randomm.nc

来自「tinyos密钥管理组件 用在tinyos仿真里的」· NC 代码 · 共 45 行

module RandomM 
{
  provides interface Random;
}
implementation
{
  uint16_t shiftReg;
  uint16_t initSeed;
  uint16_t mask;

  /* Initialize the seed from the ID of the node */
  async command result_t Random.init() {
    dbg(DBG_BOOT, "RANDOM_LFSR initialized.\n");
    atomic {
      shiftReg = 119 * 119 * (1 + 1);
      initSeed = shiftReg;
      mask = 137 * 29 * (1 + 1);
    }
    return SUCCESS;
  }

  /* Return the next 16 bit random number */
  async command uint16_t Random.rand() {
    bool endbit;
    uint16_t tmpShiftReg;
    atomic {
      tmpShiftReg = shiftReg;
      endbit = ((tmpShiftReg & 0x8000) != 0);
      tmpShiftReg <<= 1;
      if (endbit) 
	tmpShiftReg ^= 0x100b;
      tmpShiftReg++;
      shiftReg = tmpShiftReg;
      tmpShiftReg = tmpShiftReg ^ mask;
    }
    return tmpShiftReg;
  }
  
//  uint16_t TOSH_rand() __attribute__((C)) {
//    return call Random.rand();
//  }
}