lib: Add support for generic packing operations

[linux-2.6-microblaze.git] / include / linux / packing.h

diff --git a/include/linux/packing.h b/include/linux/packing.h
new file mode 100644 (file)
index 0000000..5466773
--- /dev/null
+++ b/include/linux/packing.h
@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright (c) 2016-2018, NXP Semiconductors
+ * Copyright (c) 2018-2019, Vladimir Oltean <olteanv@gmail.com>
+ */
+#ifndef _LINUX_PACKING_H
+#define _LINUX_PACKING_H
+
+#include <linux/types.h>
+#include <linux/bitops.h>
+
+#define QUIRK_MSB_ON_THE_RIGHT BIT(0)
+#define QUIRK_LITTLE_ENDIAN    BIT(1)
+#define QUIRK_LSW32_IS_FIRST   BIT(2)
+
+enum packing_op {
+       PACK,
+       UNPACK,
+};
+
+/**
+ * packing - Convert numbers (currently u64) between a packed and an unpacked
+ *          format. Unpacked means laid out in memory in the CPU's native
+ *          understanding of integers, while packed means anything else that
+ *          requires translation.
+ *
+ * @pbuf: Pointer to a buffer holding the packed value.
+ * @uval: Pointer to an u64 holding the unpacked value.
+ * @startbit: The index (in logical notation, compensated for quirks) where
+ *           the packed value starts within pbuf. Must be larger than, or
+ *           equal to, endbit.
+ * @endbit: The index (in logical notation, compensated for quirks) where
+ *         the packed value ends within pbuf. Must be smaller than, or equal
+ *         to, startbit.
+ * @op: If PACK, then uval will be treated as const pointer and copied (packed)
+ *     into pbuf, between startbit and endbit.
+ *     If UNPACK, then pbuf will be treated as const pointer and the logical
+ *     value between startbit and endbit will be copied (unpacked) to uval.
+ * @quirks: A bit mask of QUIRK_LITTLE_ENDIAN, QUIRK_LSW32_IS_FIRST and
+ *         QUIRK_MSB_ON_THE_RIGHT.
+ *
+ * Return: 0 on success, EINVAL or ERANGE if called incorrectly. Assuming
+ *        correct usage, return code may be discarded.
+ *        If op is PACK, pbuf is modified.
+ *        If op is UNPACK, uval is modified.
+ */
+int packing(void *pbuf, u64 *uval, int startbit, int endbit, size_t pbuflen,
+           enum packing_op op, u8 quirks);
+
+#endif