/**
 * __bitmap_parse - convert an ASCII hex string into a bitmap.
 * @buf: pointer to buffer containing string.
 * @buflen: buffer size in bytes.  If string is smaller than this
 *    then it must be terminated with a \0.
 * @is_user: location of buffer, 0 indicates kernel space
 * @maskp: pointer to bitmap array that will contain result.
 * @nmaskbits: size of bitmap, in bits.
 *
 * Commas group hex digits into chunks.  Each chunk defines exactly 32
 * bits of the resultant bitmask.  No chunk may specify a value larger
 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
 * then leading 0-bits are prepended.  %-EINVAL is returned for illegal
 * characters and for grouping errors such as "1,,5", ",44", "," and "".
 * Leading and trailing whitespace accepted, but not embedded whitespace.
 */
int __bitmap_parse(const char *buf, unsigned int buflen,
                int is_user, unsigned long *maskp,
                int nmaskbits)
{
        int c, old_c, totaldigits, ndigits, nchunks, nbits;
        u32 chunk;
        const char __user __force *ubuf = (const char __user __force *)buf;

        bitmap_zero(maskp, nmaskbits);

        nchunks = nbits = totaldigits = c = 0;
        do {
                chunk = 0;
                ndigits = totaldigits;

                /* Get the next chunk of the bitmap */
                while (buflen) {
                        old_c = c;
                        if (is_user) {
                                if (__get_user(c, ubuf++))
                                        return -EFAULT;
                        }
                        else
                                c = *buf++;
                        buflen--;
                        if (isspace(c))
                                continue;

                        /*
                         * If the last character was a space and the current
                         * character isn't '\0', we've got embedded whitespace.
                         * This is a no-no, so throw an error.
                         */
                        if (totaldigits && c && isspace(old_c))
                                return -EINVAL;

                        /* A '\0' or a ',' signal the end of the chunk */
                        if (c == '\0' || c == ',')
                                break;

                        if (!isxdigit(c))
                                return -EINVAL;

                        /*
                         * Make sure there are at least 4 free bits in 'chunk'.
                         * If not, this hexdigit will overflow 'chunk', so
                         * throw an error.
                         */
                        if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
                                return -EOVERFLOW;

                        chunk = (chunk << 4) | hex_to_bin(c);
                        totaldigits++;
                }

                if (ndigits == totaldigits)
                        return -EINVAL;
                if (nchunks == 0 && chunk == 0)
                        continue;

                __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
                *maskp |= chunk;
                nchunks++;
                nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
                if (nbits > nmaskbits)
                        return -EOVERFLOW;
        } while (buflen && c == ',');

        return 0;
}

/*
 * Bitmap.
 *
 * (C) 2019.06.10 <buddy.zhang@aliyun.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/init.h>

/* header of bitmap */
#include <linux/bitmap.h>

static __init int bitmap_demo_init(void)
{
	const char *buf = "a2100347,98adef22";
	unsigned long bitmap[10];

	__bitmap_parse(buf, 32, 0, bitmap, 32 * 4);
	printk("%s bitmap: %#lx\n", buf, bitmap[0]);
	printk("%s bitmap: %#lx\n", buf, bitmap[1]);

	return 0;
}
device_initcall(bitmap_demo_init);

diff --git a/drivers/BiscuitOS/Kconfig b/drivers/BiscuitOS/Kconfig
index 4edc5a5..1a9abee 100644
--- a/drivers/BiscuitOS/Kconfig
+++ b/drivers/BiscuitOS/Kconfig
@@ -6,4 +6,14 @@ if BISCUITOS_DRV
config BISCUITOS_MISC
        bool "BiscuitOS misc driver"
+config BISCUITOS_BITMAP
+       bool "bitmap"
+
+if BISCUITOS_BITMAP
+
+config DEBUG_BISCUITOS_BITMAP
+       bool "__bitmap_parse"
+
+endif # BISCUITOS_BITMAP
+
endif # BISCUITOS_DRV

diff --git a/drivers/BiscuitOS/Makefile b/drivers/BiscuitOS/Makefile
index 82004c9..9909149 100644
--- a/drivers/BiscuitOS/Makefile
+++ b/drivers/BiscuitOS/Makefile
@@ -1 +1,2 @@
obj-$(CONFIG_BISCUITOS_MISC)     += BiscuitOS_drv.o
+obj-$(CONFIG_BISCUITOS_BITMAP)     += bitmap.o
--

Device Driver--->
    [*]BiscuitOS Driver--->
        [*]bitmap
            [*]__bitmap_parse()

usbcore: registered new interface driver usbhid
usbhid: USB HID core driver
a2100347,98adef22 bitmap: 0x98adef22
a2100347,98adef22 bitmap: 0xa2100347
aaci-pl041 10004000.aaci: ARM AC'97 Interface PL041 rev0 at 0x10004000, irq 24
aaci-pl041 10004000.aaci: FIFO 512 entries
oprofile: using arm/armv7-ca9