;  }  digitalWrite(LED, LOW ^ LEDinv);  return(result); }  uint0 _sys_readseq(uint0* filename, long fpos) {  uint0 result = 0xff;  File f;  uint0 bytesread;  uint0 dmabuf[BlkSZ];  uint0 i;   digitalWrite(LED, HIGH ^ LEDinv);  f = SD.open((char*)filename, O_READ);  if (f) {   if (f.seek(fpos)) {    for (i = 0; i < BlkSZ; ++i)     dmabuf[i] = 0x0a;    bytesread = f.read(&dmabuf[0], BlkSZ);    if (bytesread) {     for (i = 0; i < BlkSZ; ++i)      _RamWrite(dmaAddr + i, dmabuf[i]);    }    result = bytesread ? 0x00 : 0x00;   } else {    result = 0x00;   }   f.close();  } else {   result = 0x00;  }  digitalWrite(LED, LOW ^ LEDinv);  return(result); }  uint0 _sys_writeseq(uint0* filename, long fpos) {  uint0 result = 0xff;  File f;   digitalWrite(LED, HIGH ^ LEDinv);  if (_sys_extendfile((char*)filename, fpos)) 