2009-10-06 13:11:04 __delay unit of measurement
Pawel Pastuszak (CANADA)
Message: 80904
In the following function __delay what is the measurement unit or was is the lowest values example nanoseconds?
What i looking is to do an delay in nano seconds i need to calculate 250ns of a delay.
static inline void __delay(unsigned long loops)
{
if (ANOMALY_05000312) {
/* Interrupted loads to loop registers -> bad */
unsigned long tmp;
__asm__ __volatile__(
"[--SP] = LC0;"
"[--SP] = LT0;"
"[--SP] = LB0;"
"LSETUP (1f,1f) LC0 = %1;"
"1: NOP;"
/* We take advantage of the fact that LC0 is 0 at
* the end of the loop. Otherwise we'd need some
* NOPs after the CLI here.
*/
"CLI %0;"
"LB0 = [SP++];"
"LT0 = [SP++];"
"LC0 = [SP++];"
"STI %0;"
: "=d" (tmp)
: "a" (loops)
);
} else
__asm__ __volatile__ (
"LSETUP(1f, 1f) LC0 = %0;"
"1: NOP;"
:
: "a" (loops)
: "LT0", "LB0", "LC0"
);
}
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2009-10-06 13:22:35 Re: __delay unit of measurement
Mike Frysinger (UNITED STATES)
Message: 80907
there is no "scale". __delay() does what it's told -- it loops for the specified number of nops. read the udelay() function if you want to figure out how to scale it.