--- /dev/null
+/* Copyright (C) 2003, 2009 Free Software Foundation, Inc.
+
+This file is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by the
+Free Software Foundation; either version 3, or (at your option) any
+later version.
+
+This file is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+General Public License for more details.
+
+Under Section 7 of GPL version 3, you are granted additional
+permissions described in the GCC Runtime Library Exception, version
+3.1, as published by the Free Software Foundation.
+
+You should have received a copy of the GNU General Public License and
+a copy of the GCC Runtime Library Exception along with this program;
+see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+<http://www.gnu.org/licenses/>. */
+
+
+/* Calculate division table for SH5Media integer division
+ Contributed by Joern Rennecke
+ joern.rennecke@superh.com */
+
+#include <stdio.h>
+#include <math.h>
+
+#define BITS 5
+#define N_ENTRIES (1 << BITS)
+#define CUTOFF_BITS 20
+
+#define BIAS (-330)
+
+double max_defect = 0.;
+double max_defect_x;
+
+double min_defect = 1e9;
+double min_defect_x;
+
+double max_defect2 = 0.;
+double max_defect2_x;
+
+double min_defect2 = 0.;
+double min_defect2_x;
+
+double min_defect3 = 01e9;
+double min_defect3_x;
+int min_defect3_val;
+
+double max_defect3 = 0.;
+double max_defect3_x;
+int max_defect3_val;
+
+static double note_defect3 (int val, double d2, double y2d, double x)
+{
+ int cutoff_val = val >> CUTOFF_BITS;
+ double cutoff;
+ double defect;
+
+ if (val < 0)
+ cutoff_val++;
+ cutoff = (cutoff_val * (1<<CUTOFF_BITS) - val) * y2d;
+ defect = cutoff + val * d2;
+ if (val < 0)
+ defect = - defect;
+ if (defect > max_defect3)
+ {
+ max_defect3 = defect;
+ max_defect3_x = x;
+ max_defect3_val = val;
+ }
+ if (defect < min_defect3)
+ {
+ min_defect3 = defect;
+ min_defect3_x = x;
+ min_defect3_val = val;
+ }
+}
+
+/* This function assumes 32-bit integers. */
+static double
+calc_defect (double x, int constant, int factor)
+{
+ double y0 = (constant - (int) floor ((x * factor * 64.))) / 16384.;
+ double y1 = 2 * y0 -y0 * y0 * (x + BIAS / (1.*(1LL<<30)));
+ double y2d0, y2d;
+ int y2d1;
+ double d, d2;
+
+ y1 = floor (y1 * (1024 * 1024 * 1024)) / (1024 * 1024 * 1024);
+ d = y1 - 1 / x;
+ if (d > max_defect)
+ {
+ max_defect = d;
+ max_defect_x = x;
+ }
+ if (d < min_defect)
+ {
+ min_defect = d;
+ min_defect_x = x;
+ }
+ y2d0 = floor (y1 * x * (1LL << 60-16));
+ y2d1 = (int) (long long) y2d0;
+ y2d = - floor ((y1 - y0 / (1<<30-14)) * y2d1) / (1LL<<44);
+ d2 = y1 + y2d - 1/x;
+ if (d2 > max_defect2)
+ {
+ max_defect2 = d2;
+ max_defect2_x = x;
+ }
+ if (d2 < min_defect2)
+ {
+ min_defect2 = d2;
+ min_defect2_x = x;
+ }
+ /* zero times anything is trivially zero. */
+ note_defect3 ((1 << CUTOFF_BITS) - 1, d2, y2d, x);
+ note_defect3 (1 << CUTOFF_BITS, d2, y2d, x);
+ note_defect3 ((1U << 31) - (1 << CUTOFF_BITS), d2, y2d, x);
+ note_defect3 ((1U << 31) - 1, d2, y2d, x);
+ note_defect3 (-1, d2, y2d, x);
+ note_defect3 (-(1 << CUTOFF_BITS), d2, y2d, x);
+ note_defect3 ((1U << 31) - (1 << CUTOFF_BITS) + 1, d2, y2d, x);
+ note_defect3 (-(1U << 31), d2, y2d, x);
+ return d;
+}
+
+int
+main ()
+{
+ int i;
+ unsigned char factors[N_ENTRIES];
+ short constants[N_ENTRIES];
+ int steps = N_ENTRIES / 2;
+ double step = 1. / steps;
+ double eps30 = 1. / (1024 * 1024 * 1024);
+
+ for (i = 0; i < N_ENTRIES; i++)
+ {
+ double x_low = (i < steps ? 1. : -3.) + i * step;
+ double x_high = x_low + step - eps30;
+ double x_med;
+ int factor, constant;
+ double low_defect, med_defect, high_defect, max_defect;
+
+ factor = (1./x_low- 1./x_high) / step * 256. + 0.5;
+ if (factor == 256)
+ factor = 255;
+ factors[i] = factor;
+ /* Use minimum of error function for x_med. */
+ x_med = sqrt (256./factor);
+ if (x_low < 0)
+ x_med = - x_med;
+ low_defect = 1. / x_low + x_low * factor / 256.;
+ high_defect = 1. / x_high + x_high * factor / 256.;
+ med_defect = 1. / x_med + x_med * factor / 256.;
+ max_defect
+ = ((low_defect > high_defect) ^ (x_med < 0)) ? low_defect : high_defect;
+ constant = (med_defect + max_defect) * 0.5 * 16384. + 0.5;
+ if (constant < -32768 || constant > 32767)
+ abort ();
+ constants[i] = constant;
+ calc_defect (x_low, constant, factor);
+ calc_defect (x_med, constant, factor);
+ calc_defect (x_high, constant, factor);
+ }
+ printf ("/* This table has been generated by divtab.c .\n");
+ printf ("Defects for bias %d:\n", BIAS);
+ printf (" Max defect: %e at %e\n", max_defect, max_defect_x);
+ printf (" Min defect: %e at %e\n", min_defect, min_defect_x);
+ printf (" Max 2nd step defect: %e at %e\n", max_defect2, max_defect2_x);
+ printf (" Min 2nd step defect: %e at %e\n", min_defect2, min_defect2_x);
+ printf (" Max div defect: %e at %d:%e\n", max_defect3, max_defect3_val, max_defect3_x);
+ printf (" Min div defect: %e at %d:%e\n", min_defect3, min_defect3_val, min_defect3_x);
+ printf (" Defect at 1: %e\n",
+ calc_defect (1., constants[0], factors[0]));
+ printf (" Defect at -2: %e */\n",
+ calc_defect (-2., constants[steps], factors[steps]));
+ printf ("\t.section\t.rodata\n");
+ printf ("\t.balign 2\n");
+ printf ("/* negative division constants */\n");
+ for (i = steps; i < 2 * steps; i++)
+ printf ("\t.word\t%d\n", constants[i]);
+ printf ("/* negative division factors */\n");
+ for (i = steps; i < 2*steps; i++)
+ printf ("\t.byte\t%d\n", factors[i]);
+ printf ("\t.skip %d\n", steps);
+ printf ("\t.global GLOBAL(div_table):\n");
+ printf ("GLOBAL(div_table):\n");
+ printf ("\t.skip %d\n", steps);
+ printf ("/* positive division factors */\n");
+ for (i = 0; i < steps; i++)
+ printf ("\t.byte\t%d\n", factors[i]);
+ printf ("/* positive division constants */\n");
+ for (i = 0; i < steps; i++)
+ printf ("\t.word\t%d\n", constants[i]);
+ exit (0);
+}
projects / msp430-gcc.git / blobdiff