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"""External function interface to BLAS libraries."""
import tvm
from tvm import te


def matmul(lhs, rhs, transa=False, transb=False, **kwargs):
    """Create an extern op that compute matrix mult of A and rhs with CrhsLAS
    This function serves as an example on how to call external libraries.

    Parameters
    ----------
    lhs: Tensor
        The left matrix operand
    rhs: Tensor
        The right matrix operand
    transa: bool
        Whether transpose lhs
    transb: bool
        Whether transpose rhs

    Returns
    -------
    C: Tensor
        The result tensor.
    """
    n = lhs.shape[1] if transa else lhs.shape[0]
    m = rhs.shape[0] if transb else rhs.shape[1]
    return te.extern(
        (n, m),
        [lhs, rhs],
        lambda ins, outs: tvm.tir.call_packed(
            "tvm.contrib.cblas.matmul", ins[0], ins[1], outs[0], transa, transb
        ),
        name="C",
        **kwargs,
    )


def batch_matmul(lhs, rhs, transa=False, transb=False, iterative=False, **kwargs):
    """Create an extern op that compute batched matrix mult of A and rhs with CBLAS
    This function serves as an example on how to call external libraries.

    Parameters
    ----------
    lhs: Tensor
        The left matrix operand
    rhs: Tensor
        The right matrix operand
    transa: bool
        Whether transpose lhs
    transb: bool
        Whether transpose rhs

    Returns
    -------
    C: Tensor
        The result tensor.
    """
    b = te.max(lhs.shape[0], rhs.shape[0])
    n = lhs.shape[2] if transa else lhs.shape[1]
    m = rhs.shape[1] if transb else rhs.shape[2]
    return te.extern(
        (b, n, m),
        [lhs, rhs],
        lambda ins, outs: tvm.tir.call_packed(
            "tvm.contrib.cblas.batch_matmul"
            if not iterative
            else "tvm.contrib.cblas.batch_matmul_iterative",
            ins[0],
            ins[1],
            outs[0],
            transa,
            transb,
        ),
        name="C",
        **kwargs,
    )
