File system, unexpected write/read on disk output - c

Question

I've been working on this for 3 days, can't see the error, I need fresh eyes :)
I work on a online embedded class, and at this particular lab we need to implement a file system.
I have unexpected results as described in the code comments in the main function. (E=expected, R=result)
Write/read functions:
#define EDISK_ADDR_MIN 0x00020000 // Flash Bank1 minimum address
#define EDISK_ADDR_MAX 0x0003FFFF // Flash Bank1 maximum address
// Write an array of 32-bit data to flash starting at given address.
int Flash_FastWrite(uint32_t *source, uint32_t addr, uint16_t count)
{
uint32_t flashkey;
uint32_t volatile *FLASH_FWBn_R = (uint32_t volatile*)0x400FD100;
int writes = 0;
if(MassWriteAddrValid(addr))
{
DisableInterrupts(); // may be optional step
while(FLASH_FMC2_R&FLASH_FMC2_WRBUF){}; // wait for hardware idle
while((writes < 32) && (writes < count))
{
FLASH_FWBn_R[writes] = source[writes];
writes = writes + 1;
}
FLASH_FMA_R = addr;
if(FLASH_BOOTCFG_R&FLASH_BOOTCFG_KEY) // by default, the key is 0xA442
flashkey = FLASH_FMC_WRKEY;
else // otherwise, the key is 0x71D5
flashkey = FLASH_FMC_WRKEY2;
FLASH_FMC2_R = (flashkey|FLASH_FMC2_WRBUF); // start writing
while(FLASH_FMC2_R&FLASH_FMC2_WRBUF){};
EnableInterrupts();
}
return writes;
}
// Write 1 sector of 512 bytes of data to the disk, data comes from RAM
enum DRESULT eDisk_WriteSector(
const uint8_t *buff, // Pointer to the data to be written
uint8_t sector){ // sector number
uint32_t addr;
uint32_t *copybuff;
copybuff =(uint32_t*)(buff);//Flash_WriteArray needs uint32_t format
addr=EDISK_ADDR_MIN+(512*sector);// starting ROM address
if(addr>EDISK_ADDR_MAX) // return RES_PARERR if exceeds
return RES_PARERR;
Flash_WriteArray(copybuff, addr, 512);// write 512 bytes from RAM into ROM
// written by the instructor.
return RES_OK;
}
// Read 1 sector of 512 bytes from the disk, data goes to RAM
enum DRESULT eDisk_ReadSector(
uint8_t *buff, // Pointer to a RAM buffer into which to store
uint8_t sector){ // sector number to read from
uint16_t i;
uint8_t *diskpt;
diskpt=(uint8_t *)(EDISK_ADDR_MIN+512*sector); // starting ROM address
if(EDISK_ADDR_MIN+512*sector>EDISK_ADDR_MAX)
return RES_PARERR;
else
{
for ( i = 0; i < 512; i++ )// copy 512 bytes from ROM into RAM
buff[i] = *diskpt++;
return RES_OK;
}
}
enum DRESULT eDisk_Format(void){
// erase all flash from EDISK_ADDR_MIN to EDISK_ADDR_MAX
for(uint32_t i=EDISK_ADDR_MIN;i<=EDISK_ADDR_MAX;i++)
Flash_Erase(i);
return RES_OK;
}
uint8_t Buff[512];
int main(void)
{
eDisk_Init(0); // if(drive == 0){return RES_OK;}
eDisk_Format();
testbuildbuff("auf0");
eDisk_WriteSector(Buff,0);
testbuildbuff("Excelent"); // writes "Excelent" onto Buff
eDisk_WriteSector(Buff,1);
testbuildbuff("bus3");
eDisk_WriteSector(Buff,2);
testbuildbuff("bus4");
eDisk_WriteSector(Buff,3);
// E=expected. R=result
eDisk_ReadSector(Buff, 0); //E: Buff="auf0" R:Buff="auf0"
eDisk_ReadSector(Buff, 1); //E: Buff="Excelent" R: Buff is empty
eDisk_ReadSector(Buff, 2); //E: Buff="bus3" R: Buff is empty
eDisk_ReadSector(Buff, 3); //E: Buff="bus4" R: 4Buff is empty
return 0;
}
The Buff results after reed are unexpected. Why does it work for 0 but not the rest?
Even more strange is when I run this test:
testbuildbuff("auf0 buf1 buf2");
eDisk_WriteSector(Buff,2);
testbuildbuff("Excelent");
eDisk_WriteSector(Buff,1);
testbuildbuff("bus3");
eDisk_WriteSector(Buff,3);
testbuildbuff("bus4");
eDisk_WriteSector(Buff,4);
eDisk_ReadSector(Buff, 4); //Buff is empty
eDisk_ReadSector(Buff, 3); //Buff is empty
eDisk_ReadSector(Buff, 2); //Buff = "auf0 buf1 buf2"
eDisk_ReadSector(Buff, 1); //Buff = "Excelent"
What is happening?
PS: IDE Keil uVision v5.2, uC: TM4C123

Answer 1

The issue is at call of function Flash_WriteArray().
In Flash_WriteArray(), the last parameter should be the number of words (32-bit or 4 bytes) we want to write. To write 512 bytes, this parameter should be 128 (512/4).

Answer 2

Writing words and reading bytes may give you an endian issue if your cpu is big endian.