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Diffstat (limited to 'Build/source/libs/libpng/libpng-1.6.2/contrib/tools/intgamma.sh')
-rw-r--r-- | Build/source/libs/libpng/libpng-1.6.2/contrib/tools/intgamma.sh | 110 |
1 files changed, 0 insertions, 110 deletions
diff --git a/Build/source/libs/libpng/libpng-1.6.2/contrib/tools/intgamma.sh b/Build/source/libs/libpng/libpng-1.6.2/contrib/tools/intgamma.sh deleted file mode 100644 index 41c5d6dd278..00000000000 --- a/Build/source/libs/libpng/libpng-1.6.2/contrib/tools/intgamma.sh +++ /dev/null @@ -1,110 +0,0 @@ -#!/bin/sh -# -# intgamma.sh -# -# Last changed in libpng 1.6.0 [February 14, 2013] -# -# COPYRIGHT: Written by John Cunningham Bowler, 2013. -# 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-bit 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, and the math library -# (-lm) 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 accuracy 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' |