diff --git a/doc/command_funcref.txt b/doc/command_funcref.txt index 167fe0a..08b152b 100644 --- a/doc/command_funcref.txt +++ b/doc/command_funcref.txt @@ -4,43 +4,47 @@ Retval: int Param: comedi_t * device Param: unsigned int subdevice Description: - The function comedi_cancel() can be used to stop a command + The function comedi_cancel can be used to stop a command previously started by - comedi_command + comedi_command which is still in progress - on the subdevice indicated by the parameters device - and subdevice. + on the subdevice indicated by the parameters device + and subdevice. Returns: - If successful, 0 is returned, otherwise -1. + If successful, 0 is returned, otherwise + -1. Function: comedi_command -- start streaming input/output Retval: int Param: comedi_t * device Param: comedi_cmd * command Description: - The function comedi_command() starts a streaming input + The function comedi_command starts a streaming input or output. The - command structure *command specifies + command structure pointed to by command specifies settings for the acquisition. The command must be able to pass - comedi_command_test - with a return value of 0, or comedi_command() will fail. + comedi_command_test + with a return value of 0, or + comedi_command will fail. For input subdevices, sample values are read using the - function read() on the device file. For output subdevices, sample values are written - using the function write(). + function read on the device file. For output subdevices, + sample values are written using the function write. Returns: - If successful, 0 is returned, otherwise -1. + If successful, 0 is returned, otherwise + -1. Function: comedi_command_test -- test streaming input/output configuration Retval: int Param: comedi_t * device Param: comedi_cmd * command Description: - The function comedi_command_test() tests the command structure pointed - to by the parameter command and returns an + The function comedi_command_test tests the command structure pointed + to by the parameter command and returns an integer describing the testing stages that were successfully passed. In addition, if elements - of the *command structure are invalid, they may be modified. Source + of the comedi_cmd structure are invalid, they may be modified. Source elements are modified to remove invalid source triggers. Argument elements are adjusted or rounded to the nearest valid value. @@ -48,11 +52,12 @@ Description: - 0 indicates a valid command. + 0 indicates a valid command. - 1 indicates that one of the *_src + 1 indicates that one of the + …_src members of the command contained an unsupported trigger. The bits corresponding to the unsupported triggers are zeroed. @@ -60,33 +65,37 @@ Description: - 2 indicates that the particular combination - of *_src settings is not supported by the driver, or that - one of the *_src members has the bit corresponding to + 2 indicates that the particular combination + of …_src settings is not supported by the driver, or that + one of the …_src members has the bit corresponding to multiple trigger sources set at the same time. - 3 indicates that one of the *_arg members + 3 indicates that one of the + …_arg members of the command is set outside the range of allowable values. - For instance, an argument for a TRIG_TIMER source which - exceeds the board's maximum speed. The invalid *_arg + For instance, an argument for a + TRIG_TIMER source which + exceeds the board's maximum speed. The invalid + …_arg members will be adjusted to valid values. - 4 indicates that one of the *_arg members + 4 indicates that one of the + …_arg members required adjustment. For instance, the argument of a - TRIG_TIMER source may have been rounded to the nearest + TRIG_TIMER source may have been rounded to the nearest timing period supported by the board. - 5 indicates that some aspect of the - command's chanlist is unsupported by the board. For example, + 5 indicates that some aspect of the + command's chanlist is unsupported by the board. For example, some analog input boards require that all channels in the chanlist use the same input range. @@ -98,31 +107,32 @@ Retval: int Param: comedi_t * device Param: unsigned int subdevice Description: - The function comedi_get_buffer_contents() is used on a subdevice + The function comedi_get_buffer_contents is used on a subdevice that has a Comedi command in progress. The number of bytes that are available in the streaming buffer is returned. If there is - an error, -1 is returned. + an error, -1 is returned. Function: comedi_get_buffer_offset -- streaming buffer status Retval: int Param: comedi_t * device Param: unsigned int subdevice Description: - The function comedi_get_buffer_offset() is used on a subdevice + The function comedi_get_buffer_offset is used on a subdevice that has a Comedi command in progress. This function returns the offset in bytes of the read pointer in the streaming buffer. This offset is only useful for memory mapped buffers. - If there is an error, -1 is returned. + If there is an error, -1 is returned. Function: comedi_get_buffer_size -- streaming buffer size of subdevice Retval: int Param: comedi_t * device Param: unsigned int subdevice Description: - The function comedi_get_buffer_size() returns the size (in bytes) + The function comedi_get_buffer_size returns the size (in bytes) of the streaming buffer for the subdevice specified by - device and - subdevice. On error, -1 is returned. + device and + subdevice. + On error, -1 is returned. Function: comedi_get_cmd_generic_timed -- streaming input/output capabilities Retval: int @@ -133,21 +143,26 @@ Param: unsigned int chanlist_len Param: unsigned int scan_period_ns Description: The command capabilities of the subdevice indicated by the parameters - device and subdevice + device and subdevice are probed, and the results placed in the - command structure pointed to by the parameter command. The command - structure *command is modified to be a + command structure pointed to by the parameter command. + The command structure pointed to by command + is modified to be a valid command that can be used as a parameter to - comedi_command - (after the command has additionally been assigned a valid chanlist array). - The command measures scans consisting of chanlist_len + comedi_command + (after the command has additionally been assigned a valid + chanlist array). + The command measures scans consisting of chanlist_len channels at a scan rate that corresponds to a period of - scan_period_ns nanoseconds. + scan_period_ns nanoseconds. The rate is adjusted to a rate that the device can handle. Returns: - If successful, 0 is returned, otherwise -1. + If successful, 0 is returned, otherwise + -1. Function: comedi_get_cmd_src_mask -- streaming input/output capabilities Retval: int @@ -156,46 +171,52 @@ Param: unsigned int subdevice Param: comedi_cmd * command Description: The command capabilities of the subdevice indicated by the parameters - device and subdevice + device and subdevice are probed, and the results placed in the - command structure *command. The trigger + command structure pointed to by command. The trigger source elements of the command structure are set to be the bitwise-or of the subdevice's supported trigger sources. Other elements in the structure are undefined. Returns: - If successful, 0 is returned, otherwise -1. + If successful, 0 is returned, otherwise + -1. Function: comedi_get_max_buffer_size -- maximum streaming buffer size Retval: int Param: comedi_t * device Param: unsigned int subdevice Description: - The function comedi_get_max_buffer_size() returns the maximum + The function comedi_get_max_buffer_size returns the maximum allowable size (in bytes) of the streaming buffer for the subdevice - specified by device and subdevice. + specified by device + and subdevice. Changing the maximum buffer size can be accomplished with - comedi_set_max_buffer_size - or with the comedi_config program, - and requires appropriate privileges. On error, -1 is returned. + comedi_set_max_buffer_size + or with the comedi_config program, + and requires appropriate privileges. On error, -1 is returned. Function: comedi_get_read_subdevice -- find streaming input subdevice Retval: int Param: comedi_t * device Description: - The function comedi_get_read_subdevice() returns the subdevice + The function comedi_get_read_subdevice returns the + index of the subdevice whose streaming input buffer is accessible through the - device dev. If - there is no such subdevice, -1 is returned. + device device. If + there is no such subdevice, -1 is returned. Function: comedi_get_write_subdevice -- find streaming output subdevice Retval: int Param: comedi_t * device Description: - The function comedi_get_write_subdevice() returns the subdevice + The function comedi_get_write_subdevice returns the + index of the subdevice whose streaming output buffer is accessible through the - device dev. If there is no such subdevice, - -1 is returned. + device device. If there is no such subdevice, + -1 is returned. Function: comedi_mark_buffer_read -- streaming buffer control Retval: int @@ -203,24 +224,25 @@ Param: comedi_t * device Param: unsigned int subdevice Param: unsigned int num_bytes Description: - The function comedi_mark_buffer_read() is used on a subdevice + The function comedi_mark_buffer_read is used on a subdevice that has a Comedi input command in progress. It should only be used - if you are using a mmap() to read data from Comedi's buffer - (as opposed to calling read() on the device file), + if you are using a mmap mapping to read data from Comedi's buffer + (as opposed to calling read on the device file), since Comedi will automatically keep track of how many bytes have been - transferred via read() calls. This function is - used to indicate that the next num_bytes + transferred via read calls. This function is + used to indicate that the next num_bytes bytes in the buffer are no longer needed and may be discarded. Returns: The function comedi_mark_buffer_read returns the number of bytes successfully marked as read, - or -1 on error. The return value may be less than - num_bytes if you attempt to mark more + or -1 on error. The return value may be less than + num_bytes if you attempt to mark more bytes read than are currently available for reading, or - if num_bytes must be rounded down + if num_bytes must be rounded down to be an exact multiple of the subdevice's - sample size (either sizeof(sampl_t) or sizeof(lsampl_t)). + sample size (either sizeof(sampl_t) or + sizeof(lsampl_t)). Function: comedi_mark_buffer_written -- streaming buffer control Retval: int @@ -228,38 +250,39 @@ Param: comedi_t * device Param: unsigned int subdevice Param: unsigned int num_bytes Description: - The function comedi_mark_buffer_written() is used on a subdevice + The function comedi_mark_buffer_written is used on a subdevice that has a Comedi output command in progress. It should only be used - if you are using a mmap() to write data to Comedi's buffer - (as opposed to calling write() on the device + if you are using a mmap mapping to write data to Comedi's buffer + (as opposed to calling write on the device file), since Comedi will automatically keep track of how many bytes have been - transferred via write() calls. This function is - used to indicate that the next num_bytes + transferred via write calls. This function is + used to indicate that the next num_bytes bytes in the buffer are valid and may be sent to the device. Returns: The function comedi_mark_buffer_written returns number of bytes successfully marked as written, - or -1 on error. The return value may be less than - num_bytes if you attempt to mark more + or -1 on error. The return value may be less than + num_bytes if you attempt to mark more bytes written than the amount of free space currently available in the output buffer, or - if num_bytes must be + if num_bytes must be rounded down to be an exact multiple of the subdevice's - sample size (either sizeof(sampl_t) or sizeof(lsampl_t)). + sample size (either sizeof(sampl_t) + or sizeof(lsampl_t)). Function: comedi_poll -- force updating of streaming buffer Retval: int Param: comedi_t * device Param: unsigned int subdevice Description: - The function comedi_poll() is used on a subdevice that has a + The function comedi_poll is used on a subdevice that has a Comedi command in progress in order to update the streaming buffer. If supported by the driver, all available samples are copied to the streaming buffer. These samples may be pending in DMA buffers or device FIFOs. If successful, the number of additional bytes - available is returned. If there is an error, -1 is returned. + available is returned. If there is an error, -1 is returned. Function: comedi_set_buffer_size -- streaming buffer size of subdevice Retval: int @@ -267,32 +290,35 @@ Param: comedi_t * device Param: unsigned int subdevice Param: unsigned int size Description: - The function comedi_set_buffer_size() changes the size of the + The function comedi_set_buffer_size changes the size of the streaming buffer for the subdevice specified by - device and subdevice. - The buffer size will be set to size bytes, + device and subdevice. + The buffer size will be set to size bytes, rounded up to a multiple of the virtual memory page size. The virtual memory page size can be determined using - sysconf(_SC_PAGE_SIZE). + sysconf(_SC_PAGE_SIZE). This function does not require special privileges. However, it is limited to a (adjustable) maximum buffer size, which can - be changed by a priveliged user calling - comedi_set_max_buffer_size, - or running the program comedi_config. + be changed by a privileged user calling + comedi_set_max_buffer_size, + or running the program comedi_config. Returns: The new buffer size in bytes is returned on success. On error, - -1 is returned. + -1 is returned. -Function: comedi_set_max_buffer_size -- streaming buffer size of subdevice +Function: comedi_set_max_buffer_size -- streaming maximum buffer size of subdevice Retval: int Param: comedi_t * device Param: unsigned int subdevice Param: unsigned int max_size Description: - The function comedi_set_max_buffer_size() changes the maximum + The function comedi_set_max_buffer_size changes the maximum allowable size (in bytes) of the streaming buffer for the subdevice - specified by device and subdevice. Changing the maximum buffer + specified by device and + subdevice. Changing the maximum buffer size requires the user to have appropriate privileges. Returns: - The old buffer size is returned on success. On error, -1 is returned. + The new maximum buffer size is returned on success. On error, -1 is returned.