DLL

#if defined(_WIN32)
  #define dllexport __declspec(dllexport)
#else
  #define dllexport
#endif

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <time.h>

void bsx_loadBSX2(uint8_t count, uint8_t size);

struct BSX_BASE {
  uint8_t r2188, r2189, r218a, r218b;
  uint8_t r218c, r218d, r218e, r218f;
  uint8_t r2190, r2191, r2192, r2193;
  uint8_t r2194, r2195, r2196, r2197;
  uint8_t r2198, r2199, r219a, r219b;
  uint8_t r219c, r219d, r219e, r219f;

  bool r218b_access, r218c_access;
  uint16_t r218b_count, r218c_count, r2191_count, r2192_count;
  uint8_t r218c_sec_count;
  uint8_t BSX1[20];
  uint8_t BSX2[440];

  uint8_t r2192_hour, r2192_min, r2192_sec;

} bsx_base;

struct BSX_FUNC {
    void loadBSX2(unsigned char count) {
        FILE *BSXF = fopen("BSX2.bin","rb");
            if(BSXF != NULL) {
                fpos_t position = count*512;
                fsetpos(BSXF, &position);
                if(fgets((char*)bsx_base.BSX2, 440, BSXF) != NULL) bsx_base.r218c_access=true;
                else bsx_base.r218c_access=false;
                fclose(BSXF);
            }
    }
} bsx_func;

extern "C" {
  void link_power();
  void link_reset();
  unsigned link_run();
  uint8_t link_read(unsigned addr);
  void link_write(unsigned addr, uint8_t data);
}

dllexport void link_power() {
  link_reset();
}

dllexport void link_reset() {
  printf("Start.");
  FILE *BSX = fopen("BSX1.bin","rb");
  if(BSX != NULL) {
    fpos_t position = 0;
    fsetpos(BSX, &position);
    if(fgets((char*)bsx_base.BSX1, 20, BSX) != NULL) bsx_base.r218b_access=true;
    else bsx_base.r218b_access=false;
    fclose(BSX);
  }
  bsx_func.loadBSX2(0);

  bsx_base.r2188, bsx_base.r2189, bsx_base.r218a, bsx_base.r218b = 0;
  bsx_base.r218c, bsx_base.r218d, bsx_base.r218e, bsx_base.r218f = 0;
  bsx_base.r2190, bsx_base.r2191, bsx_base.r2192, bsx_base.r2193 = 0;
  bsx_base.r2194, bsx_base.r2195, bsx_base.r2196, bsx_base.r2197 = 0;
  bsx_base.r2198, bsx_base.r2199, bsx_base.r219a, bsx_base.r219b = 0;
  bsx_base.r219c, bsx_base.r219d, bsx_base.r219e, bsx_base.r219f = 0;

  bsx_base.r218b_count, bsx_base.r218c_count, bsx_base.r2191_count, bsx_base.r2192_count = 0;
  bsx_base.r218c_sec_count = 0;
}

dllexport unsigned link_run() {
  return 1u;
}

dllexport uint8_t link_read(unsigned addr) {
  printf("* Read  %.6x\n", addr);
  addr &= 0xffff;

  switch(addr) {
    case 0x2188: return bsx_base.r2188;
    case 0x2189: return bsx_base.r2189;
    case 0x218A: return 0x14;
    case 0x218B: {
        if(bsx_base.r218b!=0) {
            bsx_base.r218b_count++;
            if(bsx_base.r218b_count>20) bsx_base.r218b_count=1;
            return bsx_base.BSX1[bsx_base.r218b_count-1];
        }
    }
    case 0x218C: {
        if(bsx_base.r218c!=0) {
            bsx_base.r218c_count++;
            if(bsx_base.r218c_count>440) bsx_base.r218c_count=1;
            return bsx_base.BSX2[bsx_base.r218c_count-1];
        }
    }
    case 0x218D: return 0x10;
    case 0x218E: return bsx_base.r218e;
    case 0x218F: return bsx_base.r218f;
    case 0x2190: return bsx_base.r2190;
    case 0x2191: return bsx_base.r2191;
    case 0x2192: {
        if(bsx_base.r2192 != 0) {
            time_t rawtime;
            time(&rawtime);
            tm *t = localtime(&rawtime);
            bsx_base.r2192_hour = t->tm_hour;
            bsx_base.r2192_min = t->tm_min;
            bsx_base.r2192_sec = t->tm_sec;

            bsx_base.r2192_count++;
            if(bsx_base.r2192_count>=18) bsx_base.r2192_count = 0;
            switch(bsx_base.r2192_count - 1) {
                case 0: return 0;
                case 1: return 0;
                case 2: return 0;
                case 3: return 0;
                case 4: return 0;
                case 5: return 1;
                case 6: return 1;
                case 7: return 0;
                case 8: return 0;
                case 9: return 0;
                case 10: return bsx_base.r2192_sec; //Seconds
                case 11: return bsx_base.r2192_min; //Minutes
                case 12: return bsx_base.r2192_hour; //Hours
                case 13: return 0;
                case 14: return 0;
                case 15: return 0;
                case 16: return 0;
                case 17: return 0;
            }
        }
    }
    case 0x2193: return bsx_base.r2193;
    case 0x2194: return bsx_base.r2194;
    case 0x2195: return bsx_base.r2195;
    case 0x2196: return bsx_base.r2196;
    case 0x2197: return bsx_base.r2197;
    case 0x2198: return bsx_base.r2198;
    case 0x2199: return bsx_base.r2199;
  }
  return 0x00;
}

dllexport void link_write(unsigned addr, uint8_t data) {
  printf("* Write %.6x = %.2x\n", addr, data);
  addr &= 0xffff;

  switch(addr) {
    case 0x2188: bsx_base.r2188=data;
    case 0x2189: bsx_base.r2189=data&0x3f;
    //case 0x218A: bsx_base.r218a=data;
    case 0x218B: bsx_base.r218b=data&1;
    case 0x218C: {
    bsx_base.r218c=data&1;
    bsx_base.r218c_count++;
    bsx_func.loadBSX2(bsx_base.r218c_count-1);
    }
    //case 0x218D: bsx_base.r218d=data;
    case 0x218E: bsx_base.r218e=data;
    case 0x218F: bsx_base.r218f=data&0x3f;
    //case 0x2190: bsx_base.r2190=data;
    case 0x2191: bsx_base.r2191=data&1;
    case 0x2192: bsx_base.r2192=data&1;
    //case 0x2193: bsx_base.r2193=data;
    case 0x2194: bsx_base.r2194=data&0x0f;
    //case 0x2195: bsx_base.r2195=data;
    //case 0x2196: bsx_base.r2196=data;
    case 0x2197: bsx_base.r2197=data;
    //case 0x2198: bsx_base.r2198=data;
    case 0x2199: bsx_base.r2199=data&0x42;
  }
}