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CAM_CDBPARSE (3) | C library functions | Unix Manual Pages | :man▋
These functions may be used in new applications, but users may find it easier to use the various SCSI CCB building functions included with the cam(3) library. (e.g. cam_fill_csio, scsi_start_stop, and scsi_read_write) csio_build builds up a ccb_scsiio structure based on the information provided in the variable argument list. It gracefully handles a NULL data_ptr argument passed to it. dxfer_len is the length of the data phase; the data transfer direction is determined by the flags argument. data_ptr is the data buffer used during the SCSI data phase. If no data is to be transferred for the SCSI command in question, this should be set to NULL. If there is data to transfer for the command, this buffer must be at least dxfer_len long. flags are the flags defined in Multiple flags should be ORed together. Any of the CCB flags may be used, although it is worth noting several important ones here:
The retry_count tells the kernel how many times to retry the command in question. The retry count is ignored unless the pass(4) driver is told to enable error recovery via the CAM_PASS_ERR_RECOVER flag. The timeout tells the kernel how long to wait for the given command to complete. If the timeout expires and the command has not completed, the CCB will be returned from the kernel with an appropriate error status. cmd_spec is a CDB format specifier used to build up the SCSI CDB. This text string is made up of a list of field specifiers. Field specifiers specify the value for each CDB field (including indicating that the value be taken from the next argument in the variable argument list), the width of the field in bits or bytes, and an optional name. White space is ignored, and the pound sign (’#’) introduces a comment that ends at the end of the current line. The optional name is the first part of a field specifier and is in curly braces. The text in curly braces in this example are the names: "{PS} v:b1 {Reserved} 0:b1 {Page Code} v:b6 # Mode select page"
This field specifier has two one bit fields and one six bit field. The second one bit field is the constant value 0 and the first one bit field and the six bit field are taken from the variable argument list. Multi byte fields are swapped into the SCSI byte order in the CDB and white space is ignored. When the field is a hex value or the letter v, (e.g., "1A" or "v") then a single byte value is copied to the next unused byte of the CDB. When the letter v is used the next integer argument is taken from the variable argument list and that value used. A constant hex value followed by a field width specifier or the letter v followed by a field width specifier (e.g., 3:4, 3:b4, 3:i3, v:i3) specifies a field of a given bit or byte width. Either the constant value or (for the V specifier) the next integer value from the variable argument list is copied to the next unused bits or bytes of the CDB. A decimal number or the letter b followed by a decimal number field width indicates a bit field of that width. The bit fields are packed as tightly as possible beginning with the high bit (so that it reads the same as the SCSI spec), and a new byte of the CDB is started whenever a byte fills completely or when an i field is encountered. A field width specifier consisting of the letter i followed by either 1, 2, 3 or 4 indicates a 1, 2, 3 or 4 byte integral value that must be swapped into SCSI byte order (MSB first). For the v field specifier the next integer argument is taken from the variable argument list and that value is used swapped into SCSI byte order. csio_build_visit operates similarly to csio_build, except that the values to substitute for variable arguments in cmd_spec are retrieved via the arg_get function passed in to csio_build_visit instead of via stdarg(3). The arg_get function takes two arguments:
csio_decode is used to decode information from the data in phase of the SCSI transfer. The decoding is similar to the command specifier processing of csio_build except that the data is extracted from the data pointed to by csio->data_ptr. The stdarg list should be pointers to integers instead of integer values. A seek field type and a suppression modifier are added. The * suppression modifier (e.g., *i3 or *b4) suppresses assignment from the field and can be used to skip over bytes or bits in the data, without having to copy them to a dummy variable in the arg list. The seek field type s permits you to skip over data. This seeks to an absolute position (s3) or a relative position (s+3) in the data, based on whether or not the presence of the ’+’ sign. The seek value can be specified as v and the next integer value from the argument list will be used as the seek value. csio_decode_visit operates like csio_decode except that instead of placing the decoded contents of the buffer in variadic arguments, the decoded buffer contents are returned to the user via the arg_put function that is passed in. The arg_put function takes several arguments:
buff_decode decodes an arbitrary data buffer using the method described above for csio_decode. buff_decode_visit decodes an arbitrary data buffer using the method described above for csio_decode_visit. csio_encode encodes the data_ptr portion (not the CDB!) of a ccb_scsiio structure, using the method described above for csio_build. csio_encode_visit encodes the data_ptr portion (not the CDB!) of a ccb_scsiio structure, using the method described above for csio_build_visit. buff_encode_visit encodes an arbitrary data pointer, using the method described above for csio_build_visit.
csio_decode, csio_decode_visit, buff_decode, and buff_decode_visit return the number of assignments performed.
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