ParallelFor

Perform parallel iterations:

HmppResult HMPP_ParallelFor (int32_t numTasks, void *arg, function func);

Multiple tasks to be executed can be encapsulated in HmppResult(*function)(int32_t i, void *arg). For details, see the example.

Parameters

Parameter	Description	Value Range	Input/Output
numTasks	Number of tasks	The value is greater than 0. If the value is less than 0, no exceptions are reported and such a value indicates that no tasks are created.	Input
arg	Pointer to the parameter value of func	The value cannot be NULL.	Input
func	Pointer to the function (task) to be executed	The value cannot be NULL.	Input

Return Value

Success: HMPP_STS_NO_ERR
Failure: An error code is returned.

Error Codes

Error Code	Description
HMPP_STS_NULL_PTR_ERR	The arg or func pointer is NULL.

An error code will be returned if the multi-thread mode is enabled. You can set the error code in the user-defined function.

Example

#define LEN 20
 
void  ParallelFor_Example()
{
    typedef struct {
        int32_t val[LEN];
        int32_t rangeLen;
    }Arg;
    // Operation of this function: Obtaining the absolute value of a segment in an array
    auto func = [] (int32_t i, void *arg) -> HmppResult {
        Arg *args = (Arg *)arg;
        int32_t st = i * args->rangeLen;
        int32_t ed = st + args->rangeLen;
        for (int32_t k = st; k < ed; ++k) {
            args->val[k] = abs(args->val[k]);
        }
        return HMPP_STS_NO_ERR;
    };

    Arg arg;
    arg.rangeLen = 5;
    for (int32_t i = 0; i < LEN; ++i) {
        arg.val[i] = -(i + 1);
    }

    HmppResult result = HMPP_ParallelFor(LEN / arg.rangeLen, (void*)&arg, func);

    for (int32_t i = 0; i < LEN; ++i) {
        printf("%d\n", arg.val[i]);
    }
}

Output:

Parent topic: Basic Functions