--- /dev/null
+/*
+ * op_gammatable - generate a gamma table for OMAP's DSS
+ *
+ * Copyright (c) 2012, Gražvydas Ignotas
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * * Neither the name of the organization nor the
+ * names of its contributors may be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+
+static void usage(const char *argv0)
+{
+ fprintf(stderr, "usage:\n");
+ fprintf(stderr, "%s [-n] {<gamma> | <gamma_r> <gamma_g> <gamma_b>}\n",
+ argv0);
+ exit(1);
+}
+
+int main(int argc, char *argv[])
+{
+ unsigned int v, r, g, b;
+ float gamma[3] = { 0.f, };
+ int negative = 0, ptod = 0, half = 0;
+ int i, arg = 1;
+
+ if (argc < 2)
+ usage(argv[0]);
+ while (arg < argc && argv[arg][0] == '-') {
+ if (strcmp(argv[arg], "-h") == 0)
+ usage(argv[0]);
+ else if (strcmp(argv[arg], "-n") == 0)
+ negative = 1;
+ else if (strcmp(argv[arg], "-ptod") == 0)
+ ptod = 1;
+ else if (strcmp(argv[arg], "-half") == 0)
+ half = 1;
+ else
+ fprintf(stderr, "%s: ignoring %s\n",
+ argv[0], argv[arg]);
+ arg++;
+ }
+
+ if (argc - arg == 3) {
+ gamma[0] = atof(argv[arg++]);
+ gamma[1] = atof(argv[arg++]);
+ gamma[2] = atof(argv[arg++]);
+ }
+ else if (argc - arg == 1)
+ gamma[0] = gamma[1] = gamma[2] = atof(argv[arg++]);
+ else
+ usage(argv[0]);
+
+ if (gamma[0] <= 0.f || gamma[1] <= 0.f || gamma[2] <= 0.f) {
+ fprintf(stderr, "invalid arguments: %.3f %.3f %.3f\n",
+ gamma[0], gamma[1], gamma[2]);
+ usage(argv[0]);
+ }
+
+ for (i = 0; i < 256; i++) {
+ // based on http://www.teamten.com/lawrence/graphics/gamma/
+ r = (unsigned int) (255.f * powf((float)i / 255.f, 1.f / gamma[0]) + 0.5f);
+ g = (unsigned int) (255.f * powf((float)i / 255.f, 1.f / gamma[1]) + 0.5f);
+ b = (unsigned int) (255.f * powf((float)i / 255.f, 1.f / gamma[2]) + 0.5f);
+
+ v = (r << 16) | (g << 8) | b;
+ if (negative)
+ v ^= 0xffffff;
+ if (half)
+ v = (v >> 1) & 0x7f7f7f;
+ if (ptod)
+ v &= 0xff7fff;
+
+ printf("0x%06x ", v);
+ }
+ printf("\n");
+
+ return 0;
+}