esp-idf/components/esp_rom/include/esp32s2/rom/usb/usb_persist.h

// Copyright 2019-2020 Espressif Systems (Shanghai) PTE LTD
//
// 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.

#pragma once

#include <stdint.h>

#ifdef __cplusplus
extern "C" {
#endif

// USB persistence flags.

//This bit indicates persistence has been enabled, that is, the USB initialization routines should not
//reset the USB device as the device still is initialized and the host detected it with the same cdcacm/dfu
//descriptor as the ROM uses; we can just re-initialize the software side and have at 'er.
#define USBDC_PERSIST_ENA (1<<31)

//This bit indicates to the ROM that we rebooted because of a request to go into DFU mode; the ROM should
//honour this request.
#define USBDC_BOOT_DFU (1<<30)


//This being non-0 indicates a memory location where a 'testament' is stored, aka a piece of text that should be output
//after a reboot. Can contain core dump info or something.
#define USBDC_TESTAMENT_LOC_MASK 0x7FFFF //bits 19-0; this is added to a base address of 0x3FF80000.

//The testament is a FIFO. The ROM will output all data between textstart and textend; if textend is lower than textstart it will
//output everything from textstart to memend, then memstart to textend.
typedef struct {
    char *memstart; //start of memory region
    char *memend;   //end of memory region
    char *textstart; //start of text to output
    char *textend;
} usbdc_testament_t;

#ifdef __cplusplus
}
#endif