小弟目前在编写一个CPLD小程序，用的是EPM7256AEti144,编译过程中遇到了问题，直接把代码和警告附上，请各位大侠多多指教，
Warning: Macrocell buffer inserted after node "pwm5~reg0"Warning: Macrocell buffer inserted after node "pwm18~reg0"Warning: Macrocell buffer inserted after node "pwm16~reg0"Warning: Macrocell buffer inserted after node "pwm17~reg0"Warning: Macrocell buffer inserted after node "pwm3~reg0"Warning: Macrocell buffer inserted after node "pwm4~reg0"Warning: Macrocell buffer inserted after node"pwm6~reg0"Warning: Macrocell bufferinserted after node "pwm7~reg0"Warning: Macrocell bufferinserted after node "pwm2~reg0" always@(posedge clk)beginif(~WR && ~XBUS)beginif(XA==1)begina1<=XD[0];endelse if(XA==2)begina2<=XD[0];endelse if(XA==3)begina3<=XD;endelse if(XA==4)begina4<=XD;endelse if(XA==5)begina5<=XD;endelse if(XA==6)begina6<=XD;endelse if(XA==7)begina7<=XD;endelse if(XA==15)begina15<=XD;endelse if(XA==21)begina21<=XD;endendend