What is the most efficient way to merge byte arrays in C? -

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say have 2 arrays of char, , each position either 1 or 0. 2 arrays calculated in different processes , sent master combined, each 1 writes range of array:

p1 : [0, 0, 0, 0, 1, 1, 0, 1]

p2 : [1, 0, 1, 1, 0, 0, 0, 0]

goal: [1, 0, 1, 1, 1, 1, 0, 1]

however, these large arrays. there super fast way of doing besides looping on 1 of them?

to clarify, should or'd.

assuming byte granularity enough, you'd want use memcpy copy them output array:

memcpy(goal, p2, 4); memcpy(goal + 4, p1 + 4, 4);

you can further optimize letting p1 , p2 contain own ranges, eg:

char p1[4] = { 1, 1, 0, 1 }; char p2[4] = { 1, 0, 1, 1 }; char goal[8]; memcpy(goal, p2, 4); memcpy(goal + 4, p1, 4);

note may want bit vector packing - pack 8 bits each char. save lot of memory large arrays, although complicates access.


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