DH_PointAdd,
DH_PointDivide,
DH_PointMultiply
DH_PointAdd,
DH_PointDivide,
DH_PointMultiply — modify a point in place, with one message.
Syntax
#include <cogent.h>
ST_STATUS DH_PointAdd( | IP_Task* | myself, |
| | PT_pCPOINT | ppoint, |
| | double | value, |
| | IP_Msg* | hmsg, |
| | ER_hLIST | elist); |
ST_STATUS DH_PointDivide( | IP_Task* | myself, |
| | PT_pCPOINT | ppoint, |
| | double | value, |
| | IP_Msg* | hmsg, |
| | ER_hLIST | elist); |
ST_STATUS DH_PointMultiply( | IP_Task* | myself, |
| | PT_pCPOINT | ppoint, |
| | double | value, |
| | IP_Msg* | hmsg, |
| | ER_hLIST | elist); |
Arguments
- myself
- The
task handle associated with this task. This should always be
the return value from IP_NserveInit.
- ppoint
- A
pointer to a Cascade DataHub point structure. All fields are valid,
and will be treated by the write, but in the first call on a
point the address field must be zero. It will be filled in
automatically. This address will be valid so long as the point
exists in the DataHub, and if, in subsequent
DH_* functions, the address is provided
for this point, the function will run slightly faster.
- value
- The
value to be used to modify the value of the
point.
- hmsg
- A
handle to a previously allocated message structure (using IP_MsgCreate) providing enough
buffer space to handle the inter-process communication
associated with the DataHub transaction.
- elist
- A
return value containing error information. This is unimplemented in this
version, and should be NULL.
Returns
ST_OK on
success, ST_ERROR on failure, or some other
value of ST_STATUS.
Description
These functions give an atomic
way to modify a value in the DataHub in place, using a single
message. Normally a value is modified in three steps: read,
modify, and write. This functions offers a way to modify a value
without interference or serialization problems.
The operations provided are as follows:
