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Subject[PATCH v3 1/7] Add multibyte memset functions
Date
From: Matthew Wilcox <mawilcox@microsoft.com>

memset16(), memset32() and memset64() are like memset(), but allow the
caller to fill the destination with a multibyte pattern. memset_l()
and memset_p() allow the caller to use unsigned long and pointer
values respectively. memset64() is currently only available on 64-bit
architectures.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
---
include/linux/string.h | 30 ++++++++++++++++++++++
lib/string.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 98 insertions(+)

diff --git a/include/linux/string.h b/include/linux/string.h
index 26b6f6a66f83..b376875b650c 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -99,6 +99,36 @@ extern __kernel_size_t strcspn(const char *,const char *);
#ifndef __HAVE_ARCH_MEMSET
extern void * memset(void *,int,__kernel_size_t);
#endif
+
+#ifndef __HAVE_ARCH_MEMSET16
+extern void *memset16(uint16_t *, uint16_t, __kernel_size_t);
+#endif
+
+#ifndef __HAVE_ARCH_MEMSET32
+extern void *memset32(uint32_t *, uint32_t, __kernel_size_t);
+#endif
+
+#ifndef __HAVE_ARCH_MEMSET64
+extern void *memset64(uint64_t *, uint64_t, __kernel_size_t);
+#endif
+
+static inline void *memset_l(unsigned long *p, unsigned long v,
+ __kernel_size_t n)
+{
+ if (BITS_PER_LONG == 32)
+ return memset32((uint32_t *)p, v, n);
+ else
+ return memset64((uint64_t *)p, v, n);
+}
+
+static inline void *memset_p(void **p, void *v, __kernel_size_t n)
+{
+ if (BITS_PER_LONG == 32)
+ return memset32((uint32_t *)p, (uintptr_t)v, n);
+ else
+ return memset64((uint64_t *)p, (uintptr_t)v, n);
+}
+
#ifndef __HAVE_ARCH_MEMCPY
extern void * memcpy(void *,const void *,__kernel_size_t);
#endif
diff --git a/lib/string.c b/lib/string.c
index ed83562a53ae..f18ba402e503 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -697,6 +697,74 @@ void memzero_explicit(void *s, size_t count)
}
EXPORT_SYMBOL(memzero_explicit);

+#ifndef __HAVE_ARCH_MEMSET16
+/**
+ * memset16() - Fill a memory area with a uint16_t
+ * @s: Pointer to the start of the area.
+ * @v: The value to fill the area with
+ * @count: The number of values to store
+ *
+ * Differs from memset() in that it fills with a uint16_t instead
+ * of a byte. Remember that @count is the number of uint16_ts to
+ * store, not the number of bytes.
+ */
+void *memset16(uint16_t *s, uint16_t v, size_t count)
+{
+ uint16_t *xs = s;
+
+ while (count--)
+ *xs++ = v;
+ return s;
+}
+EXPORT_SYMBOL(memset16);
+#endif
+
+#ifndef __HAVE_ARCH_MEMSET32
+/**
+ * memset32() - Fill a memory area with a uint32_t
+ * @s: Pointer to the start of the area.
+ * @v: The value to fill the area with
+ * @count: The number of values to store
+ *
+ * Differs from memset() in that it fills with a uint32_t instead
+ * of a byte. Remember that @count is the number of uint32_ts to
+ * store, not the number of bytes.
+ */
+void *memset32(uint32_t *s, uint32_t v, size_t count)
+{
+ uint32_t *xs = s;
+
+ while (count--)
+ *xs++ = v;
+ return s;
+}
+EXPORT_SYMBOL(memset32);
+#endif
+
+#ifndef __HAVE_ARCH_MEMSET64
+#if BITS_PER_LONG > 32
+/**
+ * memset64() - Fill a memory area with a uint64_t
+ * @s: Pointer to the start of the area.
+ * @v: The value to fill the area with
+ * @count: The number of values to store
+ *
+ * Differs from memset() in that it fills with a uint64_t instead
+ * of a byte. Remember that @count is the number of uint64_ts to
+ * store, not the number of bytes.
+ */
+void *memset64(uint64_t *s, uint64_t v, size_t count)
+{
+ uint64_t *xs = s;
+
+ while (count--)
+ *xs++ = v;
+ return s;
+}
+EXPORT_SYMBOL(memset64);
+#endif
+#endif
+
#ifndef __HAVE_ARCH_MEMCPY
/**
* memcpy - Copy one area of memory to another
--
2.11.0
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