USB_PARSE_DATA(9F) Kernel Functions for Drivers USB_PARSE_DATA(9F)


NAME


usb_parse_data - Tokenize and align the bytes of raw variable-format data

SYNOPSIS


#include <sys/usb/usba.h>


size_t usb_parse_data(char *format, const uchar_t *data,
size_t datalen, void *structure, size_t structlen);


INTERFACE LEVEL


Solaris DDI specific (Solaris DDI)

PARAMETERS


format
Null terminated string describing the format of the data
structure for general-purpose byte swapping. The letters
"c," "s," "l," and "L" represent 1, 2, 4 and 8 byte
quantities, respectively. A descriptor that consists of a
short and two bytes would be described by "scc." A number
preceding a letter serves as a multiplier of that letter. A
format equivalent to "scc" is "s2c."


data
Raw descriptor data to parse.


datalen
Length, in bytes, of the raw descriptor data buffer.


structure
Destination data buffer where parsed data is returned.


structlen
Length, in bytes, of the destination data buffer. Parsed
result length will not exceed this value.


DESCRIPTION


The usb_parse_data function parses data such as a variable-format class-
or vendor-specific descriptor. The function also tokenizes and aligns the
bytes of raw descriptor data into fields of a variable-format descriptor.


While the USBA framework can parse the endpoint, interface,
configuration, and string descriptors defined by the USB 3.0
specification, the format of class- or vendor-specific descriptors cannot
be explicitly defined by the specification and will be unique for each.
The format argument defines how to parse such a descriptor.


While the USB specification defines bit ordering as little-endian, this
routine (like the entire API), converts the data to the endianness of the
host.


The structlen parameter defines the size of the destination data buffer.
Data is truncated to this size if the destination data buffer is too
small.

RETURN VALUES


On success: Returns the size (in bytes) of the parsed data result.


On failure: Returns 0. (Same as USB_PARSE_ERROR).

CONTEXT


May be called from user, kernel or interrupt context.

EXAMPLES


/*
* Parse raw descriptor data in buf, putting result into ret_descr.
* ret_buf_len holds the size of ret_descr buf; routine returns
* number of resulting bytes.
*
* Descriptor being parsed has 2 chars, followed by one short,
* 3 chars and one more short.
*/
size_t size_of_returned_descr;
xxx_descr_t ret_descr;

size_of_returned_descr = usb_parse_data("ccscccs",
buf, sizeof(buf), (void *)ret_descr, (sizeof)xxx_descr_t));
if (size_of_returned_descr < (sizeof (xxx_descr_t))) {
/* Data truncated. */
}

or:

size_of_returned_descr = usb_parse_data("2cs3cs",
buf, sizeof(buf), (void *)ret_descr, (sizeof)xxx_descr_t));
if (size_of_returned_descr < (sizeof (xxx_descr_t))) {
/* Data truncated. */
}


ATTRIBUTES


See attributes(5) for descriptions of the following attributes:


+--------------------+-------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-------------------+
|Architecture | PCI-based systems |
+--------------------+-------------------+
|Interface stability | Committed |
+--------------------+-------------------+

SEE ALSO


attributes(5), usb_get_dev_data(9F), usb_get_string_descr(9F),
usb_get_cfg(9F)


April 4, 2019 USB_PARSE_DATA(9F)