* .version: changed version to 2.5.4

[fw/sdcc] / device / lib / pic / libsdcc / _moduchar.c

diff --git a/device/lib/pic/libsdcc/_moduchar.c b/device/lib/pic/libsdcc/_moduchar.c
new file mode 100644 (file)
index 0000000..402002e
--- /dev/null
+++ b/device/lib/pic/libsdcc/_moduchar.c
@@ -0,0 +1,54 @@
+/* ---------------------------------------------------------------------------
+   _moduchar.c : 8 bit modulus routines for pic14 devices
+
+       Written By      Raphael Neider, rneider@web.de (2005)
+
+   This library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public
+   License as published by the Free Software Foundation; either
+   version 2 of the License, or (at your option) any later version.
+
+   This library 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
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with this library; if not, write to the 
+   Free Software Foundation, Inc., 59 Temple Place - Suite 330, 
+   Boston, MA  02111-1307  USA.
+
+   In other words, you are welcome to use, share and improve this program.
+   You are forbidden to forbid anyone else to use, share and improve
+   what you give them.   Help stamp out software-hoarding!
+
+   $Id$
+   ------------------------------------------------------------------------ */
+
+unsigned char
+_moduchar (unsigned char a, unsigned char b)
+{
+  unsigned char count = 1;
+
+  /* prevent endless loop (division by zero exception?!?) */
+  if (!b) return (unsigned char)-1;
+
+  /* it would suffice to make b >= a, but that test is
+   * more complex and will fail if a has its MSB set */
+  while (!(b & (1UL << (8*sizeof(unsigned char)-1)))) {
+    b <<= 1;
+    ++count;
+  } // while
+
+  /* now subtract all the powers of two (of b) that "fit" into a */
+  while (count) {
+    if (a >= b) {
+      a -= b;
+    } // if
+    b >>= 1;
+    --count;
+  } // while
+
+  return a;
+}
+