instructions

Do you know this Well I want create something like this screen. When I open for the first time the application I want open this screen and display a context.. How is possible? I don't know what search for this type of thing.. @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); ... if (isFirstTime()) { // What you do when the Application is Opened First time Goes here } ... } /*** * Checks that application runs first time and write flag at SharedPreferences * @return true if 1st time */ private boolean isFirstTime() { SharedPreferences preferences =

This question continues on my question here (on the advice of Mystical): C code loop performance Continuing on my question, when i use packed instructions instead of scalar instructions the code using intrinsics would look very similar: for(int i=0; i<size; i+=16) { y1 = _mm_load_ps(output[i]); … y4 = _mm_load_ps(output[i+12]); for(k=0; k<ksize; k++){ for(l=0; l<ksize; l++){ w = _mm_set_ps1(weight[i+k+l]); x1 = _mm_load_ps(input[i+k+l]); y1 = _mm_add_ps(y1,_mm_mul_ps(w,x1)); … x4 = _mm_load_ps(input[i+k+l+12]); y4 = _mm_add_ps(y4,_mm_mul_ps(w,x4)); } } _mm_store_ps(&output[i],y1); … _mm_store

I wanted to test if bitwise operations really are faster to execute than arithmetic operation. I thought they were. I wrote a small C program to test this hypothesis and to my surprise the addition takes less on average than bitwise AND operation. This is surprising to me and I cannot understand why this is happening. From what I know for addition the carry from the less significant bits should be carried to the next bits because the result depends on the carry too. It does not make sense to me that a logic operator is slower than addition. My cod is below: #include<stdio.h> #include<time.h>

If you look at documentation of operations like cmp , test , add , sub , and and , you will notice that operations that involve register EAX and its 16 and 8 bit variants as the first operand have a distinct opcode which is different from the "general case" version of these instructions. Is this separate opcode merely a way to save code space, is it at all more efficient than the general-case opcode, or is it just some relic of the past that isn't worth shaking off for compatibility reasons? This is primarily a relic of the past, but not exactly "obsolete" either. In the early days ( i.e. , on

I have a multiply-add kernel inside my application and I want to increase its performance. I use an Intel Core i7-960 (3.2 GHz clock) and have already manually implemented the kernel using SSE intrinsics as follows: for(int i=0; i<iterations; i+=4) { y1 = _mm_set_ss(output[i]); y2 = _mm_set_ss(output[i+1]); y3 = _mm_set_ss(output[i+2]); y4 = _mm_set_ss(output[i+3]); for(k=0; k<ksize; k++){ for(l=0; l<ksize; l++){ w = _mm_set_ss(weight[i+k+l]); x1 = _mm_set_ss(input[i+k+l]); y1 = _mm_add_ss(y1,_mm_mul_ss(w,x1)); … x4 = _mm_set_ss(input[i+k+l+3]); y4 = _mm_add_ss(y4,_mm_mul_ss(w,x4)); } } _mm

I like examples, so I wrote a bit of self-modifying code in c... #include <stdio.h> #include <sys/mman.h> // linux int main(void) { unsigned char *c = mmap(NULL, 7, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE| MAP_ANONYMOUS, -1, 0); // get executable memory c[0] = 0b11000111; // mov (x86_64), immediate mode, full-sized (32 bits) c[1] = 0b11000000; // to register rax (000) which holds the return value // according to linux x86_64 calling convention c[6] = 0b11000011; // return for (c[2] = 0; c[2] < 30; c[2]++) { // incr immediate data after every run // rest of immediate data (c[3:6]) are