File content as of revision 0:01f31e923fe2:

/**
 * @file    read_uid.c
 * @brief
 *
 * DAPLink Interface Firmware
 * Copyright (c) 2009-2016, ARM Limited, All Rights Reserved
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "read_uid.h"
#include "cortex_m.h"

#define IAP_LOCATION  *(volatile unsigned int *)(0x10400100)
static uint32_t command[5];
static uint32_t result[5];
typedef void (*IAP)(uint32_t[], uint32_t[]);

void read_unique_id(uint32_t *id)
{
#if defined(INTERNAL_FLASH)
    cortex_int_state_t local_state = cortex_int_get_and_disable();

    // readUID IAP call
    IAP iap_entry = (IAP)IAP_LOCATION;
    command[0] = 58;
    iap_entry(command, result);
    *id = result[1] ^ result[2] ^ result[3] ^ result[4];

    cortex_int_restore(local_state);
#else
    // IAP commands are only supported for parts with on-chip flash.
    (void)command;
    (void)result;
    *id = 0xdeadbeef;
#endif
}