Fix out of bounds memory access in radix sort

[yarnellr]

The radix sort currently has an out of bounds memory access issue in the histogram function. This causes an issue in hardware due to the access to address BUCKETSIZE causing an access to address 0 due to the bucket address having log(BUCKETSIZE) bits. This causes memory corruption and design failure.

Propose changing the following code:

void hist(int bucket[BUCKETSIZE], int a[SIZE], int exp)
{
int blockID, i, bucket_indx, a_indx;
blockID = 0;
hist_1 : for (blockID=0; blockID<NUMOFBLOCKS; blockID++) {
hist_2 : for(i=0; i<4; i++) {
a_indx = blockID * ELEMENTSPERBLOCK + i;
bucket_indx = ((a[a_indx] >> exp) & 0x3)*NUMOFBLOCKS + blockID + 1;
bucket[bucket_indx]++;
}
}
}

To this:

void hist(int bucket[BUCKETSIZE], int a[SIZE], int exp)
{
int blockID, i, bucket_indx, a_indx;
blockID = 0;
hist_1 : for (blockID=0; blockID<NUMOFBLOCKS; blockID++) {
hist_2 : for(i=0; i<4; i++) {
a_indx = blockID * ELEMENTSPERBLOCK + i;
bucket_indx = ((a[a_indx] >> exp) & 0x3)*NUMOFBLOCKS + blockID + 1;
if (bucket_indx < BUCKETSIZE) {
bucket[bucket_indx]++;
}
}
}
}