Incomprensible results from get_states without printf
laurent974
Posts: 77
in Propeller 1
Hello,
I have some strange behavior from the code below.
if i remove the printf, i have wrong values inside the variable d.
If someone can give me a clue?
I have some strange behavior from the code below.
if i remove the printf, i have wrong values inside the variable d.
If someone can give me a clue?
// --- define some value for reed grid ----
#define reed_start_Pin 8
#define reed_end_Pin 23
// colonnes en Pins pairs (start=8) et lignes sur Pins impairs
#define Columns 0x5555 //0b0101010101010101
#define Rows 0xAAAA //0b1010101010101010
#define Dir_RowOut_ColIn 0xAAAA // Output = 1 input = 0
// --- Pin Row Col ----
#define COL_A reed_start_Pin
#define ROW_1 (reed_start_Pin+1)
// ------ recup les colonnes ------
// récupere un bit sur 2 en partant de la droite
// ex si v = 0b11110010
// retour = 0b1100
int getcolpinval(unsigned int v)
{
unsigned int d,i;
// on passe de 2 en 2 vers la gauche (on shift v vers la droite)
for (d = 0; v; v >>= 2, i++) {
// on accumule le résultat dans d
d = d | (v&1) << i ;
}
return d;
}
// ------ Main Program ------
int main()
{
// Mettre les lignes en direction output et les colonnes en input
set_directions(reed_end_Pin,reed_start_Pin,Dir_RowOut_ColIn);
pause(500);
// mettre les lignes en High
set_outputs(reed_end_Pin,reed_start_Pin,RowsHigh);
pause(500);
unsigned int pinvalues = 0; // recupere les valeurs des pins
int rowpin = 0; // pins des lignes
int d = 0;
for(;;){
//pause(5000);
term_cmd(CRSRXY, TERM_X0, TERM_Y0);
for (int r = 4; r>=1; r--){
// Mettre la ligne a 0
rowpin=ROW_1+(r-1)*2;
set_output(rowpin,0);
pause(500);
// récupère les valeurs des colonnes
pinvalues = get_states(reed_end_Pin,reed_start_Pin);
//pause(1000);
// afficher
printf ("Row_%d: ",r); //// <===== here
d = getcolpinval(pinvalues);
printf("\td=%d\n",d); /// <== d is wrong if the printf above is commented
term_cmd(CRSRXY,TERM_X0,TERM_Y0 + 4-r+1);
// reinitialiser la ligne a High
set_output(rowpin,1);
// pause(500);
} // for row
} // for(;;)
}
Comments
Probabily the printf clears the stack locations used by that variable (local variables are allocated on the stack) so it works with printf but not without.
(How to do this depends on what compiler/IDE you are using...)
I usually use a makefile with everything inside because when code is too long, vim + makefile are a big win.
But this time i tried simpleIde and totally forgot to look at the compiler options.
Mike