一种使用VHDL程序的硬件外演化模型

针对硬件演化中内演化过分依赖专业硬件平台的问题，提出了一种基于VHDL程序的硬件外演化模型VHDLEM。根据VHDL程序语句的不同，VHDLEM分为条件行为模型CAM和遗传程序模型GPM。CAM模型使用条件判断语句模式对电路真值表进行编码演化，得到的个体转换为条件判断形式的VHDL语句，对于输入较少的电路，CAM的演化速度快；GPM模型根据VHDL的逻辑运算语句，使用遗传程序设计的方法, 演化出对应真值表的电路逻辑表达式，转换为对应的VHDL程序，对于输入较多的电路，GPM模型得到的VHDL程序较CAM更加简洁，可读性更强。

An External Hardware Evolution Model Using VHDL Code

Aiming at the shortcoming of internal evolvable hardware dependent on professional hardware, this paper proposes a hardware evolving model, VHDLEM, based on the generative mechanism of VHDL. According to the different style of expression in VHDL, VHDLEM is divided two models, the condition action model, CAM, and the genetic programming model, GPM. In CAM, the truth table is encoded as binary sequence by using condition-judgment structure. If the target circuit has fewer inputs, the evolutionary of CAM can attain a higher rate. GPM is based on the logical expression in VHDL, in which the target circuit logical expression is converted to VHDL by means of genetic programming for the case that the target circuit has many inputs, the readability of VHDL evolved by GMP is better than that of CAM.