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Re: [avr-chat] ensuring that _delay_us() gets a compile-time double cons
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From: |
Michael Hennebry |
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Subject: |
Re: [avr-chat] ensuring that _delay_us() gets a compile-time double constant |
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Date: |
Tue, 2 Dec 2014 18:36:05 -0600 (CST) |
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User-agent: |
Alpine 1.00 (DEB 882 2007-12-20) |
On Tue, 2 Dec 2014, Britton Kerin wrote:
1. Does _delay_us() need a double const, or is an int const guaranteed
to work? The avr libc manual just says "known const" in one place,
but the signature calls for a double.
_delay_us needs a double const.
It will get a double whether you give it a double or some other number.
That is what prototypes are for.
Prototypes are ordinary C.
In file included from one_wire_slave.c:8:0:
/home/bkerin/opt/avr/avr/include/util/delay.h: In function ‘ows_write_bit’:
/home/bkerin/opt/avr/avr/include/util/delay.h:163:28: error:
__builtin_avr_delay_cycles expects a compile time integer constant
__builtin_avr_delay_cycles(__ticks_dc);
My guess is that a variable or a non-constant
expression was passed to _delay_us.
--
Michael address@hidden
"SCSI is NOT magic. There are *fundamental technical
reasons* why it is necessary to sacrifice a young
goat to your SCSI chain now and then." -- John Woods