Program Listing for File MicroBitMemoryMap.cpp

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/*
The MIT License (MIT)

Copyright (c) 2016 British Broadcasting Corporation.
This software is provided by Lancaster University by arrangement with the BBC.

Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.
*/

#include "MicroBitConfig.h"
#include "MicroBitMemoryMap.h"
#include "MicroBitFlash.h"
#include "MicroBitSerial.h"

#include "sdk_config.h"
#include "app_util.h"
#include "crc32.h"

#define MAX_STRING_LENGTH 100

MicroBitMemoryMap::MicroBitMemoryMap()
{
      // Find Hashes
      findHashes();

}

int MicroBitMemoryMap::pushRegion(Region region)
{

    // Find next blank Region in map
    if(regionCount == NUMBER_OF_REGIONS){
        return MICROBIT_NO_RESOURCES;
    } else {
        // Add data
        memoryMapStore.memoryMap[regionCount].startAddress = region.startAddress;
        memoryMapStore.memoryMap[regionCount].endAddress   = region.endAddress;
        //memcpy(&memoryMapStore.memoryMap[regionCount].hash, &region.hash, 8);
        memoryMapStore.memoryMap[regionCount++].regionId     = region.regionId;
        return MICROBIT_OK;
    }
}

int MicroBitMemoryMap::updateRegion(Region region)
{
    // Find Region name in map
    int i = 0;
    while(memoryMapStore.memoryMap[i].regionId != region.regionId && i < NUMBER_OF_REGIONS) i++;

    if(i == NUMBER_OF_REGIONS){
        return MICROBIT_NO_RESOURCES;
    } else {
        // Add data
        memoryMapStore.memoryMap[i] = region;
        return MICROBIT_OK;
    }
}

/*
 * Function to fetch the hashes from a PXT generated build
 */
void MicroBitMemoryMap::findHashes()
{
    // Iterate through pages to find magic
    uint32_t add = FLASH_PROGRAM_END;
    uint32_t rem = add % PAGE_SIZE;
    if ( rem) add += PAGE_SIZE - rem;
    int step = PAGE_SIZE / sizeof( uint32_t);
    uint32_t *nxt = ( uint32_t *)MICROBIT_DEFAULT_SCRATCH_PAGE;


    for( uint32_t *magicAddress = (uint32_t *) add; magicAddress < nxt; magicAddress += step)
    {
        // Avoid storing magic in flash
        volatile uint32_t m1 = 0x6DC4718F;

        // Check for PXT magic
        if (   magicAddress[0] == ~m1
            && magicAddress[1] == 0x41A815C6
            && magicAddress[2] == 0xC96698C4
            && magicAddress[3] == 0x9751EE75) {

                // SD
                pushRegion(Region(REGION_SD, 0x00, MICROBIT_APP_REGION_START, 0x00));  // Soft Device

                // DAL
                pushRegion(Region(REGION_CODAL, MICROBIT_APP_REGION_START, FLASH_PROGRAM_END, 0x00)); // micro:bit Device Abstractation Layer

                // PXT
                // PXT will be on the start of the next page
                // padding to next page = PAGE_SIZE - (FLASH_PROGRAM_END % PAGE_SIZE);
                // Assume
                pushRegion(Region(REGION_MAKECODE,
                        FLASH_PROGRAM_END + (PAGE_SIZE - ( FLASH_PROGRAM_END % PAGE_SIZE)),
                        MICROBIT_APP_REGION_END,
                        0x00)); // micro:bit PXT


                // If the magic has been found use the hashes follow
                memcpy( memoryMapStore.memoryMap[1].hash, magicAddress + 4, 8);
                memcpy( memoryMapStore.memoryMap[2].hash, magicAddress + 6, 8);
                memoryMapStore.memoryMap[2].startAddress = (uint32_t)magicAddress;
                return;
        }

        // Check for Python magic
        if (   *(magicAddress - (sizeof(magicAddress))) == 0x597F30FE
            && *(magicAddress - (sizeof(magicAddress)/4))   == 0xC1B1D79D
           ) {
            // Found uPy Magic
            DMESG("FOUND UPY_MAGIC");
            uint8_t nRegions = (*(magicAddress - (sizeof(magicAddress)/2)));

            // Iterate through regions
            for(int i = 0; i < nRegions; i++) {
               processRecord(magicAddress - ((2 + i) * sizeof(magicAddress)));
            }

        }
    }
}


/*
 * Function to process record from uPy build
 * @return MICROBIT_OK success, MICROBIT_INVALID_PARAM if the region.id is too great
 */
int MicroBitMemoryMap::processRecord(uint32_t *address) {

    MicroPythonLayoutRecord record;
    memcpy(&record, address, sizeof(record));

    // Check for valid record id
    if(record.id > NUMBER_OF_REGIONS) return MICROBIT_INVALID_PARAMETER;

    uint32_t start = record.reg_page * MICROBIT_CODEPAGESIZE;
    uint32_t length = record.reg_len;

    DMESG("Python Layout Record. Record: %d Hash Type: %d Start: %x Length: %x Hash: %x %x"
                    , record.id
                    , record.ht
                    , start
                    , length
                    , record.hash_data[1]
                    , record.hash_data[0]);

    uint32_t hash[2];
    if(record.ht == HASH_TYPE_POINTER) {
        // Points to a string
        // Take string and generate 8 byte hash
        uint8_t * string = (uint8_t *) record.hash_data[0];
        int n   = 0;
        while(n < MAX_STRING_LENGTH && *(string + n) != '\0') {
            n++;
        }

        hash[0] = crc32_compute(string, n, NULL);
        hash[1] = 0;

        DMESG("Hash from version string: %x", hash[0]);
    } else {
        memcpy(&hash, record.hash_data, 8);
    }

    // Copy to memory map
    uint8_t index = record.id - 1;
    memcpy(memoryMapStore.memoryMap[index].hash, &hash, 8);
    memoryMapStore.memoryMap[index].regionId = record.id;
    memoryMapStore.memoryMap[index].startAddress = (uint32_t)start;
    memoryMapStore.memoryMap[index].endAddress = (uint32_t)(start + length);

    return MICROBIT_OK;
}