FSMC SRAM问题

scony1

  #if 1
  p.FSMC_AddressSetupTime = 0;
  p.FSMC_AddressHoldTime = 0;
  p.FSMC_DataSetupTime = 2;
  p.FSMC_BusTurnAroundDuration = 0;
  p.FSMC_CLKDivision = 0;
  p.FSMC_DataLatency = 0;
  #elif 0
  p.FSMC_AddressSetupTime = 15;
  p.FSMC_AddressHoldTime = 15;
  p.FSMC_DataSetupTime = 15;
  p.FSMC_BusTurnAroundDuration = 15;
  p.FSMC_CLKDivision = 8;
  p.FSMC_DataLatency = 15;
  #endif

这段代码的含义是什么？ 代码将配置那一段？

flyleaf

第一段，这是预编译宏