1 files changed, 53 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/com32/lib/sys/vesa/alphatbl.pl b/contrib/syslinux-4.02/com32/lib/sys/vesa/alphatbl.pl
new file mode 100644
index 0000000..d70c76e
--- /dev/null
+++ b/contrib/syslinux-4.02/com32/lib/sys/vesa/alphatbl.pl
@@ -0,0 +1,53 @@
+#!/usr/bin/perl
+#
+# Produce gamma-correction tables for alpha blending, assuming sRGB space.
+#
+
+sub srgb_to_linear($)
+{
+    my($s) = @_;
+
+    if ($s <= 10) {
+	return $s/(255*12.92);
+    } else {
+	return (($s+14.025)/269.025)**2.4;
+    }
+}
+
+sub linear_to_srgb($)
+{
+    my($l) = @_;
+    my $s;
+
+    if ($l <= 0.00304) {
+	$s = 12.92*$l;
+    } else {
+	$s = 1.055*$l**(1.0/2.4) - 0.055;
+    }
+
+    return int($s*255+0.5);
+}
+
+# Header
+print "#include <inttypes.h>\n\n";
+
+#
+# Table 1: convert 8-bit sRGB values to 16-bit linear values
+#
+
+print "const uint16_t __vesacon_srgb_to_linear[256] = {\n";
+for ($i = 0; $i <= 255; $i++) {
+    printf "\t%5d,\n", int(srgb_to_linear($i)*65535+0.5);
+}
+print "};\n\n";
+
+#
+# Table 2: convert linear values in the range [0, 65535*255],
+#          shifted right by 12 bits, to sRGB
+#
+
+print "const uint8_t __vesacon_linear_to_srgb[4080] = {\n";
+for ($i = 0; $i <= 4079; $i++) {
+    printf "\t%3d,\n", linear_to_srgb(($i+0.5)/4079.937744);
+}
+print "};\n\n";