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Chapter 7 Code Optimization

AutoCode Reference 7-14 ni.com

All of the blocks can accept constants as inputs. If any input is available

during code generation time as a constant, the constant is used instead of a

symbol name (or variable name). This applies to blocks of both categories.

One limitation to this optimization is that a block cannot propagate

constants or even accept constants as inputs if its inputs or outputs contain

vectors. Such blocks with vector inputs or outputs use only the variable

name (or symbol name) and hence force the source blocks to generate code

for computing the value of output variables.

Example 7-9 shows code generated without constant propagation, and

Example 7-10 shows code generated with constant propagation.

Example 7-9 Code Generated without the Constant Propagation Option

void subsys_1(Y)

struct _Subsys_1_out *Y;

{

static RT_INTEGER iinfo[4];

/***** Local Block Outputs. *****/

RT_FLOAT const_1_1;

RT_FLOAT const_11_1;

RT_FLOAT const_2_1;

/******* Initialization. *******/

if (SUBSYS_PREINIT[1]) {

iinfo[0] = 0;

iinfo[1] = 1;

iinfo[2] = 1;

iinfo[3] = 1;

SUBSYS_PREINIT[1] = FALSE;

return;

}

/***** Output Update. *****/

/* ---------------------------- Algebraic Expression */

/* {const..1} */

const_1_1 = 5.0;

/* ---------------------------- Algebraic Expression */

/* {const..11} */

const_11_1 = 3.0;

/* ---------------------------- Sum of Vectors */

/* {const..2} */

const_2_1 = const_1_1 - const_11_1;

/* ---------------------------- Gain Block */

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National-instruments AutoCode NI MATRIX Manual do Utilizador Página 205