Function std::rocm_concat

int rocm_concat(
    struct RocmBuf a,
    unsigned long na,
    struct RocmBuf c,
    unsigned long nc,
    struct RocmBuf out,
    unsigned long batch,
)

out[b] = (a[b], c[b]) for 'batch' rows of na and nc elements, one launch (the channel concat of NCHW tensors: na = aChannels * height * width).