static int ArrowIpcDecoderSwapEndian()

in extensions/nanoarrow_ipc/src/nanoarrow/nanoarrow_ipc_decoder.c [1309:1412]
95 lines of code
23 McCabe index (conditional complexity)

static int ArrowIpcDecoderSwapEndian(struct ArrowIpcBufferSource* src,
                                     struct ArrowBufferView* out_view,
                                     struct ArrowBuffer* dst, struct ArrowError* error) {
  // Some buffer data types don't need any endian swapping
  switch (src->data_type) {
    case NANOARROW_TYPE_BOOL:
    case NANOARROW_TYPE_INT8:
    case NANOARROW_TYPE_UINT8:
    case NANOARROW_TYPE_STRING:
    case NANOARROW_TYPE_BINARY:
      return NANOARROW_OK;
    default:
      break;
  }

  // Make sure dst is not a shared buffer that we can't modify
  struct ArrowBuffer tmp;
  ArrowBufferInit(&tmp);

  if (dst->allocator.private_data != NULL) {
    ArrowBufferMove(dst, &tmp);
    ArrowBufferInit(dst);
  }

  if (dst->size_bytes == 0) {
    NANOARROW_RETURN_NOT_OK(ArrowBufferReserve(dst, out_view->size_bytes));
    dst->size_bytes = out_view->size_bytes;
  }

  switch (src->data_type) {
    case NANOARROW_TYPE_DECIMAL128:
    case NANOARROW_TYPE_DECIMAL256: {
      const uint64_t* ptr_src = out_view->data.as_uint64;
      uint64_t* ptr_dst = (uint64_t*)dst->data;
      uint64_t words[4];
      int n_words = src->element_size_bits / 64;

      for (int64_t i = 0; i < (dst->size_bytes / n_words / 8); i++) {
        for (int j = 0; j < n_words; j++) {
          words[j] = bswap64(ptr_src[i * n_words + j]);
        }

        for (int j = 0; j < n_words; j++) {
          ptr_dst[i * n_words + j] = words[n_words - j - 1];
        }
      }
      break;
    }
    case NANOARROW_TYPE_INTERVAL_DAY_TIME: {
      uint32_t* ptr = (uint32_t*)dst->data;
      for (int64_t i = 0; i < (dst->size_bytes / 4); i++) {
        ptr[i] = bswap32(out_view->data.as_uint32[i]);
      }
      break;
    }
    case NANOARROW_TYPE_INTERVAL_MONTH_DAY_NANO: {
      const uint8_t* ptr_src = out_view->data.as_uint8;
      uint8_t* ptr_dst = dst->data;
      int item_size_bytes = 16;
      struct ArrowIpcIntervalMonthDayNano item;
      for (int64_t i = 0; i < (dst->size_bytes / item_size_bytes); i++) {
        memcpy(&item, ptr_src + i * item_size_bytes, item_size_bytes);
        item.months = bswap32(item.months);
        item.days = bswap32(item.days);
        item.ns = bswap64(item.ns);
        memcpy(ptr_dst + i * item_size_bytes, &item, item_size_bytes);
      }
      break;
    }
    default:
      switch (src->element_size_bits) {
        case 16: {
          uint16_t* ptr = (uint16_t*)dst->data;
          for (int64_t i = 0; i < (dst->size_bytes / 2); i++) {
            ptr[i] = bswap16(out_view->data.as_uint16[i]);
          }
          break;
        }
        case 32: {
          uint32_t* ptr = (uint32_t*)dst->data;
          for (int64_t i = 0; i < (dst->size_bytes / 4); i++) {
            ptr[i] = bswap32(out_view->data.as_uint32[i]);
          }
          break;
        }
        case 64: {
          uint64_t* ptr = (uint64_t*)dst->data;
          for (int64_t i = 0; i < (dst->size_bytes / 8); i++) {
            ptr[i] = bswap64(out_view->data.as_uint64[i]);
          }
          break;
        }
        default:
          ArrowErrorSet(error, "Endian swapping for element bitwidth %d is not supported",
                        (int)src->element_size_bits);
          return ENOTSUP;
      }
      break;
  }

  ArrowBufferReset(&tmp);
  out_view->data.data = dst->data;
  return NANOARROW_OK;
}