Constant Devices

Constant devices. More...

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Detailed Description

Constant devices.

This module provides the constant devices which provide user space with its primary means of allocating memory and obtaining constant data.

The constant devices are exposed under the /dev/const/ directory:

• /dev/const/one: A readable and mappable file that returns bytes with all bits set to 1.
• /dev/const/zero: A readable and mappable file that returns bytes with all bits set to 0.
• /dev/const/null: A readable and writable file that discards all written data and returns EOF on read.

Functions
static uint64_t	const_one_read (file_t *file, void *buffer, size_t count, size_t *offset)
static void *	const_one_mmap (file_t *file, void *addr, size_t length, size_t *offset, pml_flags_t flags)
static uint64_t	const_zero_read (file_t *file, void *buffer, size_t count, size_t *offset)
static void *	const_zero_mmap (file_t *file, void *addr, size_t length, size_t *offset, pml_flags_t flags)
static uint64_t	const_null_read (file_t *file, void *buffer, size_t count, size_t *offset)
static uint64_t	const_null_write (file_t *file, const void *buffer, size_t count, size_t *offset)
static uint64_t	const_init (void)
static void	const_deinit (void)

Variables
static dentry_t *	constDir
static dentry_t *	oneFile
static dentry_t *	zeroFile
static dentry_t *	nullFile
static file_ops_t	oneOps
static file_ops_t	zeroOps
static file_ops_t	nullOps

Function Documentation

const_one_read()

static uint64_t const_one_read ( file_t *  file, void *  buffer, size_t  count, size_t *  offset  )

static

Definition at line 34 of file const.c.

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const_one_mmap()

static void * const_one_mmap ( file_t *  file, void *  addr, size_t  length, size_t *  offset, pml_flags_t  flags  )

static

Definition at line 43 of file const.c.

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const_zero_read()

static uint64_t const_zero_read ( file_t *  file, void *  buffer, size_t  count, size_t *  offset  )

static

Definition at line 63 of file const.c.

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const_zero_mmap()

static void * const_zero_mmap ( file_t *  file, void *  addr, size_t  length, size_t *  offset, pml_flags_t  flags  )

static

Definition at line 72 of file const.c.

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const_null_read()

static uint64_t const_null_read ( file_t *  file, void *  buffer, size_t  count, size_t *  offset  )

static

Definition at line 92 of file const.c.

const_null_write()

static uint64_t const_null_write ( file_t *  file, const void *  buffer, size_t  count, size_t *  offset  )

static

Definition at line 101 of file const.c.

const_init()

static uint64_t const_init ( void  )

static

Definition at line 115 of file const.c.

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const_deinit()

static void const_deinit ( void  )

static

Definition at line 154 of file const.c.

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Variable Documentation

constDir

dentry_t* constDir

static

Definition at line 29 of file const.c.

oneFile

dentry_t* oneFile

static

Definition at line 30 of file const.c.

zeroFile

dentry_t* zeroFile

static

Definition at line 31 of file const.c.

nullFile

dentry_t* nullFile

static

Definition at line 32 of file const.c.

oneOps

file_ops_t oneOps

static

Initial value:

= {
    .read = const_one_read,
    .mmap = const_one_mmap,
}

Definition at line 58 of file const.c.

zeroOps

file_ops_t zeroOps

static

Initial value:

= {
    .read = const_zero_read,
    .mmap = const_zero_mmap,
}

Definition at line 87 of file const.c.

nullOps

file_ops_t nullOps

static

Initial value:

= {
    .read = const_null_read,
    .write = const_null_write,
}

Definition at line 110 of file const.c.