spi interface stm-32

float gp22_read_n_bytes(void *bus_type, uint8_t n_bytes, uint8_t read_opcode,
                   uint8_t read_addr, uint8_t fractional_bits)
{
  uint32_t    Result_read = 0;
  float       Result = 0;
  uint8_t     read_opcode_addr = read_opcode | read_addr;

  //.............. Result = n Byte = n x 8 bits......................
  if (bus_type==SPI1 | bus_type==SPI2) 
  {
       // Deactivating Reset SPIx
       if (bus_type==SPI1) GPIO_WriteBit(GPIOA, GPIO_Pin_4, Bit_RESET);
       if (bus_type==SPI2) GPIO_WriteBit(GPIOB, GPIO_Pin_12, Bit_RESET);
      
       SPI_I2S_SendData(bus_type, read_opcode_addr);  // READ OPCODE + Address
       
       while (SPI_I2S_GetFlagStatus(bus_type, SPI_I2S_FLAG_TXE)==RESET) {};
  Simple_delay_750ns((void*)10); // important delay (16) at SPI freq.=750kHz
       
       //Compulsory reads to DR and SR to clear OVR,
       //so that next incoming data is saved
       SPI_I2S_ReceiveData(bus_type);                     // To clear OVR
       SPI_I2S_GetFlagStatus(bus_type, SPI_I2S_FLAG_TXE); // To clear OVR

         //Reading byte1
         SPI_I2S_SendData(bus_type, 0x00FF);  // DUMMY WRITE
         // Wait until RX buffer is not empty, then read the received data
         while (SPI_I2S_GetFlagStatus(bus_type, SPI_I2S_FLAG_RXNE)==0) {}
         Result_read = SPI_I2S_ReceiveData(bus_type); //  Read

       for (int n = 1; n < n_bytes; n++)
       {       
         //Reading byte2 .. byte.n
         SPI_I2S_SendData(bus_type, 0x00FF);  // DUMMY WRITE
         // Wait until RX buffer is not empty, then read the received data
         while (SPI_I2S_GetFlagStatus(bus_type, SPI_I2S_FLAG_RXNE)==0) {}

         Result_read = Result_read<<8;
         Result_read |= SPI_I2S_ReceiveData(bus_type); //  Read
       }

       // Reset to device SPIx
       if (bus_type==SPI1) GPIO_WriteBit(GPIOA, GPIO_Pin_4, Bit_SET);
       if (bus_type==SPI2) GPIO_WriteBit(GPIOB, GPIO_Pin_12, Bit_SET);
  }
  
  Result = Result_read / pow(2, fractional_bits);

  return Result;
}