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SAMA5 PWM: Minor improvement to a loop

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This commit is contained in:
Gregory Nutt 2016-12-04 15:48:13 -06:00
parent 39c4ecbcd0
commit 6cff0a7012
1 changed files with 9 additions and 8 deletions
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17
arch/arm/src/sama5/sam_pwm.c
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@ -1,7 +1,7 @@
/****************************************************************************
* arch/arm/src/sama5/sam_pwm.c
*
* Copyright (C) 2013 Gregory Nutt. All rights reserved.
* Copyright (C) 2013, 2016 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
@ -1163,18 +1163,19 @@ static unsigned int pwm_clk_prescaler_log2(uint32_t mck, uint32_t fclk)
unscaled = mck / fclk;
prelog2 = 0;
while (unscaled >= 256 && prelog2 < 11)
/* Loop, incrementing the log2(prescaler) value. Exit with either:
*
* 1) unscaled < 256 and prelog2 <= 10, or with
* 2) unscaled >= 256 and prelog2 == 10
*/
while (unscaled >= 256 && prelog2 < 10)
{
unscaled >>= 1;
prelog2++;
}
DEBUGASSERT(prelog2 <= 10);
if (prelog2 > 10)
{
prelog2 = 10;
}
DEBUGASSERT(unscaled < 256);
return prelog2;
}