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| |
| /* |
| // Intel(R) Integrated Performance Primitives. Cryptography Primitives. |
| // Internal operations over GF(p) extension. |
| // |
| // Context: |
| // cpGFpGetOptimalWinSize() |
| // |
| */ |
| |
| #include "owncp.h" |
| #include "pcpbnumisc.h" |
| #include "pcpgfpxstuff.h" |
| #include "gsscramble.h" |
| |
| static int div_upper(int a, int d) |
| { return (a+d-1)/d; } |
| |
| static int getNumOperations(int bitsize, int w) |
| { |
| int n_overhead = (1<<w) -1; |
| int n_ops = div_upper(bitsize, w) + n_overhead; |
| return n_ops; |
| } |
| |
| int cpGFpGetOptimalWinSize(int bitsize) |
| { |
| int w_opt = 1; |
| int n_opt = getNumOperations(bitsize, w_opt); |
| int w_trial; |
| for(w_trial=w_opt+1; w_trial<=IPP_MAX_EXPONENT_NUM; w_trial++) { |
| int n_trial = getNumOperations(bitsize, w_trial); |
| if(n_trial>=n_opt) break; |
| w_opt = w_trial; |
| n_opt = n_trial; |
| } |
| return w_opt; |
| } |