1 files changed, 130 insertions, 0 deletions
diff --git a/plug-ins/file-dds/mktables.c b/plug-ins/file-dds/mktables.c
new file mode 100644
index 0000000..99eef6d
--- /dev/null
+++ b/plug-ins/file-dds/mktables.c
@@ -0,0 +1,130 @@
+#include <stdlib.h>
+#include <stdio.h>
+
+static int mul8bit(int a, int b)
+{
+   int t = a * b + 128;
+   return((t + (t >> 8)) >> 8);
+}
+
+static int lerp13(int a, int b)
+{
+#if 0
+   return(a + mul8bit(b - a, 0x55));
+#else
+   return((2 * a + b) / 3);
+#endif   
+}
+
+static void prepare_opt_table(unsigned char *tab,
+                              const unsigned char *expand, int size)
+{
+   int i, mn, mx, bestE, minE, maxE, e;
+   
+   for(i = 0; i < 256; ++i)
+   {
+      bestE = 256 * 100;
+      
+      for(mn = 0; mn < size; ++mn)
+      {
+         for(mx = 0; mx < size; ++mx)
+         {
+            minE = expand[mn];
+            maxE = expand[mx];
+            e = abs(lerp13(maxE, minE) - i) * 100;
+            
+            e += abs(mx - mn) * 3;
+            
+            if(e < bestE)
+            {
+               tab[i * 2 + 0] = mx;
+               tab[i * 2 + 1] = mn;
+               bestE = e;
+            }
+         }
+      }
+   }
+}
+
+#if 0
+int main(void)
+{
+   FILE *fp;
+   int i, v;
+   unsigned char expand5[32];
+   unsigned char expand6[64];
+   unsigned char quantRB[256 + 16];
+   unsigned char quantG[256 + 16];
+   unsigned char omatch5[256][2];
+   unsigned char omatch6[256][2];
+   
+   fp = fopen("dxt_tables.h", "w");
+   fprintf(fp,
+           "#ifndef DXT_TABLES_H\n"
+           "#define DXT_TABLES_H\n\n");
+   
+   for(i = 0; i < 32; ++i)
+      expand5[i] = (i << 3) | (i >> 2);
+
+   for(i = 0; i < 64; ++i)
+      expand6[i] = (i << 2) | (i >> 4);
+   
+   for(i = 0; i < 256 + 16; ++i)
+   {
+      v = i - 8;
+      if(v < 0) v = 0;
+      if(v > 255) v = 255;
+      quantRB[i] = expand5[mul8bit(v, 31)];
+      quantG[i] = expand6[mul8bit(v, 63)];
+   }
+ 
+   fprintf(fp,
+           "static const unsigned char quantRB[256 + 16] =\n"
+           "{");
+   for(i = 0; i < 256 + 16; ++i)
+   {
+      if(i % 8 == 0) fprintf(fp, "\n   ");
+      fprintf(fp, "0x%02x, ", quantRB[i]);
+   }
+   fprintf(fp, "\n};\n\n");
+
+   fprintf(fp,
+           "static const unsigned char quantG[256 + 16] =\n"
+           "{");
+   for(i = 0; i < 256 + 16; ++i)
+   {
+      if(i % 8 == 0) fprintf(fp, "\n   ");
+      fprintf(fp, "0x%02x, ", quantG[i]);
+   }
+   fprintf(fp, "\n};\n\n");
+   
+   prepare_opt_table(&omatch5[0][0], expand5, 32);
+   prepare_opt_table(&omatch6[0][0], expand6, 64);
+   
+   fprintf(fp,
+           "static const unsigned char omatch5[256][2] =\n"
+           "{");
+   for(i = 0; i < 256; ++i)
+   {
+      if(i % 4 == 0) fprintf(fp, "\n   ");
+      fprintf(fp, "{0x%02x, 0x%02x}, ", omatch5[i][0], omatch5[i][1]);
+   }
+   fprintf(fp, "\n};\n\n");
+
+   fprintf(fp,
+           "static const unsigned char omatch6[256][2] =\n"
+           "{");
+   for(i = 0; i < 256; ++i)
+   {
+      if(i % 4 == 0) fprintf(fp, "\n   ");
+      fprintf(fp, "{0x%02x, 0x%02x}, ", omatch6[i][0], omatch6[i][1]);
+   }
+   fprintf(fp, "\n};\n\n");
+   
+   fprintf(fp, "#endif\n");
+   
+   fclose(fp);
+   
+   return(0);
+}
+#endif