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-rw-r--r--arch/s390/lib/Makefile2
-rw-r--r--arch/s390/lib/find.c77
2 files changed, 78 insertions, 1 deletions
diff --git a/arch/s390/lib/Makefile b/arch/s390/lib/Makefile
index 20b0e97a7df2..e506c5fb6f6a 100644
--- a/arch/s390/lib/Makefile
+++ b/arch/s390/lib/Makefile
@@ -2,7 +2,7 @@
# Makefile for s390-specific library files..
#
-lib-y += delay.o string.o uaccess_std.o uaccess_pt.o
+lib-y += delay.o string.o uaccess_std.o uaccess_pt.o find.o
obj-$(CONFIG_32BIT) += div64.o qrnnd.o ucmpdi2.o mem32.o
obj-$(CONFIG_64BIT) += mem64.o
lib-$(CONFIG_64BIT) += uaccess_mvcos.o
diff --git a/arch/s390/lib/find.c b/arch/s390/lib/find.c
new file mode 100644
index 000000000000..8963929b06b9
--- /dev/null
+++ b/arch/s390/lib/find.c
@@ -0,0 +1,77 @@
+/*
+ * MSB0 numbered special bitops handling.
+ *
+ * On s390x the bits are numbered:
+ * |0..............63|64............127|128...........191|192...........255|
+ * and on s390:
+ * |0.....31|31....63|64....95|96...127|128..159|160..191|192..223|224..255|
+ *
+ * The reason for this bit numbering is the fact that the hardware sets bits
+ * in a bitmap starting at bit 0 (MSB) and we don't want to scan the bitmap
+ * from the 'wrong end'.
+ */
+
+#include <linux/compiler.h>
+#include <linux/bitops.h>
+#include <linux/export.h>
+
+unsigned long find_first_bit_left(const unsigned long *addr, unsigned long size)
+{
+ const unsigned long *p = addr;
+ unsigned long result = 0;
+ unsigned long tmp;
+
+ while (size & ~(BITS_PER_LONG - 1)) {
+ if ((tmp = *(p++)))
+ goto found;
+ result += BITS_PER_LONG;
+ size -= BITS_PER_LONG;
+ }
+ if (!size)
+ return result;
+ tmp = (*p) & (~0UL << (BITS_PER_LONG - size));
+ if (!tmp) /* Are any bits set? */
+ return result + size; /* Nope. */
+found:
+ return result + (__fls(tmp) ^ (BITS_PER_LONG - 1));
+}
+EXPORT_SYMBOL(find_first_bit_left);
+
+unsigned long find_next_bit_left(const unsigned long *addr, unsigned long size,
+ unsigned long offset)
+{
+ const unsigned long *p = addr + (offset / BITS_PER_LONG);
+ unsigned long result = offset & ~(BITS_PER_LONG - 1);
+ unsigned long tmp;
+
+ if (offset >= size)
+ return size;
+ size -= result;
+ offset %= BITS_PER_LONG;
+ if (offset) {
+ tmp = *(p++);
+ tmp &= (~0UL >> offset);
+ if (size < BITS_PER_LONG)
+ goto found_first;
+ if (tmp)
+ goto found_middle;
+ size -= BITS_PER_LONG;
+ result += BITS_PER_LONG;
+ }
+ while (size & ~(BITS_PER_LONG-1)) {
+ if ((tmp = *(p++)))
+ goto found_middle;
+ result += BITS_PER_LONG;
+ size -= BITS_PER_LONG;
+ }
+ if (!size)
+ return result;
+ tmp = *p;
+found_first:
+ tmp &= (~0UL << (BITS_PER_LONG - size));
+ if (!tmp) /* Are any bits set? */
+ return result + size; /* Nope. */
+found_middle:
+ return result + (__fls(tmp) ^ (BITS_PER_LONG - 1));
+}
+EXPORT_SYMBOL(find_next_bit_left);