sdcc-3.9.0 fork implementing GNU assembler syntax

This fork aims to provide better support for stm8-binutils

1 files changed, 57 insertions, 0 deletions

diff --git a/device/lib/rand.c b/device/lib/rand.c
new file mode 100644
index 0000000..7794f2d
--- /dev/null
+++ b/device/lib/rand.c
@@ -0,0 +1,57 @@
+/*-------------------------------------------------------------------------
+   rand.c - random number generator
+
+   Copyright (C) 2017, Philipp Klaus Krause, pkk@spth.de
+
+   This library 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, 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this library; see the file COPYING. If not, write to the
+   Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
+   MA 02110-1301, USA.
+
+   As a special exception, if you link this library with other files,
+   some of which are compiled with SDCC, to produce an executable,
+   this library does not by itself cause the resulting executable to
+   be covered by the GNU General Public License. This exception does
+   not however invalidate any other reasons why the executable file
+   might be covered by the GNU General Public License.
+
+   This is an xorshift PRNG. See George Marsaglia, "Xorshift RNGs" for details.
+   The width of 32 bits was chosen to not regress in period length vs. the
+   PRNG from the C standard, while at the same time minimizing RAM usage.
+   The parameters a, b, c were chosen to allow the generation of efficient code.
+-------------------------------------------------------------------------*/
+
+#include <stdlib.h>
+
+#include <stdint.h>
+
+static uint32_t s = 0x80000001;
+
+int rand(void)
+{
+	register unsigned long t = s;
+
+	t ^= t >> 10;
+	t ^= t << 9;
+	t ^= t >> 25;
+
+	s = t;
+
+	return(t & RAND_MAX);
+}
+
+void srand(unsigned int seed)
+{
+    s = seed | 0x80000000; /* s shall not become 0 */
+}
+