--- OLD/pnm/xwdtopnm.c	Thu Jan  1 00:00:00 1970
+++ NEW/pnm/xwdtopnm.c	Thu Jan  1 00:00:00 1970
@@ -20,6 +20,11 @@
 static long bs_long ARGS(( long l ));
 
 static unsigned long red_mask, green_mask, blue_mask;
+static int red_shift, green_shift, blue_shift;
+static unsigned long red_mul, green_mul, blue_mul;
+static int red_amshift, green_amshift, blue_amshift;
+static long int maxval;
+static int fast_truedirect;
 static int bits_per_item, bits_used, bit_shift, bits_per_pixel;
 static char buf[4];
 static char* byteP;
@@ -28,6 +33,86 @@
 static unsigned long pixel_mask;
 static int byte_swap, byte_order, bit_order;
 
+static int mask_shift_count(unsigned long int mask)
+{
+ int i;
+
+ for (i=0;!(mask&1);i++,mask>>=1) ;
+ return(i);
+}
+
+static void compute_truedirect_values(void)
+{
+ unsigned long int rm;
+ unsigned long int gm;
+ unsigned long int bm;
+ unsigned long int m;
+ int rw;
+ int gw;
+ int bw;
+ int w;
+ unsigned long int f;
+ unsigned long int a;
+ unsigned long int s;
+
+ rm = red_mask >> red_shift;
+ gm = green_mask >> green_shift;
+ bm = blue_mask >> blue_shift;
+ fast_truedirect = ((rm == gm) && (rm == bm) && (rm <= PNM_MAXMAXVAL));
+ if (fast_truedirect)
+  { maxval = rm;
+    return;
+  }
+ m = PNM_MAXMAXVAL;
+ red_mul = 1;
+ red_amshift = 0;
+ green_mul = 1;
+ green_amshift = 0;
+ blue_mul = 1;
+ blue_amshift = 0;
+ if (rm > m) for (;rm>m;red_amshift++,rm>>=1) ;
+ if (gm > m) for (;gm>m;green_amshift++,gm>>=1) ;
+ if (bm > m) for (;bm>m;blue_amshift++,bm>>=1) ;
+ m = rm | gm | bm;
+ if (rm < m)
+  { for (f=rm,s=0;f;s++,f>>=1) ;
+    a = 1;
+    f = 1;
+    while (rm < m)
+     { a <<= s;
+       f += a;
+       rm |= rm << s;
+     }
+    red_mul = f;
+    for (;rm>m;red_amshift++,rm>>=1) ;
+  }
+ if (gm < m)
+  { for (f=gm,s=0;f;s++,f>>=1) ;
+    a = 1;
+    f = 1;
+    while (gm < m)
+     { a <<= s;
+       f += a;
+       gm |= gm << s;
+     }
+    green_mul = f;
+    for (;gm>m;green_amshift++,gm>>=1) ;
+  }
+ if (bm < m)
+  { for (f=bm,s=0;f;s++,f>>=1) ;
+    a = 1;
+    f = 1;
+    while (bm < m)
+     { a <<= s;
+       f += a;
+       bm |= bm << s;
+     }
+    blue_mul = f;
+    for (;bm>m;blue_amshift++,bm>>=1) ;
+  }
+ maxval = m;
+}
+
 int
 main( argc, argv )
     int argc;
@@ -39,7 +124,7 @@
     xel* colors;
     int rows, cols, format, padright, row;
     register int col;
-    long maxval, visualclass;
+    long int visualclass;
 
     pnm_init( &argc, argv );
 
@@ -53,6 +138,14 @@
 
     getinit( ifp, &cols, &rows, &padright, &maxval, &visualclass, &format, &colors );
 
+    switch ( visualclass )
+	{
+	case TrueColor:
+	case DirectColor:
+	compute_truedirect_values();
+	break;
+	}
+
     pnm_writepnminit( stdout, cols, rows, (xelval) maxval, format, 0 );
     xelrow = pnm_allocrow( cols );
     switch ( PNM_FORMAT_TYPE(format) )
@@ -89,28 +182,18 @@
             case DirectColor:
 	    for ( col = 0, xP = xelrow; col < cols; ++col, ++xP )
 		{
-		register unsigned long ul;
-
-		ul = getpixnum( ifp );
-		switch ( bits_per_pixel )
-		    {
-		    case 16:
+		unsigned long int v;
+		v = getpixnum(ifp);
+		if (fast_truedirect)
 		    PPM_ASSIGN( *xP,
-			( ( ul & red_mask ) >> 0 ),
-			( ( ul & green_mask ) >> 5 ),
-			( ( ul & blue_mask ) >> 10 ) );
-		    break;
-
-		    case 24:
-		    case 32:
-		    PPM_ASSIGN( *xP, ( ( ul & 0xff0000 ) >> 16 ),
-			( ( ul & 0xff00 ) >> 8 ),
-			( ul & 0xff ) );
-		    break;
-
-		    default:
-		    pm_error( "True/Direct only supports 16, 24, and 32 bits" );
-		    }
+				(v &   red_mask) >>   red_shift,
+				(v & green_mask) >> green_shift,
+				(v &  blue_mask) >>  blue_shift );
+		else
+		    PPM_ASSIGN( *xP,
+	(((v &   red_mask) >>   red_shift) *   red_mul) >>   red_amshift,
+	(((v & green_mask) >> green_shift) * green_mul) >> green_amshift,
+	(((v &  blue_mask) >>  blue_shift) *  blue_mul) >>  blue_amshift );
 		}
 	    break;
 
@@ -385,13 +468,19 @@
 	        *maxvalP = 31;
             else
 		*maxvalP = 255;
+	    red_mask = h11P->red_mask;
+	    green_mask = h11P->green_mask;
+	    blue_mask = h11P->blue_mask;
+	    red_shift = mask_shift_count(red_mask);
+	    green_shift = mask_shift_count(green_mask);
+	    blue_shift = mask_shift_count(blue_mask);
 	    }
 	else if ( *visualclassP == StaticGray && h11P->bits_per_pixel == 1 )
 	    {
 	    *formatP = PBM_TYPE;
 	    *maxvalP = 1;
 	    *colorsP = pnm_allocrow( 2 );
-	    PNM_ASSIGN1( (*colorsP)[0], *maxvalP );
+	    PNM_ASSIGN1( (*colorsP)[0], 1 );
 	    PNM_ASSIGN1( (*colorsP)[1], 0 );
 	    }
 	else if ( *visualclassP == StaticGray )
@@ -435,9 +524,6 @@
 	    pixel_mask = -1;
 	else
 	    pixel_mask = ( 1 << bits_per_pixel ) - 1;
-        red_mask = h11P->red_mask;
-        green_mask = h11P->green_mask;
-        blue_mask = h11P->blue_mask;
 	}
     else
 	pm_error( "unknown XWD file version: %d", h11P->file_version );