Verilog Help

[Altera_Forum]

Hey Guyz! 

 I need some help with verilog coding. i got this code off opencore website that teaches us how to code a sd card controller.Below shows 2 of the verilog file.   A) spiMaster_defines.v `ifdef SIM_COMPILE `define SD_INIT_START_SEQ_LEN 8'h03 `define MAX_8_BIT 8'h08 `else `define SD_INIT_START_SEQ_LEN 8'ha0 `define MAX_8_BIT 8'hff `endif  B) initSD.v  `include "spiMaster_defines.v" `CLK_SEQ_CHK_FIN:  begin  next_txDataWen <= 1'b0;  if (loopCnt == `SD_INIT_START_SEQ_LEN)  begin  NextState_initSDSt <= `CLK_SEQ_WT_DATA_EMPTY;  end  else  begin  NextState_initSDSt <= `CLK_SEQ_SEND_FF;  end  end  My question is what is the value of `SD_INIT_START_SEQ_LEN ?? Also what is the verilog code in A trying to do? Hope someone can help me as i really need to understand this. Thank you. 

[Altera_Forum]

From the name, the first file appears to contain definitions for constants. The code you listed in 'A' defines two constants which are dependant on whether or not SIM_COMPILE is defined. If SIM_COMPILE is defined, SD_INIT_START_SEQ_LEN will be an 8 bit value of '3'. If SIM_COMPILE is not defined, SD_INIT_START_SEQ_LEN will be hex 'a0'.

[Altera_Forum]

Are you a C programmer? If so, the equivalent code for A) in C would be: 

# ifdef SIM_COMPILE # define SD_INIT_START_SEQ_LEN 0x03 # define MAX_8_BIT 0x08 # else # define SD_INIT_START_SEQ_LEN 0xa0 # define MAX_8_BIT 0xff # endif  So the value of SD_INIT_SEQ_LEN is either 3 or 160 depending on whether or not SIM_COMPILE is defined.  Most likely the designer defines the macro "SIM_COMPILE" when he wants to run a simulation because it takes less time.  Jake

[Altera_Forum]

Hey ereeves and jakobjones, 

 Thanks a lot for your advice and help. I understand now. Appreciate your advices and effort to help me.  Cheers!