bitsandbytes_mps/gemm/utils.h

// Copyright © 2024 Apple Inc.

#pragma once

#include <metal_stdlib>

METAL_FUNC ulong2 elem_to_loc_broadcast(
    uint elem,
    constant const int* shape,
    constant const int64_t* a_strides,
    constant const int64_t* b_strides,
    int ndim) {
  ulong loc_a{0};
  ulong loc_b{0};
  for (int i = ndim - 1; i >= 0 && elem > 0; --i) {
    int pos_in_dim = (elem % shape[i]);
    elem /= shape[i];
    loc_a += pos_in_dim * a_strides[i];
    loc_b += pos_in_dim * b_strides[i];
  }
  return ulong2(loc_a, loc_b);
}

METAL_FUNC ulong3 elem_to_loc_broadcast(
    uint elem,
    constant const int* shape,
    constant const int64_t* a_strides,
    constant const int64_t* b_strides,
    constant const int64_t* c_strides,
    int ndim) {
  ulong loc_a{0};
  ulong loc_b{0};
  ulong loc_c{0};
  for (int i = ndim - 1; i >= 0 && elem > 0; --i) {
    int pos_in_dim = (elem % shape[i]);
    elem /= shape[i];
    loc_a += pos_in_dim * a_strides[i];
    loc_b += pos_in_dim * b_strides[i];
    loc_c += pos_in_dim * c_strides[i];
  }
  return ulong3(loc_a, loc_b, loc_c);
}