Imported Upstream version 4.3.99+cvs20050702

1 files changed, 85 insertions, 0 deletions

diff --git a/src/main/dither-inlined-functions.h b/src/main/dither-inlined-functions.h
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+++ b/src/main/dither-inlined-functions.h
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+/*
+ * "$Id: dither-inlined-functions.h,v 1.6 2004/09/17 18:38:18 rleigh Exp $"
+ *
+ *   Performance-critical functions that should be inlined, based on
+ *   measurements.
+ *
+ *   Copyright 1997-2003 Michael Sweet (mike@easysw.com) and
+ *	Robert Krawitz (rlk@alum.mit.edu)
+ *
+ *   This program 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 2 of the License, or (at your option)
+ *   any later version.
+ *
+ *   This program 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.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Revision History:
+ *
+ *   See ChangeLog
+ */
+
+#ifndef GUTENPRINT_INTERNAL_DITHER_INLINED_FUNCTIONS_H
+#define GUTENPRINT_INTERNAL_DITHER_INLINED_FUNCTIONS_H
+
+/*
+ * Inlining has yielded significant (measured) speedup, even with the
+ * more complicated dither function. --rlk 20011219
+ */
+
+static inline unsigned
+ditherpoint(const stpi_dither_t *d, stp_dither_matrix_impl_t *mat, int x)
+{
+  if (mat->fast_mask)
+    return mat->matrix[(mat->last_y_mod +
+			((x + mat->x_offset) & mat->fast_mask))];
+  /*
+   * This rather bizarre code is an attempt to avoid having to compute a lot
+   * of modulus and multiplication operations, which are typically slow.
+   */
+
+  if (x == mat->last_x + 1)
+    {
+      mat->last_x_mod++;
+      mat->index++;
+      if (mat->last_x_mod >= mat->x_size)
+	{
+	  mat->last_x_mod -= mat->x_size;
+	  mat->index -= mat->x_size;
+	}
+    }
+  else if (x == mat->last_x - 1)
+    {
+      mat->last_x_mod--;
+      mat->index--;
+      if (mat->last_x_mod < 0)
+	{
+	  mat->last_x_mod += mat->x_size;
+	  mat->index += mat->x_size;
+	}
+    }
+  else if (x != mat->last_x)
+    {
+      mat->last_x_mod = (x + mat->x_offset) % mat->x_size;
+      mat->index = mat->last_x_mod + mat->last_y_mod;
+    }
+  mat->last_x = x;
+  return mat->matrix[mat->index];
+}
+
+static inline void
+set_row_ends(stpi_dither_channel_t *dc, int x)
+{
+  if (dc->row_ends[0] == -1)
+    dc->row_ends[0] = x;
+  dc->row_ends[1] = x;
+}
+
+#endif /* GUTENPRINT_INTERNAL_DITHER_INLINED_FUNCTIONS_H */