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authorHeiko Carstens <hca@linux.ibm.com>2023-10-06 15:42:41 +0200
committerVasily Gorbik <gor@linux.ibm.com>2023-10-16 13:04:09 +0200
commit76292d7243f809486ec26dd6cd3436dbcb9e5319 (patch)
treeed94521d81a64c9e2e17d68da82a0b800516d1cb /arch/s390/include
parent88b2c332fcecbcf71a5d69a214a8805cf916fbf8 (diff)
s390: provide word-at-a-time implementation
Provide an s390 specific word-at-a-time implementation. Compared to the generic variant the generated code for has_zero() is slightly better. However find_zero() is much simpler since it reuses the result of __fls() aka flogr() and now comes without any conditional branches, while the generic variant has three of them. Reviewed-by: Sven Schnelle <svens@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch/s390/include')
-rw-r--r--arch/s390/include/asm/word-at-a-time.h42
1 files changed, 42 insertions, 0 deletions
diff --git a/arch/s390/include/asm/word-at-a-time.h b/arch/s390/include/asm/word-at-a-time.h
new file mode 100644
index 000000000000..09b37541a175
--- /dev/null
+++ b/arch/s390/include/asm/word-at-a-time.h
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_WORD_AT_A_TIME_H
+#define _ASM_WORD_AT_A_TIME_H
+
+#include <linux/kernel.h>
+#include <asm/bitsperlong.h>
+
+struct word_at_a_time {
+ const unsigned long bits;
+};
+
+#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x7f) }
+
+static inline unsigned long prep_zero_mask(unsigned long val, unsigned long data, const struct word_at_a_time *c)
+{
+ return data;
+}
+
+static inline unsigned long create_zero_mask(unsigned long data)
+{
+ return __fls(data);
+}
+
+static inline unsigned long find_zero(unsigned long data)
+{
+ return (data ^ (BITS_PER_LONG - 1)) >> 3;
+}
+
+static inline unsigned long has_zero(unsigned long val, unsigned long *data, const struct word_at_a_time *c)
+{
+ unsigned long mask = (val & c->bits) + c->bits;
+
+ *data = ~(mask | val | c->bits);
+ return *data;
+}
+
+static inline unsigned long zero_bytemask(unsigned long data)
+{
+ return ~1UL << data;
+}
+
+#endif /* _ASM_WORD_AT_A_TIME_H */