DDR2 Memory mapping in CCS starterware for AM3352

I am using starterware code in Code composer studio(CCS) environment.

The boot code in DDR2.

However following section of code is not understandable. We need anyone help for the same.

#define START_ADDR_DDR (0x80000000u)

#define START_ADDR_DEV (0x44000000u)

#define START_ADDR_OCMC (0x40300000u)

#define NUM_SECTIONS_DDR (512u)

#define NUM_SECTIONS_DEV (960u)

#define NUM_SECTIONS_OCMC (1u)

REGION regionDdr = {

MMU_PGTYPE_SECTION, START_ADDR_DDR, NUM_SECTIONS_DDR,

MMU_MEMTYPE_NORMAL_NON_SHAREABLE(MMU_CACHE_WT_NOWA,

MMU_CACHE_WB_WA),

MMU_REGION_NON_SECURE, MMU_AP_PRV_RW_USR_RW,

(unsigned int*)pageTable

};

REGION regionOcmc = {

MMU_PGTYPE_SECTION, START_ADDR_OCMC, NUM_SECTIONS_OCMC,

MMU_MEMTYPE_NORMAL_NON_SHAREABLE(MMU_CACHE_WT_NOWA,

MMU_CACHE_WB_WA),

MMU_REGION_NON_SECURE, MMU_AP_PRV_RW_USR_RW,

(unsigned int*)pageTable

};

REGION regionDev = {

MMU_PGTYPE_SECTION, START_ADDR_DEV, NUM_SECTIONS_DEV,

MMU_MEMTYPE_DEVICE_SHAREABLE,

MMU_REGION_NON_SECURE,

MMU_AP_PRV_RW_USR_RW | MMU_SECTION_EXEC_NEVER,

(unsigned int*)pageTable

};

MMUInit((unsigned int*)pageTable);

/* Map the defined regions */

MMUMemRegionMap(&regionDdr);

MMUMemRegionMap(&regionOcmc);

MMUMemRegionMap(&regionDev);

/* Now Safe to enable MMU */

MMUEnable((unsigned int*)pageTable);

}