 29, 2011
 
 This is not intended to be a public release.  It will be replaced
 within a few weeks by a public version or by another test version.
@@ -107,7 +107,7 @@ Version 1.5.7beta05 [(PENDING RELEASE)]
   Added MINGW support to CMakeLists.txt
   Reject invalid compression flag or method when reading the iTXt chunk.
 
-Version 1.6.0alpha01 [November 28, 2011]
+Version 1.6.0alpha01 [November 29, 2011]
   Removed machine-generated configure files from the GIT repository (they will
     continue to appear in the tarball distributions).
   Restored the new 'simplified' API, which was deleted from libpng-1.5.7.
@@ -130,7 +130,7 @@ Version 1.6.0alpha01 [November 28, 2011]
     image that has a sufficiently large row size (rather than simply failing
     to read such images).
   Replaced an "#if" with "ifdef" in pngrtran.c
-  Revised #if PNG_DO_BC blocks in png.c (use #ifdef and add #else)
+  New tools directory containing tools used to generate libpng code.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net:
 (subscription required; visit

CHANGES

@@ -3752,7 +3752,7 @@ Version 1.5.7beta05 [(PENDING RELEASE)]
   Added MINGW support to CMakeLists.txt
   Reject invalid compression flag or method when reading the iTXt chunk.
 
-Version 1.6.0alpha01 [November 28, 2011]
+Version 1.6.0alpha01 [November 29, 2011]
   Removed machine-generated configure files from the GIT repository (they will
     continue to appear in the tarball distributions).
   Restored the new 'simplified' API, which was deleted from libpng-1.5.7.
@@ -3775,7 +3775,7 @@ Version 1.6.0alpha01 [November 28, 2011]
     image that has a sufficiently large row size (rather than simply failing
     to read such images).
   Replaced an "#if" with "ifdef" in pngrtran.c
-  Revised #if PNG_DO_BC blocks in png.c (use #ifdef and add #else)
+  New tools directory containing tools used to generate libpng code.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

contrib/libtests/pngstest.c

@@ -28,7 +28,7 @@
 
 #include "../../png.h"
 
-#include "../sRGBtables/sRGB.h"
+#include "../tools/sRGB.h"
 
 /* The following is to support direct compilation of this file as C++ */
 #ifdef __cplusplus

contrib/tools/README.txt

@@ -0,0 +1,26 @@
+This directory (contrib/tools) contains tools used by the authors of libpng.
+
+Code and data placed in this directory is not required to build libpng,
+however the code in this directory has been used to generate data or code in
+the body of the libpng source.  The source code idenftifies where this has
+been done.  Code in this directory may not compile on all operating systems
+that libpng supports.
+
+NO COPYRIGHT RIGHTS ARE CLAIMED TO ANY OF THE FILES IN THIS DIRECTORY.
+
+To the extent possible under law, the authors have waived all copyright and
+related or neighboring rights to this work.  This work is published from:
+United States.
+
+The files may be used freely in any way.
+
+The source code and comments in this directory are the original work of the
+people named below.  No other person or organization has made contributions to
+the work in this directory.
+
+ORIGINAL AUTHORS
+    The following people have contributed to the code in this directory.  None
+    of the people below claim any rights with regard to the contents of this
+    directory.
+
+    John Bowler <jbowler@acm.org>

contrib/tools/cvtcolor.c

@@ -1,14 +1,14 @@
 /*-
  * convert.c
  *
+ * Last changed in libpng 1.6.0 [(PENDING RELEASE)]
+ *
+ * COPYRIGHT: Written by John Cunningham Bowler, 2011.
+ * To the extent possible under law, the author has waived all copyright and
+ * related or neighboring rights to this work.  This work is published from:
+ * United States.
+ *
  * Convert 8-bit sRGB or 16-bit linear values to another format.
- *
- * Last changed in libpng 1.5.7 [(PENDING RELEASE)]
- * Copyright (c) 2011 Written by John Cunningham Bowler
- *
- * This code is released under the libpng license.
- * For conditions of distribution and use, see the disclaimer
- * and license in png.h
  */
 #define _ISOC99_SOURCE 1
 

contrib/tools/intgamma.sh

@@ -0,0 +1,110 @@
+#!/bin/sh
+#
+# intgamma.sh
+#
+# Last changed in libpng 1.6.0 [(PENDING RELEASE)]
+#
+# COPYRIGHT: Written by John Cunningham Bowler, 2011.
+# To the extent possible under law, the author has waived all copyright and
+# related or neighboring rights to this work.  This work is published from:
+# United States.
+#
+# Shell script to generate png.c 8 and 16 bit log tables (see the code in png.c
+# for details).
+#
+# This script uses the "bc" arbitrary precision calculator to calculate 32 bit
+# fixed point values of logarithms appropriate to finding the log of an 8-bit
+# (0..255) value and a similar table for the exponent calculation.
+#
+# "bc" must be on the path when the script is executed, the math library (-l)
+# must be available
+#
+# function to print out a list of numbers as integers; the function truncates
+# the integers which must be one-per-line
+function print(){
+   awk 'BEGIN{
+      str = ""
+   }
+   {
+      sub("\\.[0-9]*$", "")
+      if ($0 == "")
+         $0 = "0"
+
+      if (str == "")
+         t = "   " $0 "U"
+      else
+         t = str ", " $0 "U"
+
+      if (length(t) >= 80) {
+         print str ","
+         str = "   " $0 "U"
+      } else
+         str = t
+   }
+   END{
+      print str
+   }'
+}
+#
+# The logarithm table.
+cat <<END
+/* 8-bit log table: png_8bit_l2[128]
+ * This is a table of -log(value/255)/log(2) for 'value' in the range 128 to
+ * 255, so it's the base 2 logarithm of a normalized 8-bit floating point
+ * mantissa.  The numbers are 32-bit fractions.
+ */
+static const png_uint_32
+png_8bit_l2[128] =
+{
+END
+#
+bc -lqws <<END | print
+f=65536*65536/l(2)
+for (i=128;i<256;++i) { .5 - l(i/255)*f; }
+END
+echo '};'
+echo
+#
+# The exponent table.
+cat <<END
+/* The 'exp()' case must invert the above, taking a 20-bit fixed point
+ * logarithmic value and returning a 16 or 8-bit number as appropriate.  In
+ * each case only the low 16 bits are relevant - the fraction - since the
+ * integer bits (the top 4) simply determine a shift.
+ *
+ * The worst case is the 16-bit distinction between 65535 and 65534, this
+ * requires perhaps spurious accuracty in the decoding of the logarithm to
+ * distinguish log2(65535/65534.5) - 10^-5 or 17 bits.  There is little chance
+ * of getting this accuracy in practice.
+ *
+ * To deal with this the following exp() function works out the exponent of the
+ * frational part of the logarithm by using an accurate 32-bit value from the
+ * top four fractional bits then multiplying in the remaining bits.
+ */
+static const png_uint_32
+png_32bit_exp[16] =
+{
+END
+#
+bc -lqws <<END | print
+f=l(2)/16
+for (i=0;i<16;++i) {
+   x = .5 + e(-i*f)*2^32;
+   if (x >= 2^32) x = 2^32-1;
+   x;
+}
+END
+echo '};'
+echo
+#
+# And the table of adjustment values.
+cat <<END
+/* Adjustment table; provided to explain the numbers in the code below. */
+#if 0
+END
+bc -lqws <<END | awk '{ printf "%5d %s\n", 12-NR, $0 }'
+for (i=11;i>=0;--i){
+   (1 - e(-(2^i)/65536*l(2))) * 2^(32-i)
+}
+END
+echo '#endif'

contrib/tools/makesRGB.c

@@ -1,11 +1,11 @@
 /* makesRGB.c -- build sRGB-to-linear and linear-to-sRGB conversion tables
  *
- * Last changed in libpng 1.5.7 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.0 [(PENDING RELEASE)]
- * Copyright (c) 2011 John Cunningham Bowler
  *
- * This code is released under the libpng license.
+ * COPYRIGHT: Written by John Cunningham Bowler, 2011.
- * For conditions of distribution and use, see the disclaimer
+ * To the extent possible under law, the author has waived all copyright and
- * and license in png.h
+ * related or neighboring rights to this work.  This work is published from:
+ * United States.
  *
  * Make a table to convert 8-bit sRGB encoding values into the closest 16-bit
  * linear value.

contrib/tools/sRGB.h

@@ -1,12 +1,12 @@
 /*-
  * sRGB.h
  *
- * Last changed in libpng 1.5.7 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.0 [(PENDING RELEASE)]
- * Copyright (c) 2011 John Cunningham Bowler
  *
- * This code is released under the libpng license.
+ * COPYRIGHT: Written by John Cunningham Bowler, 2011.
- * For conditions of distribution and use, see the disclaimer
+ * To the extent possible under law, the author has waived all copyright and
- * and license in png.h
+ * related or neighboring rights to this work.  This work is published from:
+ * United States.
  *
  * Utility file; not actually a header, this contains definitions of sRGB
  * calculation functions for inclusion in those test programs that need them.