用VHDL实现8位移位相加乘法器，从被乘数的最低位开始，若为1，则乘数左移后与上次的和相加；若为0，左移后以全0相加，直至被乘数的最高位。-VHDL 8-bit shift by adding the multiplier to achieve, starting from the lowest multiplicand, if 1, then left after the multiplier and add the last　if 0, left after adding all 0, until the highest bit multiplicand.