aboutsummaryrefslogtreecommitdiff
path: root/sysdeps/s390/ffs.c
diff options
context:
space:
mode:
Diffstat (limited to 'sysdeps/s390/ffs.c')
-rw-r--r--sysdeps/s390/ffs.c68
1 files changed, 68 insertions, 0 deletions
diff --git a/sysdeps/s390/ffs.c b/sysdeps/s390/ffs.c
new file mode 100644
index 0000000000..b6ed821e58
--- /dev/null
+++ b/sysdeps/s390/ffs.c
@@ -0,0 +1,68 @@
+/* ffs -- find first set bit in a word, counted from least significant end.
+ This file is part of the GNU C Library.
+ Copyright (C) 2000 Free Software Foundation, Inc.
+ Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com).
+
+ The GNU C 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.
+
+ The GNU C 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 the GNU C Library; see the file COPYING.LIB. If not,
+ write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA. */
+
+#define ffsl __something_else
+#include <string.h>
+
+#undef ffs
+
+/*
+ * ffs: find first bit set. This is defined the same way as
+ * the libc and compiler builtin ffs routines, therefore
+ * differs in spirit from the above ffz (man ffs).
+ */
+
+int
+__ffs (x)
+ int x;
+{
+ int r;
+
+ if (x == 0)
+ return 0;
+ __asm__(" lr %%r1,%1\n"
+ " sr %0,%0\n"
+ " tml %%r1,0xFFFF\n"
+ " jnz 0f\n"
+ " ahi %0,16\n"
+ " srl %%r1,16\n"
+ "0: tml %%r1,0x00FF\n"
+ " jnz 1f\n"
+ " ahi %0,8\n"
+ " srl %%r1,8\n"
+ "1: tml %%r1,0x000F\n"
+ " jnz 2f\n"
+ " ahi %0,4\n"
+ " srl %%r1,4\n"
+ "2: tml %%r1,0x0003\n"
+ " jnz 3f\n"
+ " ahi %0,2\n"
+ " srl %%r1,2\n"
+ "3: tml %%r1,0x0001\n"
+ " jnz 4f\n"
+ " ahi %0,1\n"
+ "4:"
+ : "=&d" (r) : "d" (x) : "cc", "1" );
+ return r+1;
+}
+
+weak_alias (__ffs, ffs)
+#undef ffsl
+weak_alias (__ffs, ffsl)