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POUsing C++ templates or macros for compile time function generation
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  1. POUsing C++ templates or macros for compile time function generation
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    copied!<p>I have a code that runs on an embedded system and it has to run really fast. I know C and macros, and this particular project is coded mostly in C but it also uses C++ templates [increasingly more]. There is an inline function:</p> <pre><code>inline my_t read_memory(uint32 addr) { #if (CURRENT_STATE &amp; OPTIMIZE_BITMAP) return readOptimized(addr); #else return MEMORY[addr]; #endif } </code></pre> <p>This function reads from memory in an optimized fashion or conventional fashion based on the current state and a bitmap that tells whether to use optimization in a specific state or not.</p> <pre><code>#define STATE_A 0x0001 #define STATE_B 0x0010 #define STATE_C 0x0100 #define STATE_D 0x1000 #define OPTIMIZE_BITMAP 0x1010 // optimize states d and b </code></pre> <p>and during the course of execution (ok, compilation), I tried to redefine CURRENT_STATE like so:</p> <pre><code>int main(){ #define CURRENT_STATE STATE_A do_a(); #undef CURRENT_STATE #define CURRENT_STATE STATE_B do_b(); .... } </code></pre> <p>All do_X() functions make read_memory() calls. I could not make this approach work. The value of current state is always STATE_A as I can see when I use #warning statements. This is not my question, although if you can help me with this I'll be double happy. So, my question is, is there a way to do this kind of thing using templates instead of macros?</p> <p>Some more info: I have to use an inline function because I cannot export MEMORY[] and this is a library function. I really prefer not to modify the function prototype (like read_memory()...) but it will do. Also, pardon my obscurity.</p> <p>many thanks,</p>
 

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