On Thu, 21 Jul 2016 22:01:40 +1000 Erik Christiansen <dva...@internode.on.net> wrote:
> I wouldn't go to the trouble of a C program, but do it with a lot less
> lines of awk, but that's just taste.
That's not going to help.
E.g. on the tiny841,
#define LFUSE_DEFAULT (FUSE_SUT_CKSEL0 & FUSE_SUT_CKSEL2 & \
FUSE_SUT_CKSEL3 & FUSE_SUT_CKSEL4 & FUSE_CKDIV8)
#define HFUSE_DEFAULT (FUSE_SPIEN)
#define EFUSE_DEFAULT (0xFF)
That doesn't help directly, as you need to know the values of those
individual FUSE_* constants. OK, so they are:
#define FUSE_SUT_CKSEL0 (unsigned char)~_BV(0)
#define FUSE_SUT_CKSEL1 (unsigned char)~_BV(1)
#define FUSE_SUT_CKSEL2 (unsigned char)~_BV(2)
#define FUSE_SUT_CKSEL3 (unsigned char)~_BV(3)
#define FUSE_SUT_CKSEL4 (unsigned char)~_BV(4)
...
Alright. Um we're going to need _BV(). Except that isn't found in this
file. I'll have to follow the #include chain.
So now I need to understand how #include works. And #define.
And *then* I'm going to have to understand the ~ and & operators, along
with the << operator of _BV's actual definition.
Or; I could just generate/compile/run the following C program:
#include <avr/io.h>
printf("lfuse=%02x:hfuse=%02x:efuse=%02x\n",
LFUSE_DEFAULt, HFUSE_DEFAULT, EFUSE_DEFAULT);
and out comes the answer directly without my having to do any other
work.
Big spoiler: I already wrote lots of code for doing exactly this kind
of "please get me values out of system .h files":
https://metacpan.org/pod/ExtUtils::H2PM
So in practice I'll just be running that.
--
Paul "LeoNerd" Evans
leon...@leonerd.org.uk | https://metacpan.org/author/PEVANS
http://www.leonerd.org.uk/ | https://www.tindie.com/stores/leonerd/
pgpdOj4zkdtj1.pgp
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