#include <sysinit.h>
#include <string.h>

#include "basic/basic.h"

#include "lcd/print.h"

#include "usb/usbmsc.h"

#include "filesystem/ff.h"
#include "filesystem/select.h"

#include "basic/xxtea.h"

const uint32_t signature_key[4] = {0x123456,0,0,0x234567};
const uint32_t decode_key[4] = {0x123456,0,0,0x234567};
//const uint32_t decode_key[4] = {0,0,0,0};

extern void * sram_top;

/**************************************************************************/

uint8_t execute_file (const char * fname, uint8_t checksignature, uint8_t decode){
    FRESULT res;
    FIL file;
    UINT readbytes;
    void (*dst)(void);

    /* XXX: why doesn't this work? sram_top contains garbage?
    dst=(void (*)(void)) (sram_top); 
    lcdPrint("T:"); lcdPrintIntHex(dst); lcdNl();
    */
    dst=(void (*)(void)) 0x1000160C;

    res=f_open(&file, fname, FA_OPEN_EXISTING|FA_READ);

    //lcdPrint("open: ");
    //lcdPrintln(f_get_rc_string(res));
    //lcdRefresh();
    if(res){
        return -1;
    };
    
    res = f_read(&file, (char *)dst, RAMCODE, &readbytes);
    //lcdPrint("read: ");
    //lcdPrintln(f_get_rc_string(res));
    //lcdRefresh();
    if(res){
        return -1;
    };
    if( decode || checksignature )
        //only accept files with fixed length
        //if( readbytes != 2048 )
        if( readbytes & 0x3 ){
            lcdPrint("readbytes&3");
            lcdRefresh();
            while(1);
            return -1;
        }
    if( checksignature ){
        uint32_t mac[4];
        uint32_t *data = (uint32_t*)dst;
        uint32_t len = readbytes/4;
        xxtea_cbcmac(mac, (uint32_t*)dst, len-4, signature_key);
        if( data[len-4] != mac[0] || data[len-3] != mac[1]
            || data[len-2] != mac[2] || data[len-1] != mac[3] ){
            lcdClear();
            lcdPrint("mac wrong");lcdNl();
            lcdPrintIntHex(mac[0]); lcdNl();
            lcdPrintIntHex(mac[1]); lcdNl();
            lcdPrintIntHex(mac[2]); lcdNl();
            lcdPrintIntHex(mac[3]); lcdNl();
            lcdRefresh();
            while(1); 
            return -1;
        }
        //lcdPrint("macok");
        //lcdRefresh();
        //while(1);
    }

    if( decode ){
        uint32_t *data = (uint32_t*)dst;
        uint32_t len = readbytes/4;
        xxtea_decode_words(data, len-4, decode_key);
    }
    //lcdPrintInt(readbytes);
    //lcdPrintln(" bytes");
    //lcdRefresh();

    dst=(void (*)(void)) ((uint32_t)(dst) | 1); // Enable Thumb mode!
    dst();
    return 0;

};

/**************************************************************************/

void executeSelect(char *ext){
    char filename[15];
    filename[0]='0';
    filename[1]=':';
    filename[2]=0;

    if( selectFile(filename+2,ext) == 0)
        execute_file(filename,0,0);
};