From a148996a7f9097a1f8e43cc62bd65972b008cad4 Mon Sep 17 00:00:00 2001
From: Anup Patel <anup.patel@wdc.com>
Date: Wed, 4 Mar 2020 11:48:31 +0530
Subject: include: sbi_bitops: More useful bit operations
This patch extends our bit operation library with mechanism to:
1. Iteratively traverse bits
2. Set bit
3. Clear bit
4. Change bit
5. ... other helpful functions ...
Most the above is adopted from Xvisor sources.
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
---
include/sbi/sbi_bitops.h | 141 ++++++++++++++++++++++++++++++++-
lib/sbi/objects.mk | 1 +
lib/sbi/sbi_bitops.c | 200 +++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 340 insertions(+), 2 deletions(-)
create mode 100644 lib/sbi/sbi_bitops.c
diff --git a/include/sbi/sbi_bitops.h b/include/sbi/sbi_bitops.h
index 10c29f1..c55ced0 100644
--- a/include/sbi/sbi_bitops.h
+++ b/include/sbi/sbi_bitops.h
@@ -4,7 +4,7 @@
* Copyright (c) 2019 Western Digital Corporation or its affiliates.
*
* Authors:
- * Atish Patra<atish.patra@wdc.com>
+ * Atish Patra <atish.patra@wdc.com>
*/
#ifndef __SBI_BITOPS_H__
@@ -25,8 +25,16 @@
#define INSERT_FIELD(val, which, fieldval) \
(((val) & ~(which)) | ((fieldval) * ((which) & ~((which)-1))))
+#define BITS_TO_LONGS(nbits) (((nbits) + BITS_PER_LONG - 1) / \
+ BITS_PER_LONG)
+
+#define BIT(nr) (1UL << (nr))
#define BIT_MASK(nr) (1UL << ((nr) % BITS_PER_LONG))
-#define BIT_WORD(nr) ((nr) / BITS_PER_LONG)
+#define BIT_WORD(bit) ((bit) / BITS_PER_LONG)
+#define BIT_WORD_OFFSET(bit) ((bit) & (BITS_PER_LONG - 1))
+
+#define GENMASK(h, l) \
+ (((~0UL) - (1UL << (l)) + 1) & (~0UL >> (BITS_PER_LONG - 1 - (h))))
/**
* ffs - Find first bit set
@@ -184,4 +192,133 @@ static inline unsigned long __fls(unsigned long word)
return num;
}
+#define for_each_set_bit(bit, addr, size) \
+ for ((bit) = find_first_bit((addr), (size)); \
+ (bit) < (size); \
+ (bit) = find_next_bit((addr), (size), (bit) + 1))
+
+/* same as for_each_set_bit() but use bit as value to start with */
+#define for_each_set_bit_from(bit, addr, size) \
+ for ((bit) = find_next_bit((addr), (size), (bit)); \
+ (bit) < (size); \
+ (bit) = find_next_bit((addr), (size), (bit) + 1))
+
+#define for_each_clear_bit(bit, addr, size) \
+ for ((bit) = find_first_zero_bit((addr), (size)); \
+ (bit) < (size); \
+ (bit) = find_next_zero_bit((addr), (size), (bit) + 1))
+
+/* same as for_each_clear_bit() but use bit as value to start with */
+#define for_each_clear_bit_from(bit, addr, size) \
+ for ((bit) = find_next_zero_bit((addr), (size), (bit)); \
+ (bit) < (size); \
+ (bit) = find_next_zero_bit((addr), (size), (bit) + 1))
+
+unsigned long find_first_bit(const unsigned long *addr,
+ unsigned long size);
+
+unsigned long find_first_zero_bit(const unsigned long *addr,
+ unsigned long size);
+
+unsigned long find_last_bit(const unsigned long *addr,
+ unsigned long size);
+
+unsigned long find_next_bit(const unsigned long *addr,
+ unsigned long size, unsigned long offset);
+
+unsigned long find_next_zero_bit(const unsigned long *addr,
+ unsigned long size,
+ unsigned long offset);
+
+/**
+ * __set_bit - Set a bit in memory
+ * @nr: the bit to set
+ * @addr: the address to start counting from
+ *
+ * This function is non-atomic and may be reordered.
+ */
+static inline void __set_bit(int nr, volatile unsigned long *addr)
+{
+ unsigned long mask = BIT_MASK(nr);
+ unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+
+ *p |= mask;
+}
+
+/**
+ * __clear_bit - Clear a bit in memory
+ * @nr: the bit to clear
+ * @addr: the address to start counting from
+ *
+ * This function is non-atomic and may be reordered.
+ */
+static inline void __clear_bit(int nr, volatile unsigned long *addr)
+{
+ unsigned long mask = BIT_MASK(nr);
+ unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+
+ *p &= ~mask;
+}
+
+/**
+ * __change_bit - Toggle a bit in memory
+ * @nr: the bit to change
+ * @addr: the address to start counting from
+ *
+ * This function is non-atomic and may be reordered.
+ */
+static inline void __change_bit(int nr, volatile unsigned long *addr)
+{
+ unsigned long mask = BIT_MASK(nr);
+ unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+
+ *p ^= mask;
+}
+
+/**
+ * __test_and_set_bit - Set a bit and return its old value
+ * @nr: Bit to set
+ * @addr: Address to count from
+ *
+ * This operation is non-atomic and can be reordered.
+ */
+static inline int __test_and_set_bit(int nr, volatile unsigned long *addr)
+{
+ unsigned long mask = BIT_MASK(nr);
+ unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+ unsigned long old = *p;
+
+ *p = old | mask;
+ return (old & mask) != 0;
+}
+
+/**
+ * __test_and_clear_bit - Clear a bit and return its old value
+ * @nr: Bit to clear
+ * @addr: Address to count from
+ *
+ * This operation is non-atomic and can be reordered.
+ */
+static inline int __test_and_clear_bit(int nr, volatile unsigned long *addr)
+{
+ unsigned long mask = BIT_MASK(nr);
+ unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+ unsigned long old = *p;
+
+ *p = old & ~mask;
+ return (old & mask) != 0;
+}
+
+/**
+ * __test_bit - Determine whether a bit is set
+ * @nr: bit number to test
+ * @addr: Address to start counting from
+ *
+ * This operation is non-atomic and can be reordered.
+ */
+static inline int __test_bit(int nr, const volatile unsigned long *addr)
+{
+ return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
+}
+
#endif
diff --git a/lib/sbi/objects.mk b/lib/sbi/objects.mk
index 39e9295..5c30d97 100644
--- a/lib/sbi/objects.mk
+++ b/lib/sbi/objects.mk
@@ -12,6 +12,7 @@ libsbi-objs-y += riscv_atomic.o
libsbi-objs-y += riscv_hardfp.o
libsbi-objs-y += riscv_locks.o
+libsbi-objs-y += sbi_bitops.o
libsbi-objs-y += sbi_console.o
libsbi-objs-y += sbi_ecall.o
libsbi-objs-y += sbi_ecall_base.o
diff --git a/lib/sbi/sbi_bitops.c b/lib/sbi/sbi_bitops.c
new file mode 100644
index 0000000..1355243
--- /dev/null
+++ b/lib/sbi/sbi_bitops.c
@@ -0,0 +1,200 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2020 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ * Atish Patra <atish.patra@wdc.com>
+ * Anup Patel <anup.patel@wdc.com>
+ */
+
+#include <sbi/sbi_bitops.h>
+
+#define BITOP_WORD(nr) ((nr) / BITS_PER_LONG)
+
+/**
+ * find_first_bit - find the first set bit in a memory region
+ * @addr: The address to start the search at
+ * @size: The maximum size to search
+ *
+ * Returns the bit number of the first set bit.
+ */
+unsigned long find_first_bit(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 == 0UL) /* Are any bits set? */
+ return result + size; /* Nope. */
+found:
+ return result + __ffs(tmp);
+}
+
+/**
+ * find_first_zero_bit - find the first cleared bit in a memory region
+ * @addr: The address to start the search at
+ * @size: The maximum size to search
+ *
+ * Returns the bit number of the first cleared bit.
+ */
+unsigned long find_first_zero_bit(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 << size);
+ if (tmp == ~0UL) /* Are any bits zero? */
+ return result + size; /* Nope. */
+found:
+ return result + ffz(tmp);
+}
+
+/**
+ * find_last_bit - find the last set bit in a memory region
+ * @addr: The address to start the search at
+ * @size: The maximum size to search
+ *
+ * Returns the bit number of the first set bit, or size.
+ */
+unsigned long find_last_bit(const unsigned long *addr,
+ unsigned long size)
+{
+ unsigned long words;
+ unsigned long tmp;
+
+ /* Start at final word. */
+ words = size / BITS_PER_LONG;
+
+ /* Partial final word? */
+ if (size & (BITS_PER_LONG-1)) {
+ tmp = (addr[words] & (~0UL >> (BITS_PER_LONG
+ - (size & (BITS_PER_LONG-1)))));
+ if (tmp)
+ goto found;
+ }
+
+ while (words) {
+ tmp = addr[--words];
+ if (tmp) {
+found:
+ return words * BITS_PER_LONG + __fls(tmp);
+ }
+ }
+
+ /* Not found */
+ return size;
+}
+
+/**
+ * find_next_bit - find the next set bit in a memory region
+ * @addr: The address to base the search on
+ * @offset: The bitnumber to start searching at
+ * @size: The bitmap size in bits
+ */
+unsigned long find_next_bit(const unsigned long *addr,
+ unsigned long size, unsigned long offset)
+{
+ const unsigned long *p = addr + BITOP_WORD(offset);
+ 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 == 0UL) /* Are any bits set? */
+ return result + size; /* Nope. */
+found_middle:
+ return result + __ffs(tmp);
+}
+
+/**
+ * find_next_zero_bit - find the next cleared bit in a memory region
+ * @addr: The address to base the search on
+ * @offset: The bitnumber to start searching at
+ * @size: The bitmap size in bits
+ */
+unsigned long find_next_zero_bit(const unsigned long *addr,
+ unsigned long size,
+ unsigned long offset)
+{
+ const unsigned long *p = addr + BITOP_WORD(offset);
+ 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 >> (BITS_PER_LONG - 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 << size;
+ if (tmp == ~0UL) /* Are any bits zero? */
+ return result + size; /* Nope. */
+found_middle:
+ return result + ffz(tmp);
+}
--
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