--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/video/Xext/XmuStdCmap/CmapAlloc.c	Thu Jul 12 20:00:50 2007 +0000
@@ -0,0 +1,337 @@
+/* $Xorg: CmapAlloc.c,v 1.4 2001/02/09 02:03:51 xorgcvs Exp $ */
+
+/* 
+
+Copyright 1989, 1994, 1998  The Open Group
+
+Permission to use, copy, modify, distribute, and sell this software and its
+documentation for any purpose is hereby granted without fee, provided that
+the above copyright notice appear in all copies and that both that
+copyright notice and this permission notice appear in supporting
+documentation.
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+Except as contained in this notice, the name of The Open Group shall not be
+used in advertising or otherwise to promote the sale, use or other dealings
+in this Software without prior written authorization from The Open Group.
+
+*/
+/* $XFree86: xc/lib/Xmu/CmapAlloc.c,v 1.6 2001/01/17 19:42:53 dawes Exp $ */
+
+/*
+ * Author:  Donna Converse, MIT X Consortium
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+#include <X11/Xlib.h>
+#include <X11/Xatom.h>
+#include <X11/Xutil.h>
+#include "../extensions/StdCmap.h"
+#include <stdio.h>
+
+#define lowbit(x) ((x) & (~(x) + 1))
+
+/*
+ * Prototypes
+ */
+static void best_allocation(XVisualInfo *, unsigned long *, unsigned long *,
+                            unsigned long *);
+static int default_allocation(XVisualInfo *, unsigned long *,
+                              unsigned long *, unsigned long *);
+static void gray_allocation(int, unsigned long *, unsigned long *,
+                            unsigned long *);
+static int icbrt(int);
+static int icbrt_with_bits(int, int);
+static int icbrt_with_guess(int, int);
+
+/* To determine the best allocation of reds, greens, and blues in a 
+ * standard colormap, use XmuGetColormapAllocation.
+ * 	vinfo		specifies visual information for a chosen visual
+ *	property	specifies one of the standard colormap property names
+ * 	red_max		returns maximum red value 
+ *      green_max	returns maximum green value
+ * 	blue_max	returns maximum blue value
+ *
+ * XmuGetColormapAllocation returns 0 on failure, non-zero on success.
+ * It is assumed that the visual is appropriate for the colormap property.
+ */
+
+Status
+XmuGetColormapAllocation(XVisualInfo * vinfo, Atom property,
+                         unsigned long *red_max,
+                         unsigned long *green_max, unsigned long *blue_max)
+{
+    Status status = 1;
+
+    if (vinfo->colormap_size <= 2)
+        return 0;
+
+    switch (property) {
+    case XA_RGB_DEFAULT_MAP:
+        status = default_allocation(vinfo, red_max, green_max, blue_max);
+        break;
+    case XA_RGB_BEST_MAP:
+        best_allocation(vinfo, red_max, green_max, blue_max);
+        break;
+    case XA_RGB_GRAY_MAP:
+        gray_allocation(vinfo->colormap_size, red_max, green_max, blue_max);
+        break;
+    case XA_RGB_RED_MAP:
+        *red_max = vinfo->colormap_size - 1;
+        *green_max = *blue_max = 0;
+        break;
+    case XA_RGB_GREEN_MAP:
+        *green_max = vinfo->colormap_size - 1;
+        *red_max = *blue_max = 0;
+        break;
+    case XA_RGB_BLUE_MAP:
+        *blue_max = vinfo->colormap_size - 1;
+        *red_max = *green_max = 0;
+        break;
+    default:
+        status = 0;
+    }
+    return status;
+}
+
+/****************************************************************************/
+/* Determine the appropriate color allocations of a gray scale.
+ *
+ * Keith Packard, MIT X Consortium
+ */
+
+static void
+gray_allocation(int n, unsigned long *red_max, unsigned long *green_max,
+                unsigned long *blue_max)
+{
+    *red_max = (n * 30) / 100;
+    *green_max = (n * 59) / 100;
+    *blue_max = (n * 11) / 100;
+    *green_max += ((n - 1) - (*red_max + *green_max + *blue_max));
+}
+
+/****************************************************************************/
+/* Determine an appropriate color allocation for the RGB_DEFAULT_MAP.
+ * If a map has less than a minimum number of definable entries, we do not
+ * produce an allocation for an RGB_DEFAULT_MAP.  
+ *
+ * For 16 planes, the default colormap will have 27 each RGB; for 12 planes,
+ * 12 each.  For 8 planes, let n = the number of colormap entries, which may
+ * be 256 or 254.  Then, maximum red value = floor(cube_root(n - 125)) - 1.
+ * Maximum green and maximum blue values are identical to maximum red.
+ * This leaves at least 125 cells which clients can allocate.
+ *
+ * Return 0 if an allocation has been determined, non-zero otherwise.
+ */
+
+static int
+default_allocation(XVisualInfo * vinfo, unsigned long *red,
+                   unsigned long *green, unsigned long *blue)
+{
+    int ngrays;                 /* number of gray cells */
+
+    switch (vinfo->class) {
+    case PseudoColor:
+
+        if (vinfo->colormap_size > 65000)
+            /* intended for displays with 16 planes */
+            *red = *green = *blue = (unsigned long) 27;
+        else if (vinfo->colormap_size > 4000)
+            /* intended for displays with 12 planes */
+            *red = *green = *blue = (unsigned long) 12;
+        else if (vinfo->colormap_size < 250)
+            return 0;
+        else
+            /* intended for displays with 8 planes */
+            *red = *green = *blue = (unsigned long)
+                (icbrt(vinfo->colormap_size - 125) - 1);
+        break;
+
+    case DirectColor:
+
+        if (vinfo->colormap_size < 10)
+            return 0;
+        *red = *green = *blue = vinfo->colormap_size / 2 - 1;
+        break;
+
+    case TrueColor:
+
+        *red = vinfo->red_mask / lowbit(vinfo->red_mask);
+        *green = vinfo->green_mask / lowbit(vinfo->green_mask);
+        *blue = vinfo->blue_mask / lowbit(vinfo->blue_mask);
+        break;
+
+    case GrayScale:
+
+        if (vinfo->colormap_size > 65000)
+            ngrays = 4096;
+        else if (vinfo->colormap_size > 4000)
+            ngrays = 512;
+        else if (vinfo->colormap_size < 250)
+            return 0;
+        else
+            ngrays = 12;
+        gray_allocation(ngrays, red, green, blue);
+        break;
+
+    default:
+        return 0;
+    }
+    return 1;
+}
+
+/****************************************************************************/
+/* Determine an appropriate color allocation for the RGB_BEST_MAP.
+ *
+ * For a DirectColor or TrueColor visual, the allocation is determined
+ * by the red_mask, green_mask, and blue_mask members of the visual info.
+ *
+ * Otherwise, if the colormap size is an integral power of 2, determine
+ * the allocation according to the number of bits given to each color,
+ * with green getting more than red, and red more than blue, if there
+ * are to be inequities in the distribution.  If the colormap size is
+ * not an integral power of 2, let n = the number of colormap entries.
+ * Then maximum red value = floor(cube_root(n)) - 1;
+ * 	maximum blue value = floor(cube_root(n)) - 1;
+ *	maximum green value = n / ((# red values) * (# blue values)) - 1;
+ * Which, on a GPX, allows for 252 entries in the best map, out of 254
+ * defineable colormap entries.
+ */
+
+static void
+best_allocation(XVisualInfo * vinfo, unsigned long *red, unsigned long *green,
+                unsigned long *blue)
+{
+
+    if (vinfo->class == DirectColor || vinfo->class == TrueColor) {
+        *red = vinfo->red_mask;
+        while ((*red & 01) == 0)
+            *red >>= 1;
+        *green = vinfo->green_mask;
+        while ((*green & 01) == 0)
+            *green >>= 1;
+        *blue = vinfo->blue_mask;
+        while ((*blue & 01) == 0)
+            *blue >>= 1;
+    } else {
+        register int bits, n;
+
+        /* Determine n such that n is the least integral power of 2 which is
+         * greater than or equal to the number of entries in the colormap.
+         */
+        n = 1;
+        bits = 0;
+        while (vinfo->colormap_size > n) {
+            n = n << 1;
+            bits++;
+        }
+
+        /* If the number of entries in the colormap is a power of 2, determine
+         * the allocation by "dealing" the bits, first to green, then red, then
+         * blue.  If not, find the maximum integral red, green, and blue values
+         * which, when multiplied together, do not exceed the number of 
+
+         * colormap entries.
+         */
+        if (n == vinfo->colormap_size) {
+            register int r, g, b;
+            b = bits / 3;
+            g = b + ((bits % 3) ? 1 : 0);
+            r = b + (((bits % 3) == 2) ? 1 : 0);
+            *red = 1 << r;
+            *green = 1 << g;
+            *blue = 1 << b;
+        } else {
+            *red = icbrt_with_bits(vinfo->colormap_size, bits);
+            *blue = *red;
+            *green = (vinfo->colormap_size / ((*red) * (*blue)));
+        }
+        (*red)--;
+        (*green)--;
+        (*blue)--;
+    }
+    return;
+}
+
+/*
+ * integer cube roots by Newton's method
+ *
+ * Stephen Gildea, MIT X Consortium, July 1991
+ */
+
+static int
+icbrt(int a)
+{
+    register int bits = 0;
+    register unsigned n = a;
+
+    while (n) {
+        bits++;
+        n >>= 1;
+    }
+    return icbrt_with_bits(a, bits);
+}
+
+
+static int
+icbrt_with_bits(int a, int bits)
+     /* bits - log 2 of a */
+{
+    return icbrt_with_guess(a, a >> 2 * bits / 3);
+}
+
+#ifdef _X_ROOT_STATS
+int icbrt_loopcount;
+#endif
+
+/* Newton's Method:  x_n+1 = x_n - ( f(x_n) / f'(x_n) ) */
+
+/* for cube roots, x^3 - a = 0,  x_new = x - 1/3 (x - a/x^2) */
+
+/*
+ * Quick and dirty cube roots.  Nothing fancy here, just Newton's method.
+ * Only works for positive integers (since that's all we need).
+ * We actually return floor(cbrt(a)) because that's what we need here, too.
+ */
+
+static int
+icbrt_with_guess(int a, int guess)
+{
+    register int delta;
+
+#ifdef _X_ROOT_STATS
+    icbrt_loopcount = 0;
+#endif
+    if (a <= 0)
+        return 0;
+    if (guess < 1)
+        guess = 1;
+
+    do {
+#ifdef _X_ROOT_STATS
+        icbrt_loopcount++;
+#endif
+        delta = (guess - a / (guess * guess)) / 3;
+#ifdef DEBUG
+        printf("pass %d: guess=%d, delta=%d\n", icbrt_loopcount, guess,
+               delta);
+#endif
+        guess -= delta;
+    } while (delta != 0);
+
+    if (guess * guess * guess > a)
+        guess--;
+
+    return guess;
+}