Comparison operation in SSE - c

Question

I am new to the SSE coding. I want to do write a SSE code for my algorithm. I want to convert below C code into SSE code.
for(int i=1;i<height;i++)
{
for(int j=1;j<width;j++)
{
int index = 0;
if(input[width*i + j]<=input[width*(i-1)+(j-1)])) index += 0x80;
if(input[width*i + j]<=input[width*(i-1)+(j )])) index += 0x40;
if(input[width*i + j]<=input[width*(i-1)+(j+1)])) index += 0x20;
if(input[width*i + j]<=input[width*(i )+(j-1)])) index += 0x10;
if(input[width*i + j]<=input[width*(i )+(j+1)])) index += 0x08;
if(input[width*i + j]<=input[width*(i+1)+(j-1)])) index += 0x04;
if(input[width*i + j]<=input[width*(i+1)+(j )])) index += 0x02;
if(input[width*i + j]<=input[width*(i+1)+(j+1)])) index ++;
output[width*(i-1)+(j-1)] = index;
}
}
Here is my SSE code:
unsigned char *dst_d = outputbuffer
float *CT_image_0 = inputbuffer;
float *CT_image_1 = CT_image_0 + width;
float *CT_image_2 = CT_image_1 + width;
for(int i=1;i<height;i++)
{
for(int j=1;j<width;j+=4)
{
__m128 CT_current_00 = _mm_loadu_ps((CT_image_0+j-1));
__m128 CT_current_10 = _mm_loadu_ps((CT_image_1+j-1));
__m128 CT_current_20 = _mm_loadu_ps((CT_image_2+j-1));
__m128 CT_current_01 = _mm_loadu_ps(((CT_image_0+1)+j-1));
__m128 CT_current_11 = _mm_loadu_ps(((CT_image_1+1)+j-1));
__m128 CT_current_21 = _mm_loadu_ps(((CT_image_2+1)+j-1));
__m128 CT_current_02 = _mm_loadu_ps(((CT_image_0+2)+j-1));
__m128 CT_current_12 = _mm_loadu_ps(((CT_image_1+2)+j-1));
__m128 CT_current_22 = _mm_loadu_ps(((CT_image_2+2)+j-1));
__m128 val = CT_current_11;
//Below I tried to write the SSE instruction but that was wrong :(
//--How I can do index + ...operation with this _mm_cmple_ss return value ????
__m128 sample6= _mm_cmple_ss(val,CT_current_00);
sample6 += _mm_cmple_ss(val,CT_current_01);
sample6 += _mm_cmple_ss(val,CT_current_02);
sample6 += _mm_cmple_ss(val,CT_current_10);
sample6 +=_mm_cmple_ss(val,CT_current_12);
sample6 +=_mm_cmple_ss(val,CT_current_20);
sample6 +=_mm_cmple_ss(val,CT_current_21);
sample6 +=_mm_cmple_ss(val,CT_current_22);
}
CT_image_0 +=width;
CT_image_1 +=width;
CT_image_2 +=width;
dst_d += (width-2);
}
I broke my head and trying (as a lay man)to use if condition ...Please give me some idea on this ???

Answer 1

The part that needs work is evidently this:
__m128 sample6= _mm_cmple_ss(val,CT_current_00);
sample6 += _mm_cmple_ss(val,CT_current_01);
sample6 += _mm_cmple_ss(val,CT_current_02);
sample6 += _mm_cmple_ss(val,CT_current_10);
sample6 +=_mm_cmple_ss(val,CT_current_12);
sample6 +=_mm_cmple_ss(val,CT_current_20);
sample6 +=_mm_cmple_ss(val,CT_current_21);
sample6 +=_mm_cmple_ss(val,CT_current_22);
You need to combine all the comparison results into a set of flags, e.g. like this:
__m128i out = _mm_setzero_si128(); // init output flags to all zeroes
__m128i test;
test = _mm_cmple_ss(val, CT_current_00); // compare
test = _mm_and_si128(test, _mm_set1_epi32(0x80)); // mask all but required flag
out = _mm_or_si128(out, test); // merge flags to output mask
test = _mm_cmple_ss(val, CT_current_01);
test = _mm_and_si128(test, _mm_set1_epi32(0x40));
out = _mm_or_si128(out, test);
// ... repeat for each offset and flag value
// ... then finally extract 4 bytes from `out`
// ... and store at output[width*(i-1)+(j-1)]

Answer 2

I do not know what SSE is code but more than likely you would want to run a/or some combination of combining CT_current variables into a string array and then concatenating them into a List with the before before mention (by your code), CT=** specification (where CT** is everything you put afterwards); in order to iterate back to the _m128 you print to, then as you know you can then double iterate as you've done.
Good Luck.